/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>

#include "sd-bus.h"
#include "sd-messages.h"

#include "af-list.h"
#include "alloc-util.h"
#include "blockdev-util.h"
#include "bpf-devices.h"
#include "bpf-firewall.h"
#include "bpf-foreign.h"
#include "bpf-program.h"
#include "bpf-restrict-ifaces.h"
#include "bpf-socket-bind.h"
#include "btrfs-util.h"
#include "bus-error.h"
#include "bus-locator.h"
#include "cgroup.h"
#include "cgroup-setup.h"
#include "cgroup-util.h"
#include "devnum-util.h"
#include "errno-util.h"
#include "extract-word.h"
#include "fd-util.h"
#include "fdset.h"
#include "fileio.h"
#include "in-addr-prefix-util.h"
#include "inotify-util.h"
#include "ip-protocol-list.h"
#include "limits-util.h"
#include "manager.h"
#include "netlink-internal.h"
#include "nulstr-util.h"
#include "parse-util.h"
#include "path-util.h"
#include "percent-util.h"
#include "pidref.h"
#include "process-util.h"
#include "procfs-util.h"
#include "serialize.h"
#include "set.h"
#include "special.h"
#include "stdio-util.h"
#include "string-table.h"
#include "string-util.h"
#include "strv.h"
#include "virt.h"

#if BPF_FRAMEWORK
#include "bpf-dlopen.h"
#include "bpf-link.h"
#include "bpf-restrict-fs.h"
#include "bpf/restrict-fs/restrict-fs-skel.h"
#endif

#define CGROUP_CPU_QUOTA_DEFAULT_PERIOD_USEC (100 * USEC_PER_MSEC)

/* Returns the log level to use when cgroup attribute writes fail. When an attribute is missing or we have access
 * problems we downgrade to LOG_DEBUG. This is supposed to be nice to container managers and kernels which want to mask
 * out specific attributes from us. */
#define LOG_LEVEL_CGROUP_WRITE(r) ((ABS(r) == ENOENT || ERRNO_IS_FS_WRITE_REFUSED(r)) ? LOG_DEBUG : LOG_WARNING)

static void unit_remove_from_cgroup_empty_queue(Unit *u);

uint64_t cgroup_tasks_max_resolve(const CGroupTasksMax *tasks_max) {
        if (tasks_max->scale == 0)
                return tasks_max->value;

        return system_tasks_max_scale(tasks_max->value, tasks_max->scale);
}

bool manager_owns_host_root_cgroup(Manager *m) {
        assert(m);

        /* Returns true if we are managing the root cgroup. Note that it isn't sufficient to just check whether the
         * group root path equals "/" since that will also be the case if CLONE_NEWCGROUP is in the mix. Since there's
         * appears to be no nice way to detect whether we are in a CLONE_NEWCGROUP namespace we instead just check if
         * we run in any kind of container virtualization. */

        if (MANAGER_IS_USER(m))
                return false;

        if (detect_container() > 0)
                return false;

        return empty_or_root(m->cgroup_root);
}

bool unit_has_host_root_cgroup(const Unit *u) {
        assert(u);
        assert(u->manager);

        /* Returns whether this unit manages the root cgroup. This will return true if this unit is the root slice and
         * the manager manages the root cgroup. */

        if (!manager_owns_host_root_cgroup(u->manager))
                return false;

        return unit_has_name(u, SPECIAL_ROOT_SLICE);
}

bool unit_has_startup_cgroup_constraints(Unit *u) {
        assert(u);

        /* Returns true if this unit has any directives which apply during
         * startup/shutdown phases. */

        CGroupContext *c;

        c = unit_get_cgroup_context(u);
        if (!c)
                return false;

        return c->startup_io_weight != CGROUP_WEIGHT_INVALID ||
               c->startup_cpuset_cpus.set ||
               c->startup_cpuset_mems.set ||
               c->startup_memory_high_set ||
               c->startup_memory_max_set ||
               c->startup_memory_swap_max_set||
               c->startup_memory_zswap_max_set ||
               c->startup_memory_low_set;
}

static int set_attribute_and_warn(Unit *u, const char *attribute, const char *value) {
        int r;

        assert(u);
        assert(attribute);
        assert(value);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return -EOWNERDEAD;

        r = cg_set_attribute(SYSTEMD_CGROUP_CONTROLLER, crt->cgroup_path, attribute, value);
        if (r < 0)
                log_unit_full_errno(u, LOG_LEVEL_CGROUP_WRITE(r), r, "Failed to set '%s' attribute on '%s' to '%.*s': %m",
                                    attribute, empty_to_root(crt->cgroup_path), (int) strcspn(value, NEWLINE), value);

        return r;
}

void cgroup_context_init(CGroupContext *c) {
        assert(c);

        /* Initialize everything to the kernel defaults. When initializing a bool member to 'true', make
         * sure to serialize in execute-serialize.c using serialize_bool() instead of
         * serialize_bool_elide(), as sd-executor will initialize here to 'true', but serialize_bool_elide()
         * skips serialization if the value is 'false' (as that's the common default), so if the value at
         * runtime is zero it would be lost after deserialization. Same when initializing uint64_t and other
         * values, update/add a conditional serialization check. This is to minimize the amount of
         * serialized data that is sent to the sd-executor, so that there is less work to do on the default
         * cases. */

        *c = (CGroupContext) {
                .cpu_weight = CGROUP_WEIGHT_INVALID,
                .startup_cpu_weight = CGROUP_WEIGHT_INVALID,
                .cpu_quota_per_sec_usec = USEC_INFINITY,
                .cpu_quota_period_usec = USEC_INFINITY,

                .memory_high = CGROUP_LIMIT_MAX,
                .startup_memory_high = CGROUP_LIMIT_MAX,
                .memory_max = CGROUP_LIMIT_MAX,
                .startup_memory_max = CGROUP_LIMIT_MAX,
                .memory_swap_max = CGROUP_LIMIT_MAX,
                .startup_memory_swap_max = CGROUP_LIMIT_MAX,
                .memory_zswap_max = CGROUP_LIMIT_MAX,
                .startup_memory_zswap_max = CGROUP_LIMIT_MAX,

                .memory_zswap_writeback = true,

                .io_weight = CGROUP_WEIGHT_INVALID,
                .startup_io_weight = CGROUP_WEIGHT_INVALID,

                .tasks_max = CGROUP_TASKS_MAX_UNSET,

                .moom_swap = MANAGED_OOM_AUTO,
                .moom_mem_pressure = MANAGED_OOM_AUTO,
                .moom_preference = MANAGED_OOM_PREFERENCE_NONE,
                /* The default duration value in oomd.conf will be used when
                 * moom_mem_pressure_duration_usec is set to infinity. */
                .moom_mem_pressure_duration_usec = USEC_INFINITY,

                .memory_pressure_watch = _CGROUP_PRESSURE_WATCH_INVALID,
                .memory_pressure_threshold_usec = USEC_INFINITY,
        };
}

void cgroup_context_free_device_allow(CGroupContext *c, CGroupDeviceAllow *a) {
        assert(c);
        assert(a);

        LIST_REMOVE(device_allow, c->device_allow, a);
        free(a->path);
        free(a);
}

void cgroup_context_free_io_device_weight(CGroupContext *c, CGroupIODeviceWeight *w) {
        assert(c);
        assert(w);

        LIST_REMOVE(device_weights, c->io_device_weights, w);
        free(w->path);
        free(w);
}

void cgroup_context_free_io_device_latency(CGroupContext *c, CGroupIODeviceLatency *l) {
        assert(c);
        assert(l);

        LIST_REMOVE(device_latencies, c->io_device_latencies, l);
        free(l->path);
        free(l);
}

void cgroup_context_free_io_device_limit(CGroupContext *c, CGroupIODeviceLimit *l) {
        assert(c);
        assert(l);

        LIST_REMOVE(device_limits, c->io_device_limits, l);
        free(l->path);
        free(l);
}

void cgroup_context_remove_bpf_foreign_program(CGroupContext *c, CGroupBPFForeignProgram *p) {
        assert(c);
        assert(p);

        LIST_REMOVE(programs, c->bpf_foreign_programs, p);
        free(p->bpffs_path);
        free(p);
}

void cgroup_context_remove_socket_bind(CGroupSocketBindItem **head) {
        assert(head);

        LIST_CLEAR(socket_bind_items, *head, free);
}

void cgroup_context_done(CGroupContext *c) {
        assert(c);

        while (c->io_device_weights)
                cgroup_context_free_io_device_weight(c, c->io_device_weights);

        while (c->io_device_latencies)
                cgroup_context_free_io_device_latency(c, c->io_device_latencies);

        while (c->io_device_limits)
                cgroup_context_free_io_device_limit(c, c->io_device_limits);

        while (c->device_allow)
                cgroup_context_free_device_allow(c, c->device_allow);

        cgroup_context_remove_socket_bind(&c->socket_bind_allow);
        cgroup_context_remove_socket_bind(&c->socket_bind_deny);

        c->ip_address_allow = set_free(c->ip_address_allow);
        c->ip_address_deny = set_free(c->ip_address_deny);

        c->ip_filters_ingress = strv_free(c->ip_filters_ingress);
        c->ip_filters_egress = strv_free(c->ip_filters_egress);

        while (c->bpf_foreign_programs)
                cgroup_context_remove_bpf_foreign_program(c, c->bpf_foreign_programs);

        c->restrict_network_interfaces = set_free(c->restrict_network_interfaces);

        cpu_set_done(&c->cpuset_cpus);
        cpu_set_done(&c->startup_cpuset_cpus);
        cpu_set_done(&c->cpuset_mems);
        cpu_set_done(&c->startup_cpuset_mems);

        c->delegate_subgroup = mfree(c->delegate_subgroup);

        nft_set_context_clear(&c->nft_set_context);
}

static int unit_get_kernel_memory_limit(Unit *u, const char *file, uint64_t *ret) {
        assert(u);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return -EOWNERDEAD;

        return cg_get_attribute_as_uint64("memory", crt->cgroup_path, file, ret);
}

static int unit_compare_memory_limit(Unit *u, const char *property_name, uint64_t *ret_unit_value, uint64_t *ret_kernel_value) {
        CGroupContext *c;
        CGroupMask m;
        const char *file;
        uint64_t unit_value;
        int r;

        /* Compare kernel memcg configuration against our internal systemd state.
         *
         * Returns:
         *
         * <0: On error.
         *  0: If the kernel memory setting doesn't match our configuration.
         * >0: If the kernel memory setting matches our configuration.
         *
         * The following values are only guaranteed to be populated on return >=0:
         *
         * - ret_unit_value will contain our internal expected value for the unit, page-aligned.
         * - ret_kernel_value will contain the actual value presented by the kernel. */

        assert(u);

        /* The root slice doesn't have any controller files, so we can't compare anything. */
        if (unit_has_name(u, SPECIAL_ROOT_SLICE))
                return -ENODATA;

        /* It's possible to have MemoryFoo set without systemd wanting to have the memory controller enabled,
         * for example, in the case of DisableControllers= or cgroup_disable on the kernel command line. To
         * avoid specious errors in these scenarios, check that we even expect the memory controller to be
         * enabled at all. */
        m = unit_get_target_mask(u);
        if (!FLAGS_SET(m, CGROUP_MASK_MEMORY))
                return -ENODATA;

        assert_se(c = unit_get_cgroup_context(u));

        bool startup = u->manager && IN_SET(manager_state(u->manager), MANAGER_STARTING, MANAGER_INITIALIZING, MANAGER_STOPPING);

        if (streq(property_name, "MemoryLow")) {
                unit_value = unit_get_ancestor_memory_low(u);
                file = "memory.low";
        } else if (startup && streq(property_name, "StartupMemoryLow")) {
                unit_value = unit_get_ancestor_startup_memory_low(u);
                file = "memory.low";
        } else if (streq(property_name, "MemoryMin")) {
                unit_value = unit_get_ancestor_memory_min(u);
                file = "memory.min";
        } else if (streq(property_name, "MemoryHigh")) {
                unit_value = c->memory_high;
                file = "memory.high";
        } else if (startup && streq(property_name, "StartupMemoryHigh")) {
                unit_value = c->startup_memory_high;
                file = "memory.high";
        } else if (streq(property_name, "MemoryMax")) {
                unit_value = c->memory_max;
                file = "memory.max";
        } else if (startup && streq(property_name, "StartupMemoryMax")) {
                unit_value = c->startup_memory_max;
                file = "memory.max";
        } else if (streq(property_name, "MemorySwapMax")) {
                unit_value = c->memory_swap_max;
                file = "memory.swap.max";
        } else if (startup && streq(property_name, "StartupMemorySwapMax")) {
                unit_value = c->startup_memory_swap_max;
                file = "memory.swap.max";
        } else if (streq(property_name, "MemoryZSwapMax")) {
                unit_value = c->memory_zswap_max;
                file = "memory.zswap.max";
        } else if (startup && streq(property_name, "StartupMemoryZSwapMax")) {
                unit_value = c->startup_memory_zswap_max;
                file = "memory.zswap.max";
        } else
                return -EINVAL;

        r = unit_get_kernel_memory_limit(u, file, ret_kernel_value);
        if (r < 0)
                return log_unit_debug_errno(u, r, "Failed to parse %s: %m", file);

        /* It's intended (soon) in a future kernel to not expose cgroup memory limits rounded to page
         * boundaries, but instead separate the user-exposed limit, which is whatever userspace told us, from
         * our internal page-counting. To support those future kernels, just check the value itself first
         * without any page-alignment. */
        if (*ret_kernel_value == unit_value) {
                *ret_unit_value = unit_value;
                return 1;
        }

        /* The current kernel behaviour, by comparison, is that even if you write a particular number of
         * bytes into a cgroup memory file, it always returns that number page-aligned down (since the kernel
         * internally stores cgroup limits in pages). As such, so long as it aligns properly, everything is
         * cricket. */
        if (unit_value != CGROUP_LIMIT_MAX)
                unit_value = PAGE_ALIGN_DOWN(unit_value);

        *ret_unit_value = unit_value;

        return *ret_kernel_value == *ret_unit_value;
}

#define FORMAT_CGROUP_DIFF_MAX 128

static char *format_cgroup_memory_limit_comparison(Unit *u, const char *property_name, char *buf, size_t l) {
        uint64_t kval, sval;
        int r;

        assert(u);
        assert(property_name);
        assert(buf);
        assert(l > 0);

        r = unit_compare_memory_limit(u, property_name, &sval, &kval);

        /* memory.swap.max is special in that it relies on CONFIG_MEMCG_SWAP (and the default swapaccount=1).
         * In the absence of reliably being able to detect whether memcg swap support is available or not,
         * only complain if the error is not ENOENT. This is similarly the case for memory.zswap.max relying
         * on CONFIG_ZSWAP. */
        if (r > 0 || IN_SET(r, -ENODATA, -EOWNERDEAD) ||
            (r == -ENOENT && STR_IN_SET(property_name,
                                        "MemorySwapMax",
                                        "StartupMemorySwapMax",
                                        "MemoryZSwapMax",
                                        "StartupMemoryZSwapMax")))
                buf[0] = 0;
        else if (r < 0) {
                errno = -r;
                (void) snprintf(buf, l, " (error getting kernel value: %m)");
        } else
                (void) snprintf(buf, l, " (different value in kernel: %" PRIu64 ")", kval);

        return buf;
}

const char* cgroup_device_permissions_to_string(CGroupDevicePermissions p) {
        static const char *table[_CGROUP_DEVICE_PERMISSIONS_MAX] = {
                /* Lets simply define a table with every possible combination. As long as those are just 8 we
                 * can get away with it. If this ever grows to more we need to revisit this logic though. */
                [0]                                                          = "",
                [CGROUP_DEVICE_READ]                                         = "r",
                [CGROUP_DEVICE_WRITE]                                        = "w",
                [CGROUP_DEVICE_MKNOD]                                        = "m",
                [CGROUP_DEVICE_READ|CGROUP_DEVICE_WRITE]                     = "rw",
                [CGROUP_DEVICE_READ|CGROUP_DEVICE_MKNOD]                     = "rm",
                [CGROUP_DEVICE_WRITE|CGROUP_DEVICE_MKNOD]                    = "wm",
                [CGROUP_DEVICE_READ|CGROUP_DEVICE_WRITE|CGROUP_DEVICE_MKNOD] = "rwm",
        };

        if (p < 0 || p >= _CGROUP_DEVICE_PERMISSIONS_MAX)
                return NULL;

        return table[p];
}

CGroupDevicePermissions cgroup_device_permissions_from_string(const char *s) {
        CGroupDevicePermissions p = 0;

        if (!s)
                return _CGROUP_DEVICE_PERMISSIONS_INVALID;

        for (const char *c = s; *c; c++) {
                if (*c == 'r')
                        p |= CGROUP_DEVICE_READ;
                else if (*c == 'w')
                        p |= CGROUP_DEVICE_WRITE;
                else if (*c == 'm')
                        p |= CGROUP_DEVICE_MKNOD;
                else
                        return _CGROUP_DEVICE_PERMISSIONS_INVALID;
        }

        return p;
}

void cgroup_context_dump(Unit *u, FILE* f, const char *prefix) {
        _cleanup_free_ char *disable_controllers_str = NULL, *delegate_controllers_str = NULL, *cpuset_cpus = NULL, *cpuset_mems = NULL, *startup_cpuset_cpus = NULL, *startup_cpuset_mems = NULL;
        CGroupContext *c;
        struct in_addr_prefix *iaai;
        char cda[FORMAT_CGROUP_DIFF_MAX], cdb[FORMAT_CGROUP_DIFF_MAX], cdc[FORMAT_CGROUP_DIFF_MAX], cdd[FORMAT_CGROUP_DIFF_MAX],
                cde[FORMAT_CGROUP_DIFF_MAX], cdf[FORMAT_CGROUP_DIFF_MAX], cdg[FORMAT_CGROUP_DIFF_MAX], cdh[FORMAT_CGROUP_DIFF_MAX],
                cdi[FORMAT_CGROUP_DIFF_MAX], cdj[FORMAT_CGROUP_DIFF_MAX], cdk[FORMAT_CGROUP_DIFF_MAX];

        assert(u);
        assert(f);

        assert_se(c = unit_get_cgroup_context(u));

        prefix = strempty(prefix);

        (void) cg_mask_to_string(c->disable_controllers, &disable_controllers_str);
        (void) cg_mask_to_string(c->delegate_controllers, &delegate_controllers_str);

        /* "Delegate=" means "yes, but no controllers". Show this as "(none)". */
        const char *delegate_str = delegate_controllers_str ?: c->delegate ? "(none)" : "no";

        cpuset_cpus = cpu_set_to_range_string(&c->cpuset_cpus);
        startup_cpuset_cpus = cpu_set_to_range_string(&c->startup_cpuset_cpus);
        cpuset_mems = cpu_set_to_range_string(&c->cpuset_mems);
        startup_cpuset_mems = cpu_set_to_range_string(&c->startup_cpuset_mems);

        fprintf(f,
                "%sIOAccounting: %s\n"
                "%sMemoryAccounting: %s\n"
                "%sTasksAccounting: %s\n"
                "%sIPAccounting: %s\n"
                "%sCPUWeight: %" PRIu64 "\n"
                "%sStartupCPUWeight: %" PRIu64 "\n"
                "%sCPUQuotaPerSecSec: %s\n"
                "%sCPUQuotaPeriodSec: %s\n"
                "%sAllowedCPUs: %s\n"
                "%sStartupAllowedCPUs: %s\n"
                "%sAllowedMemoryNodes: %s\n"
                "%sStartupAllowedMemoryNodes: %s\n"
                "%sIOWeight: %" PRIu64 "\n"
                "%sStartupIOWeight: %" PRIu64 "\n"
                "%sDefaultMemoryMin: %" PRIu64 "\n"
                "%sDefaultMemoryLow: %" PRIu64 "\n"
                "%sMemoryMin: %" PRIu64 "%s\n"
                "%sMemoryLow: %" PRIu64 "%s\n"
                "%sStartupMemoryLow: %" PRIu64 "%s\n"
                "%sMemoryHigh: %" PRIu64 "%s\n"
                "%sStartupMemoryHigh: %" PRIu64 "%s\n"
                "%sMemoryMax: %" PRIu64 "%s\n"
                "%sStartupMemoryMax: %" PRIu64 "%s\n"
                "%sMemorySwapMax: %" PRIu64 "%s\n"
                "%sStartupMemorySwapMax: %" PRIu64 "%s\n"
                "%sMemoryZSwapMax: %" PRIu64 "%s\n"
                "%sStartupMemoryZSwapMax: %" PRIu64 "%s\n"
                "%sMemoryZSwapWriteback: %s\n"
                "%sTasksMax: %" PRIu64 "\n"
                "%sDevicePolicy: %s\n"
                "%sDisableControllers: %s\n"
                "%sDelegate: %s\n"
                "%sManagedOOMSwap: %s\n"
                "%sManagedOOMMemoryPressure: %s\n"
                "%sManagedOOMMemoryPressureLimit: " PERMYRIAD_AS_PERCENT_FORMAT_STR "\n"
                "%sManagedOOMPreference: %s\n"
                "%sMemoryPressureWatch: %s\n"
                "%sCoredumpReceive: %s\n",
                prefix, yes_no(c->io_accounting),
                prefix, yes_no(c->memory_accounting),
                prefix, yes_no(c->tasks_accounting),
                prefix, yes_no(c->ip_accounting),
                prefix, c->cpu_weight,
                prefix, c->startup_cpu_weight,
                prefix, FORMAT_TIMESPAN(c->cpu_quota_per_sec_usec, 1),
                prefix, FORMAT_TIMESPAN(c->cpu_quota_period_usec, 1),
                prefix, strempty(cpuset_cpus),
                prefix, strempty(startup_cpuset_cpus),
                prefix, strempty(cpuset_mems),
                prefix, strempty(startup_cpuset_mems),
                prefix, c->io_weight,
                prefix, c->startup_io_weight,
                prefix, c->default_memory_min,
                prefix, c->default_memory_low,
                prefix, c->memory_min, format_cgroup_memory_limit_comparison(u, "MemoryMin", cda, sizeof(cda)),
                prefix, c->memory_low, format_cgroup_memory_limit_comparison(u, "MemoryLow", cdb, sizeof(cdb)),
                prefix, c->startup_memory_low, format_cgroup_memory_limit_comparison(u, "StartupMemoryLow", cdc, sizeof(cdc)),
                prefix, c->memory_high, format_cgroup_memory_limit_comparison(u, "MemoryHigh", cdd, sizeof(cdd)),
                prefix, c->startup_memory_high, format_cgroup_memory_limit_comparison(u, "StartupMemoryHigh", cde, sizeof(cde)),
                prefix, c->memory_max, format_cgroup_memory_limit_comparison(u, "MemoryMax", cdf, sizeof(cdf)),
                prefix, c->startup_memory_max, format_cgroup_memory_limit_comparison(u, "StartupMemoryMax", cdg, sizeof(cdg)),
                prefix, c->memory_swap_max, format_cgroup_memory_limit_comparison(u, "MemorySwapMax", cdh, sizeof(cdh)),
                prefix, c->startup_memory_swap_max, format_cgroup_memory_limit_comparison(u, "StartupMemorySwapMax", cdi, sizeof(cdi)),
                prefix, c->memory_zswap_max, format_cgroup_memory_limit_comparison(u, "MemoryZSwapMax", cdj, sizeof(cdj)),
                prefix, c->startup_memory_zswap_max, format_cgroup_memory_limit_comparison(u, "StartupMemoryZSwapMax", cdk, sizeof(cdk)),
                prefix, yes_no(c->memory_zswap_writeback),
                prefix, cgroup_tasks_max_resolve(&c->tasks_max),
                prefix, cgroup_device_policy_to_string(c->device_policy),
                prefix, strempty(disable_controllers_str),
                prefix, delegate_str,
                prefix, managed_oom_mode_to_string(c->moom_swap),
                prefix, managed_oom_mode_to_string(c->moom_mem_pressure),
                prefix, PERMYRIAD_AS_PERCENT_FORMAT_VAL(UINT32_SCALE_TO_PERMYRIAD(c->moom_mem_pressure_limit)),
                prefix, managed_oom_preference_to_string(c->moom_preference),
                prefix, cgroup_pressure_watch_to_string(c->memory_pressure_watch),
                prefix, yes_no(c->coredump_receive));

        if (c->delegate_subgroup)
                fprintf(f, "%sDelegateSubgroup: %s\n",
                        prefix, c->delegate_subgroup);

        if (c->memory_pressure_threshold_usec != USEC_INFINITY)
                fprintf(f, "%sMemoryPressureThresholdSec: %s\n",
                        prefix, FORMAT_TIMESPAN(c->memory_pressure_threshold_usec, 1));

        if (c->moom_mem_pressure_duration_usec != USEC_INFINITY)
                fprintf(f, "%sManagedOOMMemoryPressureDurationSec: %s\n",
                        prefix, FORMAT_TIMESPAN(c->moom_mem_pressure_duration_usec, 1));

        LIST_FOREACH(device_allow, a, c->device_allow)
                /* strna() below should be redundant, for avoiding -Werror=format-overflow= error. See #30223. */
                fprintf(f,
                        "%sDeviceAllow: %s %s\n",
                        prefix,
                        a->path,
                        strna(cgroup_device_permissions_to_string(a->permissions)));

        LIST_FOREACH(device_weights, iw, c->io_device_weights)
                fprintf(f,
                        "%sIODeviceWeight: %s %" PRIu64 "\n",
                        prefix,
                        iw->path,
                        iw->weight);

        LIST_FOREACH(device_latencies, l, c->io_device_latencies)
                fprintf(f,
                        "%sIODeviceLatencyTargetSec: %s %s\n",
                        prefix,
                        l->path,
                        FORMAT_TIMESPAN(l->target_usec, 1));

        LIST_FOREACH(device_limits, il, c->io_device_limits)
                for (CGroupIOLimitType type = 0; type < _CGROUP_IO_LIMIT_TYPE_MAX; type++)
                        if (il->limits[type] != cgroup_io_limit_defaults[type])
                                fprintf(f,
                                        "%s%s: %s %s\n",
                                        prefix,
                                        cgroup_io_limit_type_to_string(type),
                                        il->path,
                                        FORMAT_BYTES(il->limits[type]));

        SET_FOREACH(iaai, c->ip_address_allow)
                fprintf(f, "%sIPAddressAllow: %s\n", prefix,
                        IN_ADDR_PREFIX_TO_STRING(iaai->family, &iaai->address, iaai->prefixlen));
        SET_FOREACH(iaai, c->ip_address_deny)
                fprintf(f, "%sIPAddressDeny: %s\n", prefix,
                        IN_ADDR_PREFIX_TO_STRING(iaai->family, &iaai->address, iaai->prefixlen));

        STRV_FOREACH(path, c->ip_filters_ingress)
                fprintf(f, "%sIPIngressFilterPath: %s\n", prefix, *path);
        STRV_FOREACH(path, c->ip_filters_egress)
                fprintf(f, "%sIPEgressFilterPath: %s\n", prefix, *path);

        LIST_FOREACH(programs, p, c->bpf_foreign_programs)
                fprintf(f, "%sBPFProgram: %s:%s",
                        prefix, bpf_cgroup_attach_type_to_string(p->attach_type), p->bpffs_path);

        if (c->socket_bind_allow) {
                fprintf(f, "%sSocketBindAllow: ", prefix);
                cgroup_context_dump_socket_bind_items(c->socket_bind_allow, f);
                fputc('\n', f);
        }

        if (c->socket_bind_deny) {
                fprintf(f, "%sSocketBindDeny: ", prefix);
                cgroup_context_dump_socket_bind_items(c->socket_bind_deny, f);
                fputc('\n', f);
        }

        if (c->restrict_network_interfaces) {
                char *iface;
                SET_FOREACH(iface, c->restrict_network_interfaces)
                        fprintf(f, "%sRestrictNetworkInterfaces: %s\n", prefix, iface);
        }

        FOREACH_ARRAY(nft_set, c->nft_set_context.sets, c->nft_set_context.n_sets)
                fprintf(f, "%sNFTSet: %s:%s:%s:%s\n", prefix, nft_set_source_to_string(nft_set->source),
                        nfproto_to_string(nft_set->nfproto), nft_set->table, nft_set->set);
}

void cgroup_context_dump_socket_bind_item(const CGroupSocketBindItem *item, FILE *f) {
        const char *family, *colon1, *protocol = "", *colon2 = "";

        family = strempty(af_to_ipv4_ipv6(item->address_family));
        colon1 = isempty(family) ? "" : ":";

        if (item->ip_protocol != 0) {
                protocol = ip_protocol_to_tcp_udp(item->ip_protocol);
                colon2 = ":";
        }

        if (item->nr_ports == 0)
                fprintf(f, "%s%s%s%sany", family, colon1, protocol, colon2);
        else if (item->nr_ports == 1)
                fprintf(f, "%s%s%s%s%" PRIu16, family, colon1, protocol, colon2, item->port_min);
        else {
                uint16_t port_max = item->port_min + item->nr_ports - 1;
                fprintf(f, "%s%s%s%s%" PRIu16 "-%" PRIu16, family, colon1, protocol, colon2,
                        item->port_min, port_max);
        }
}

void cgroup_context_dump_socket_bind_items(const CGroupSocketBindItem *items, FILE *f) {
        bool first = true;

        LIST_FOREACH(socket_bind_items, bi, items) {
                if (first)
                        first = false;
                else
                        fputc(' ', f);

                cgroup_context_dump_socket_bind_item(bi, f);
        }
}

int cgroup_context_add_device_allow(CGroupContext *c, const char *dev, CGroupDevicePermissions p) {
        _cleanup_free_ CGroupDeviceAllow *a = NULL;
        _cleanup_free_ char *d = NULL;

        assert(c);
        assert(dev);
        assert(p >= 0 && p < _CGROUP_DEVICE_PERMISSIONS_MAX);

        if (p == 0)
                p = _CGROUP_DEVICE_PERMISSIONS_ALL;

        a = new(CGroupDeviceAllow, 1);
        if (!a)
                return -ENOMEM;

        d = strdup(dev);
        if (!d)
                return -ENOMEM;

        *a = (CGroupDeviceAllow) {
                .path = TAKE_PTR(d),
                .permissions = p,
        };

        LIST_PREPEND(device_allow, c->device_allow, a);
        TAKE_PTR(a);

        return 0;
}

int cgroup_context_add_or_update_device_allow(CGroupContext *c, const char *dev, CGroupDevicePermissions p) {
        assert(c);
        assert(dev);
        assert(p >= 0 && p < _CGROUP_DEVICE_PERMISSIONS_MAX);

        if (p == 0)
                p = _CGROUP_DEVICE_PERMISSIONS_ALL;

        LIST_FOREACH(device_allow, b, c->device_allow)
                if (path_equal(b->path, dev)) {
                        b->permissions = p;
                        return 0;
                }

        return cgroup_context_add_device_allow(c, dev, p);
}

int cgroup_context_add_bpf_foreign_program(CGroupContext *c, uint32_t attach_type, const char *bpffs_path) {
        CGroupBPFForeignProgram *p;
        _cleanup_free_ char *d = NULL;

        assert(c);
        assert(bpffs_path);

        if (!path_is_normalized(bpffs_path) || !path_is_absolute(bpffs_path))
                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Path is not normalized.");

        d = strdup(bpffs_path);
        if (!d)
                return log_oom();

        p = new(CGroupBPFForeignProgram, 1);
        if (!p)
                return log_oom();

        *p = (CGroupBPFForeignProgram) {
                .attach_type = attach_type,
                .bpffs_path = TAKE_PTR(d),
        };

        LIST_PREPEND(programs, c->bpf_foreign_programs, TAKE_PTR(p));

        return 0;
}

#define UNIT_DEFINE_ANCESTOR_MEMORY_LOOKUP(entry)                       \
        uint64_t unit_get_ancestor_##entry(Unit *u) {                   \
                CGroupContext *c;                                       \
                                                                        \
                /* 1. Is entry set in this unit? If so, use that.       \
                 * 2. Is the default for this entry set in any          \
                 *    ancestor? If so, use that.                        \
                 * 3. Otherwise, return CGROUP_LIMIT_MIN. */            \
                                                                        \
                assert(u);                                              \
                                                                        \
                c = unit_get_cgroup_context(u);                         \
                if (c && c->entry##_set)                                \
                        return c->entry;                                \
                                                                        \
                while ((u = UNIT_GET_SLICE(u))) {                       \
                        c = unit_get_cgroup_context(u);                 \
                        if (c && c->default_##entry##_set)              \
                                return c->default_##entry;              \
                }                                                       \
                                                                        \
                /* We've reached the root, but nobody had default for   \
                 * this entry set, so set it to the kernel default. */  \
                return CGROUP_LIMIT_MIN;                                \
}

UNIT_DEFINE_ANCESTOR_MEMORY_LOOKUP(memory_low);
UNIT_DEFINE_ANCESTOR_MEMORY_LOOKUP(startup_memory_low);
UNIT_DEFINE_ANCESTOR_MEMORY_LOOKUP(memory_min);

static void unit_set_xattr_graceful(Unit *u, const char *name, const void *data, size_t size) {
        int r;

        assert(u);
        assert(name);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return;

        r = cg_set_xattr(crt->cgroup_path, name, data, size, 0);
        if (r < 0)
                log_unit_debug_errno(u, r, "Failed to set '%s' xattr on control group %s, ignoring: %m", name, empty_to_root(crt->cgroup_path));
}

static void unit_remove_xattr_graceful(Unit *u, const char *name) {
        int r;

        assert(u);
        assert(name);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return;

        r = cg_remove_xattr(crt->cgroup_path, name);
        if (r < 0 && !ERRNO_IS_XATTR_ABSENT(r))
                log_unit_debug_errno(u, r, "Failed to remove '%s' xattr flag on control group %s, ignoring: %m", name, empty_to_root(crt->cgroup_path));
}

static void cgroup_oomd_xattr_apply(Unit *u) {
        CGroupContext *c;

        assert(u);

        c = unit_get_cgroup_context(u);
        if (!c)
                return;

        if (c->moom_preference == MANAGED_OOM_PREFERENCE_OMIT)
                unit_set_xattr_graceful(u, "user.oomd_omit", "1", 1);

        if (c->moom_preference == MANAGED_OOM_PREFERENCE_AVOID)
                unit_set_xattr_graceful(u, "user.oomd_avoid", "1", 1);

        if (c->moom_preference != MANAGED_OOM_PREFERENCE_AVOID)
                unit_remove_xattr_graceful(u, "user.oomd_avoid");

        if (c->moom_preference != MANAGED_OOM_PREFERENCE_OMIT)
                unit_remove_xattr_graceful(u, "user.oomd_omit");
}

static int cgroup_log_xattr_apply(Unit *u) {
        ExecContext *c;
        size_t len, allowed_patterns_len, denied_patterns_len;
        _cleanup_free_ char *patterns = NULL, *allowed_patterns = NULL, *denied_patterns = NULL;
        char *last;
        int r;

        assert(u);

        c = unit_get_exec_context(u);
        if (!c)
                /* Some unit types have a cgroup context but no exec context, so we do not log
                 * any error here to avoid confusion. */
                return 0;

        if (set_isempty(c->log_filter_allowed_patterns) && set_isempty(c->log_filter_denied_patterns)) {
                unit_remove_xattr_graceful(u, "user.journald_log_filter_patterns");
                return 0;
        }

        r = set_make_nulstr(c->log_filter_allowed_patterns, &allowed_patterns, &allowed_patterns_len);
        if (r < 0)
                return log_debug_errno(r, "Failed to make nulstr from set: %m");

        r = set_make_nulstr(c->log_filter_denied_patterns, &denied_patterns, &denied_patterns_len);
        if (r < 0)
                return log_debug_errno(r, "Failed to make nulstr from set: %m");

        /* Use nul character separated strings without trailing nul */
        allowed_patterns_len = LESS_BY(allowed_patterns_len, 1u);
        denied_patterns_len = LESS_BY(denied_patterns_len, 1u);

        len = allowed_patterns_len + 1 + denied_patterns_len;
        patterns = new(char, len);
        if (!patterns)
                return log_oom_debug();

        last = mempcpy_safe(patterns, allowed_patterns, allowed_patterns_len);
        *(last++) = '\xff';
        memcpy_safe(last, denied_patterns, denied_patterns_len);

        unit_set_xattr_graceful(u, "user.journald_log_filter_patterns", patterns, len);

        return 0;
}

static void cgroup_invocation_id_xattr_apply(Unit *u) {
        bool b;

        assert(u);

        b = !sd_id128_is_null(u->invocation_id);
        FOREACH_STRING(xn, "trusted.invocation_id", "user.invocation_id") {
                if (b)
                        unit_set_xattr_graceful(u, xn, SD_ID128_TO_STRING(u->invocation_id), 32);
                else
                        unit_remove_xattr_graceful(u, xn);
        }
}

static void cgroup_coredump_xattr_apply(Unit *u) {
        CGroupContext *c;

        assert(u);

        c = unit_get_cgroup_context(u);
        if (!c)
                return;

        if (unit_cgroup_delegate(u) && c->coredump_receive)
                unit_set_xattr_graceful(u, "user.coredump_receive", "1", 1);
        else
                unit_remove_xattr_graceful(u, "user.coredump_receive");
}

static void cgroup_delegate_xattr_apply(Unit *u) {
        bool b;

        assert(u);

        /* Indicate on the cgroup whether delegation is on, via an xattr. This is best-effort, as old kernels
         * didn't support xattrs on cgroups at all. Later they got support for setting 'trusted.*' xattrs,
         * and even later 'user.*' xattrs. We started setting this field when 'trusted.*' was added, and
         * given this is now pretty much API, let's continue to support that. But also set 'user.*' as well,
         * since it is readable by any user, not just CAP_SYS_ADMIN. This hence comes with slightly weaker
         * security (as users who got delegated cgroups could turn it off if they like), but this shouldn't
         * be a big problem given this communicates delegation state to clients, but the manager never reads
         * it. */
        b = unit_cgroup_delegate(u);
        FOREACH_STRING(xn, "trusted.delegate", "user.delegate") {
                if (b)
                        unit_set_xattr_graceful(u, xn, "1", 1);
                else
                        unit_remove_xattr_graceful(u, xn);
        }
}

static void cgroup_survive_xattr_apply(Unit *u) {
        int r;

        assert(u);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return;

        if (u->survive_final_kill_signal) {
                r = cg_set_xattr(
                                crt->cgroup_path,
                                "user.survive_final_kill_signal",
                                "1",
                                1,
                                /* flags= */ 0);
                /* user xattr support was added in kernel v5.7 */
                if (ERRNO_IS_NEG_NOT_SUPPORTED(r))
                        r = cg_set_xattr(
                                        crt->cgroup_path,
                                        "trusted.survive_final_kill_signal",
                                        "1",
                                        1,
                                        /* flags= */ 0);
                if (r < 0)
                        log_unit_debug_errno(u,
                                             r,
                                             "Failed to set 'survive_final_kill_signal' xattr on control "
                                             "group %s, ignoring: %m",
                                             empty_to_root(crt->cgroup_path));
        } else {
                unit_remove_xattr_graceful(u, "user.survive_final_kill_signal");
                unit_remove_xattr_graceful(u, "trusted.survive_final_kill_signal");
        }
}

static void cgroup_xattr_apply(Unit *u) {
        assert(u);

        /* The 'user.*' xattrs can be set from a user manager. */
        cgroup_oomd_xattr_apply(u);
        cgroup_log_xattr_apply(u);
        cgroup_coredump_xattr_apply(u);

        if (!MANAGER_IS_SYSTEM(u->manager))
                return;

        cgroup_invocation_id_xattr_apply(u);
        cgroup_delegate_xattr_apply(u);
        cgroup_survive_xattr_apply(u);
}

static int lookup_block_device(const char *p, dev_t *ret) {
        dev_t rdev, dev = 0;
        mode_t mode;
        int r;

        assert(p);
        assert(ret);

        r = device_path_parse_major_minor(p, &mode, &rdev);
        if (r == -ENODEV) { /* not a parsable device node, need to go to disk */
                struct stat st;

                if (stat(p, &st) < 0)
                        return log_warning_errno(errno, "Couldn't stat device '%s': %m", p);

                mode = st.st_mode;
                rdev = st.st_rdev;
                dev = st.st_dev;
        } else if (r < 0)
                return log_warning_errno(r, "Failed to parse major/minor from path '%s': %m", p);

        if (S_ISCHR(mode))
                return log_warning_errno(SYNTHETIC_ERRNO(ENOTBLK),
                                         "Device node '%s' is a character device, but block device needed.", p);
        if (S_ISBLK(mode))
                *ret = rdev;
        else if (major(dev) != 0)
                *ret = dev; /* If this is not a device node then use the block device this file is stored on */
        else {
                /* If this is btrfs, getting the backing block device is a bit harder */
                r = btrfs_get_block_device(p, ret);
                if (r == -ENOTTY)
                        return log_warning_errno(SYNTHETIC_ERRNO(ENODEV),
                                                 "'%s' is not a block device node, and file system block device cannot be determined or is not local.", p);
                if (r < 0)
                        return log_warning_errno(r, "Failed to determine block device backing btrfs file system '%s': %m", p);
        }

        /* If this is a LUKS/DM device, recursively try to get the originating block device */
        while (block_get_originating(*ret, ret) >= 0)
                ;

        /* If this is a partition, try to get the originating block device */
        (void) block_get_whole_disk(*ret, ret);
        return 0;
}

static bool cgroup_context_has_cpu_weight(CGroupContext *c) {
        return c->cpu_weight != CGROUP_WEIGHT_INVALID ||
                c->startup_cpu_weight != CGROUP_WEIGHT_INVALID;
}

static bool cgroup_context_has_allowed_cpus(CGroupContext *c) {
        return c->cpuset_cpus.set || c->startup_cpuset_cpus.set;
}

static bool cgroup_context_has_allowed_mems(CGroupContext *c) {
        return c->cpuset_mems.set || c->startup_cpuset_mems.set;
}

uint64_t cgroup_context_cpu_weight(CGroupContext *c, ManagerState state) {
        assert(c);

        if (IN_SET(state, MANAGER_STARTING, MANAGER_INITIALIZING, MANAGER_STOPPING) &&
            c->startup_cpu_weight != CGROUP_WEIGHT_INVALID)
                return c->startup_cpu_weight;
        else if (c->cpu_weight != CGROUP_WEIGHT_INVALID)
                return c->cpu_weight;
        else
                return CGROUP_WEIGHT_DEFAULT;
}

static CPUSet *cgroup_context_allowed_cpus(CGroupContext *c, ManagerState state) {
        if (IN_SET(state, MANAGER_STARTING, MANAGER_INITIALIZING, MANAGER_STOPPING) &&
            c->startup_cpuset_cpus.set)
                return &c->startup_cpuset_cpus;
        else
                return &c->cpuset_cpus;
}

static CPUSet *cgroup_context_allowed_mems(CGroupContext *c, ManagerState state) {
        if (IN_SET(state, MANAGER_STARTING, MANAGER_INITIALIZING, MANAGER_STOPPING) &&
            c->startup_cpuset_mems.set)
                return &c->startup_cpuset_mems;
        else
                return &c->cpuset_mems;
}

usec_t cgroup_cpu_adjust_period(usec_t period, usec_t quota, usec_t resolution, usec_t max_period) {
        /* kernel uses a minimum resolution of 1ms, so both period and (quota * period)
         * need to be higher than that boundary. quota is specified in USecPerSec.
         * Additionally, period must be at most max_period. */
        assert(quota > 0);

        return MIN(MAX3(period, resolution, resolution * USEC_PER_SEC / quota), max_period);
}

static usec_t cgroup_cpu_adjust_period_and_log(Unit *u, usec_t period, usec_t quota) {
        usec_t new_period;

        assert(u);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return USEC_INFINITY;

        if (quota == USEC_INFINITY)
                /* Always use default period for infinity quota. */
                return CGROUP_CPU_QUOTA_DEFAULT_PERIOD_USEC;

        if (period == USEC_INFINITY)
                /* Default period was requested. */
                period = CGROUP_CPU_QUOTA_DEFAULT_PERIOD_USEC;

        /* Clamp to interval [1ms, 1s] */
        new_period = cgroup_cpu_adjust_period(period, quota, USEC_PER_MSEC, USEC_PER_SEC);

        if (new_period != period) {
                log_unit_full(u, crt->warned_clamping_cpu_quota_period ? LOG_DEBUG : LOG_WARNING,
                              "Clamping CPU interval for cpu.max: period is now %s",
                              FORMAT_TIMESPAN(new_period, 1));
                crt->warned_clamping_cpu_quota_period = true;
        }

        return new_period;
}

static void cgroup_apply_cpu_weight(Unit *u, uint64_t weight) {
        char buf[DECIMAL_STR_MAX(uint64_t) + 2];

        if (weight == CGROUP_WEIGHT_IDLE)
                return;
        xsprintf(buf, "%" PRIu64 "\n", weight);
        (void) set_attribute_and_warn(u, "cpu.weight", buf);
}

static void cgroup_apply_cpu_idle(Unit *u, uint64_t weight) {
        int r;
        bool is_idle;
        const char *idle_val;

        assert(u);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return;

        is_idle = weight == CGROUP_WEIGHT_IDLE;
        idle_val = one_zero(is_idle);
        r = cg_set_attribute("cpu", crt->cgroup_path, "cpu.idle", idle_val);
        if (r < 0 && (r != -ENOENT || is_idle))
                log_unit_full_errno(u, LOG_LEVEL_CGROUP_WRITE(r), r, "Failed to set '%s' attribute on '%s' to '%s': %m",
                                    "cpu.idle", empty_to_root(crt->cgroup_path), idle_val);
}

static void cgroup_apply_cpu_quota(Unit *u, usec_t quota, usec_t period) {
        char buf[(DECIMAL_STR_MAX(usec_t) + 1) * 2 + 1];

        assert(u);

        period = cgroup_cpu_adjust_period_and_log(u, period, quota);
        if (quota != USEC_INFINITY)
                xsprintf(buf, USEC_FMT " " USEC_FMT "\n",
                         MAX(quota * period / USEC_PER_SEC, USEC_PER_MSEC), period);
        else
                xsprintf(buf, "max " USEC_FMT "\n", period);
        (void) set_attribute_and_warn(u, "cpu.max", buf);
}

static void cgroup_apply_cpuset(Unit *u, const CPUSet *cpus, const char *name) {
        _cleanup_free_ char *buf = NULL;

        buf = cpu_set_to_range_string(cpus);
        if (!buf) {
                log_oom();
                return;
        }

        (void) set_attribute_and_warn(u, name, buf);
}

static bool cgroup_context_has_io_config(CGroupContext *c) {
        return c->io_accounting ||
                c->io_weight != CGROUP_WEIGHT_INVALID ||
                c->startup_io_weight != CGROUP_WEIGHT_INVALID ||
                c->io_device_weights ||
                c->io_device_latencies ||
                c->io_device_limits;
}

static uint64_t cgroup_context_io_weight(CGroupContext *c, ManagerState state) {
        if (IN_SET(state, MANAGER_STARTING, MANAGER_INITIALIZING, MANAGER_STOPPING) &&
            c->startup_io_weight != CGROUP_WEIGHT_INVALID)
                return c->startup_io_weight;
        if (c->io_weight != CGROUP_WEIGHT_INVALID)
                return c->io_weight;
        return CGROUP_WEIGHT_DEFAULT;
}

static int set_bfq_weight(Unit *u, dev_t dev, uint64_t io_weight) {
        char buf[DECIMAL_STR_MAX(dev_t)*2+2+DECIMAL_STR_MAX(uint64_t)+STRLEN("\n")];
        uint64_t bfq_weight;
        int r;

        assert(u);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return -EOWNERDEAD;

        /* FIXME: drop this function when distro kernels properly support BFQ through "io.weight"
         * See also: https://github.com/systemd/systemd/pull/13335 and
         * https://github.com/torvalds/linux/commit/65752aef0a407e1ef17ec78a7fc31ba4e0b360f9. */
        /* Adjust to kernel range is 1..1000, the default is 100. */
        bfq_weight = BFQ_WEIGHT(io_weight);

        if (major(dev) > 0)
                xsprintf(buf, DEVNUM_FORMAT_STR " %" PRIu64 "\n", DEVNUM_FORMAT_VAL(dev), bfq_weight);
        else
                xsprintf(buf, "%" PRIu64 "\n", bfq_weight);

        r = cg_set_attribute(SYSTEMD_CGROUP_CONTROLLER, crt->cgroup_path, "io.bfq.weight", buf);
        if (r >= 0 && io_weight != bfq_weight)
                log_unit_debug(u, "%s=%" PRIu64 " scaled to io.bfq.weight=%" PRIu64,
                               major(dev) > 0 ? "IODeviceWeight" : "IOWeight",
                               io_weight, bfq_weight);
        return r;
}

static void cgroup_apply_io_device_weight(Unit *u, const char *dev_path, uint64_t io_weight) {
        char buf[DECIMAL_STR_MAX(dev_t)*2+2+DECIMAL_STR_MAX(uint64_t)+1];
        dev_t dev;
        int r, r1, r2;

        assert(u);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return;

        if (lookup_block_device(dev_path, &dev) < 0)
                return;

        r1 = set_bfq_weight(u, dev, io_weight);

        xsprintf(buf, DEVNUM_FORMAT_STR " %" PRIu64 "\n", DEVNUM_FORMAT_VAL(dev), io_weight);
        r2 = cg_set_attribute("io", crt->cgroup_path, "io.weight", buf);

        /* Look at the configured device, when both fail, prefer io.weight errno. */
        r = r2 == -EOPNOTSUPP ? r1 : r2;

        if (r < 0)
                log_unit_full_errno(u, LOG_LEVEL_CGROUP_WRITE(r),
                                    r, "Failed to set 'io[.bfq].weight' attribute on '%s' to '%.*s': %m",
                                    empty_to_root(crt->cgroup_path), (int) strcspn(buf, NEWLINE), buf);
}

static void cgroup_apply_io_device_latency(Unit *u, const char *dev_path, usec_t target) {
        char buf[DECIMAL_STR_MAX(dev_t)*2+2+7+DECIMAL_STR_MAX(uint64_t)+1];
        dev_t dev;
        int r;

        r = lookup_block_device(dev_path, &dev);
        if (r < 0)
                return;

        if (target != USEC_INFINITY)
                xsprintf(buf, DEVNUM_FORMAT_STR " target=%" PRIu64 "\n", DEVNUM_FORMAT_VAL(dev), target);
        else
                xsprintf(buf, DEVNUM_FORMAT_STR " target=max\n", DEVNUM_FORMAT_VAL(dev));

        (void) set_attribute_and_warn(u, "io.latency", buf);
}

static void cgroup_apply_io_device_limit(Unit *u, const char *dev_path, uint64_t *limits) {
        char limit_bufs[_CGROUP_IO_LIMIT_TYPE_MAX][DECIMAL_STR_MAX(uint64_t)],
             buf[DECIMAL_STR_MAX(dev_t)*2+2+(6+DECIMAL_STR_MAX(uint64_t)+1)*4];
        dev_t dev;

        if (lookup_block_device(dev_path, &dev) < 0)
                return;

        for (CGroupIOLimitType type = 0; type < _CGROUP_IO_LIMIT_TYPE_MAX; type++)
                if (limits[type] != cgroup_io_limit_defaults[type])
                        xsprintf(limit_bufs[type], "%" PRIu64, limits[type]);
                else
                        xsprintf(limit_bufs[type], "%s", limits[type] == CGROUP_LIMIT_MAX ? "max" : "0");

        xsprintf(buf, DEVNUM_FORMAT_STR " rbps=%s wbps=%s riops=%s wiops=%s\n", DEVNUM_FORMAT_VAL(dev),
                 limit_bufs[CGROUP_IO_RBPS_MAX], limit_bufs[CGROUP_IO_WBPS_MAX],
                 limit_bufs[CGROUP_IO_RIOPS_MAX], limit_bufs[CGROUP_IO_WIOPS_MAX]);
        (void) set_attribute_and_warn(u, "io.max", buf);
}

static bool unit_has_memory_config(Unit *u) {
        CGroupContext *c;

        assert(u);

        assert_se(c = unit_get_cgroup_context(u));

        return unit_get_ancestor_memory_min(u) > 0 ||
               unit_get_ancestor_memory_low(u) > 0 || unit_get_ancestor_startup_memory_low(u) > 0 ||
               c->memory_high != CGROUP_LIMIT_MAX || c->startup_memory_high_set ||
               c->memory_max != CGROUP_LIMIT_MAX || c->startup_memory_max_set ||
               c->memory_swap_max != CGROUP_LIMIT_MAX || c->startup_memory_swap_max_set ||
               c->memory_zswap_max != CGROUP_LIMIT_MAX || c->startup_memory_zswap_max_set;
}

static void cgroup_apply_memory_limit(Unit *u, const char *file, uint64_t v) {
        char buf[DECIMAL_STR_MAX(uint64_t) + 1] = "max\n";

        if (v != CGROUP_LIMIT_MAX)
                xsprintf(buf, "%" PRIu64 "\n", v);

        (void) set_attribute_and_warn(u, file, buf);
}

static void cgroup_apply_firewall(Unit *u) {
        assert(u);

        /* Best-effort: let's apply IP firewalling and/or accounting if that's enabled */

        if (bpf_firewall_compile(u) < 0)
                return;

        (void) bpf_firewall_load_custom(u);
        (void) bpf_firewall_install(u);
}

void unit_modify_nft_set(Unit *u, bool add) {
        int r;

        assert(u);

        if (!MANAGER_IS_SYSTEM(u->manager))
                return;

        if (!UNIT_HAS_CGROUP_CONTEXT(u))
                return;

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || crt->cgroup_id == 0)
                return;

        if (!u->manager->nfnl) {
                r = sd_nfnl_socket_open(&u->manager->nfnl);
                if (r < 0)
                        return;
        }

        CGroupContext *c = ASSERT_PTR(unit_get_cgroup_context(u));

        FOREACH_ARRAY(nft_set, c->nft_set_context.sets, c->nft_set_context.n_sets) {
                if (nft_set->source != NFT_SET_SOURCE_CGROUP)
                        continue;

                uint64_t element = crt->cgroup_id;

                r = nft_set_element_modify_any(u->manager->nfnl, add, nft_set->nfproto, nft_set->table, nft_set->set, &element, sizeof(element));
                if (r < 0)
                        log_warning_errno(r, "Failed to %s NFT set entry: family %s, table %s, set %s, cgroup %" PRIu64 ", ignoring: %m",
                                          add? "add" : "delete", nfproto_to_string(nft_set->nfproto), nft_set->table, nft_set->set, crt->cgroup_id);
                else
                        log_debug("%s NFT set entry: family %s, table %s, set %s, cgroup %" PRIu64,
                                  add? "Added" : "Deleted", nfproto_to_string(nft_set->nfproto), nft_set->table, nft_set->set, crt->cgroup_id);
        }
}

static void cgroup_apply_socket_bind(Unit *u) {
        assert(u);

        (void) bpf_socket_bind_install(u);
}

static void cgroup_apply_restrict_network_interfaces(Unit *u) {
        assert(u);

        (void) bpf_restrict_ifaces_install(u);
}

static int cgroup_apply_devices(Unit *u) {
        _cleanup_(bpf_program_freep) BPFProgram *prog = NULL;
        CGroupContext *c;
        CGroupDevicePolicy policy;
        int r;

        assert_se(c = unit_get_cgroup_context(u));

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return -EOWNERDEAD;

        policy = c->device_policy;

        r = bpf_devices_cgroup_init(&prog, policy, c->device_allow);
        if (r < 0)
                return log_unit_warning_errno(u, r, "Failed to initialize device control bpf program: %m");

        bool allow_list_static = policy == CGROUP_DEVICE_POLICY_CLOSED ||
                (policy == CGROUP_DEVICE_POLICY_AUTO && c->device_allow);

        bool any = false;
        if (allow_list_static) {
                r = bpf_devices_allow_list_static(prog, crt->cgroup_path);
                if (r > 0)
                        any = true;
        }

        LIST_FOREACH(device_allow, a, c->device_allow) {
                const char *val;

                if (a->permissions == 0)
                        continue;

                if (path_startswith(a->path, "/dev/"))
                        r = bpf_devices_allow_list_device(prog, crt->cgroup_path, a->path, a->permissions);
                else if ((val = startswith(a->path, "block-")))
                        r = bpf_devices_allow_list_major(prog, crt->cgroup_path, val, 'b', a->permissions);
                else if ((val = startswith(a->path, "char-")))
                        r = bpf_devices_allow_list_major(prog, crt->cgroup_path, val, 'c', a->permissions);
                else {
                        log_unit_debug(u, "Ignoring device '%s' while writing cgroup attribute.", a->path);
                        continue;
                }

                if (r > 0)
                        any = true;
        }

        if (prog && !any) {
                log_unit_warning(u, "No devices matched by device filter.");

                /* The kernel verifier would reject a program we would build with the normal intro and outro
                   but no allow-listing rules (outro would contain an unreachable instruction for successful
                   return). */
                policy = CGROUP_DEVICE_POLICY_STRICT;
        }

        r = bpf_devices_apply_policy(&prog, policy, any, crt->cgroup_path, &crt->bpf_device_control_installed);
        if (r < 0) {
                static bool warned = false;

                log_full_errno(warned ? LOG_DEBUG : LOG_WARNING, r,
                               "Unit %s configures device ACL, but the local system doesn't seem to support the BPF-based device controller.\n"
                               "Proceeding WITHOUT applying ACL (all devices will be accessible)!\n"
                               "(This warning is only shown for the first loaded unit using device ACL.)", u->id);

                warned = true;
        }
        return r;
}

static void set_io_weight(Unit *u, uint64_t weight) {
        char buf[STRLEN("default \n")+DECIMAL_STR_MAX(uint64_t)];

        assert(u);

        (void) set_bfq_weight(u, makedev(0, 0), weight);

        xsprintf(buf, "default %" PRIu64 "\n", weight);
        (void) set_attribute_and_warn(u, "io.weight", buf);
}

static void cgroup_context_apply(
                Unit *u,
                CGroupMask apply_mask,
                ManagerState state) {

        bool is_host_root, is_local_root;
        CGroupContext *c;
        int r;

        assert(u);

        /* Nothing to do? Exit early! */
        if (apply_mask == 0)
                return;

        /* Some cgroup attributes are not supported on the host root cgroup, hence silently ignore them here. And other
         * attributes should only be managed for cgroups further down the tree. */
        is_local_root = unit_has_name(u, SPECIAL_ROOT_SLICE);
        is_host_root = unit_has_host_root_cgroup(u);

        assert_se(c = unit_get_cgroup_context(u));

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return;

        /* We generally ignore errors caused by read-only mounted cgroup trees (assuming we are running in a container
         * then), and missing cgroups, i.e. EROFS and ENOENT. */

        /* These attributes don't exist on the host cgroup root. */
        if ((apply_mask & CGROUP_MASK_CPU) && !is_local_root) {
                uint64_t weight;

                if (cgroup_context_has_cpu_weight(c))
                        weight = cgroup_context_cpu_weight(c, state);
                else
                        weight = CGROUP_WEIGHT_DEFAULT;

                cgroup_apply_cpu_idle(u, weight);
                cgroup_apply_cpu_weight(u, weight);
                cgroup_apply_cpu_quota(u, c->cpu_quota_per_sec_usec, c->cpu_quota_period_usec);
        }

        if ((apply_mask & CGROUP_MASK_CPUSET) && !is_local_root) {
                cgroup_apply_cpuset(u, cgroup_context_allowed_cpus(c, state), "cpuset.cpus");
                cgroup_apply_cpuset(u, cgroup_context_allowed_mems(c, state), "cpuset.mems");
        }

        /* The 'io' controller attributes are not exported on the host's root cgroup (being a pure cgroup v2
         * controller), and in case of containers we want to leave control of these attributes to the container manager
         * (and we couldn't access that stuff anyway, even if we tried if proper delegation is used). */
        if ((apply_mask & CGROUP_MASK_IO) && !is_local_root) {
                bool has_io;
                uint64_t weight;

                has_io = cgroup_context_has_io_config(c);

                if (has_io)
                        weight = cgroup_context_io_weight(c, state);
                else
                        weight = CGROUP_WEIGHT_DEFAULT;

                set_io_weight(u, weight);

                if (has_io) {
                        LIST_FOREACH(device_weights, w, c->io_device_weights)
                                cgroup_apply_io_device_weight(u, w->path, w->weight);

                        LIST_FOREACH(device_limits, limit, c->io_device_limits)
                                cgroup_apply_io_device_limit(u, limit->path, limit->limits);

                        LIST_FOREACH(device_latencies, latency, c->io_device_latencies)
                                cgroup_apply_io_device_latency(u, latency->path, latency->target_usec);
                }
        }

        /* 'memory' attributes do not exist on the root cgroup. */
        if ((apply_mask & CGROUP_MASK_MEMORY) && !is_local_root) {
                uint64_t max = CGROUP_LIMIT_MAX, swap_max = CGROUP_LIMIT_MAX, zswap_max = CGROUP_LIMIT_MAX, high = CGROUP_LIMIT_MAX;

                if (unit_has_memory_config(u)) {
                        bool startup = IN_SET(state, MANAGER_STARTING, MANAGER_INITIALIZING, MANAGER_STOPPING);

                        high = startup && c->startup_memory_high_set ? c->startup_memory_high : c->memory_high;
                        max = startup && c->startup_memory_max_set ? c->startup_memory_max : c->memory_max;
                        swap_max = startup && c->startup_memory_swap_max_set ? c->startup_memory_swap_max : c->memory_swap_max;
                        zswap_max = startup && c->startup_memory_zswap_max_set ? c->startup_memory_zswap_max : c->memory_zswap_max;
                }

                cgroup_apply_memory_limit(u, "memory.min", unit_get_ancestor_memory_min(u));
                cgroup_apply_memory_limit(u, "memory.low", unit_get_ancestor_memory_low(u));
                cgroup_apply_memory_limit(u, "memory.high", high);
                cgroup_apply_memory_limit(u, "memory.max", max);
                cgroup_apply_memory_limit(u, "memory.swap.max", swap_max);
                cgroup_apply_memory_limit(u, "memory.zswap.max", zswap_max);

                (void) set_attribute_and_warn(u, "memory.oom.group", one_zero(c->memory_oom_group));
                (void) set_attribute_and_warn(u, "memory.zswap.writeback", one_zero(c->memory_zswap_writeback));
        }

        if (apply_mask & CGROUP_MASK_PIDS) {

                if (is_host_root) {
                        /* So, the "pids" controller does not expose anything on the root cgroup, in order not to
                         * replicate knobs exposed elsewhere needlessly. We abstract this away here however, and when
                         * the knobs of the root cgroup are modified propagate this to the relevant sysctls. There's a
                         * non-obvious asymmetry however: unlike the cgroup properties we don't really want to take
                         * exclusive ownership of the sysctls, but we still want to honour things if the user sets
                         * limits. Hence we employ sort of a one-way strategy: when the user sets a bounded limit
                         * through us it counts. When the user afterwards unsets it again (i.e. sets it to unbounded)
                         * it also counts. But if the user never set a limit through us (i.e. we are the default of
                         * "unbounded") we leave things unmodified. For this we manage a global boolean that we turn on
                         * the first time we set a limit. Note that this boolean is flushed out on manager reload,
                         * which is desirable so that there's an official way to release control of the sysctl from
                         * systemd: set the limit to unbounded and reload. */

                        if (cgroup_tasks_max_isset(&c->tasks_max)) {
                                u->manager->sysctl_pid_max_changed = true;
                                r = procfs_tasks_set_limit(cgroup_tasks_max_resolve(&c->tasks_max));
                        } else if (u->manager->sysctl_pid_max_changed)
                                r = procfs_tasks_set_limit(TASKS_MAX);
                        else
                                r = 0;
                        if (r < 0)
                                log_unit_full_errno(u, LOG_LEVEL_CGROUP_WRITE(r), r,
                                                    "Failed to write to tasks limit sysctls: %m");
                }

                /* The attribute itself is not available on the host root cgroup, and in the container case we want to
                 * leave it for the container manager. */
                if (!is_local_root) {
                        if (cgroup_tasks_max_isset(&c->tasks_max)) {
                                char buf[DECIMAL_STR_MAX(uint64_t) + 1];

                                xsprintf(buf, "%" PRIu64 "\n", cgroup_tasks_max_resolve(&c->tasks_max));
                                (void) set_attribute_and_warn(u, "pids.max", buf);
                        } else
                                (void) set_attribute_and_warn(u, "pids.max", "max\n");
                }
        }

        /* On cgroup v2 we can apply BPF everywhere. */
        if (apply_mask & CGROUP_MASK_BPF_DEVICES)
                (void) cgroup_apply_devices(u);

        if (apply_mask & CGROUP_MASK_BPF_FIREWALL)
                cgroup_apply_firewall(u);

        if (apply_mask & CGROUP_MASK_BPF_FOREIGN)
                (void) bpf_foreign_install(u);

        if (apply_mask & CGROUP_MASK_BPF_SOCKET_BIND)
                cgroup_apply_socket_bind(u);

        if (apply_mask & CGROUP_MASK_BPF_RESTRICT_NETWORK_INTERFACES)
                cgroup_apply_restrict_network_interfaces(u);

        unit_modify_nft_set(u, /* add = */ true);
}

static bool unit_get_needs_bpf_firewall(Unit *u) {
        CGroupContext *c;
        assert(u);

        c = unit_get_cgroup_context(u);
        if (!c)
                return false;

        if (c->ip_accounting ||
            !set_isempty(c->ip_address_allow) ||
            !set_isempty(c->ip_address_deny) ||
            c->ip_filters_ingress ||
            c->ip_filters_egress)
                return true;

        /* If any parent slice has an IP access list defined, it applies too */
        for (Unit *p = UNIT_GET_SLICE(u); p; p = UNIT_GET_SLICE(p)) {
                c = unit_get_cgroup_context(p);
                if (!c)
                        return false;

                if (!set_isempty(c->ip_address_allow) ||
                    !set_isempty(c->ip_address_deny))
                        return true;
        }

        return false;
}

static bool unit_get_needs_bpf_foreign_program(Unit *u) {
        CGroupContext *c;
        assert(u);

        c = unit_get_cgroup_context(u);
        if (!c)
                return false;

        return !!c->bpf_foreign_programs;
}

static bool unit_get_needs_socket_bind(Unit *u) {
        CGroupContext *c;
        assert(u);

        c = unit_get_cgroup_context(u);
        if (!c)
                return false;

        return c->socket_bind_allow || c->socket_bind_deny;
}

static bool unit_get_needs_restrict_network_interfaces(Unit *u) {
        CGroupContext *c;
        assert(u);

        c = unit_get_cgroup_context(u);
        if (!c)
                return false;

        return !set_isempty(c->restrict_network_interfaces);
}

static CGroupMask unit_get_cgroup_mask(Unit *u) {
        CGroupMask mask = 0;
        CGroupContext *c;

        assert(u);

        assert_se(c = unit_get_cgroup_context(u));

        /* Figure out which controllers we need, based on the cgroup context object */

        if (cgroup_context_has_cpu_weight(c) ||
            c->cpu_quota_per_sec_usec != USEC_INFINITY)
                mask |= CGROUP_MASK_CPU;

        if (cgroup_context_has_allowed_cpus(c) || cgroup_context_has_allowed_mems(c))
                mask |= CGROUP_MASK_CPUSET;

        if (cgroup_context_has_io_config(c))
                mask |= CGROUP_MASK_IO;

        if (c->memory_accounting ||
            unit_has_memory_config(u))
                mask |= CGROUP_MASK_MEMORY;

        if (cgroup_context_has_device_policy(c))
                mask |= CGROUP_MASK_BPF_DEVICES;

        if (c->tasks_accounting ||
            cgroup_tasks_max_isset(&c->tasks_max))
                mask |= CGROUP_MASK_PIDS;

        return mask;
}

static CGroupMask unit_get_bpf_mask(Unit *u) {
        CGroupMask mask = 0;

        /* Figure out which controllers we need, based on the cgroup context, possibly taking into account children
         * too. */

        if (unit_get_needs_bpf_firewall(u))
                mask |= CGROUP_MASK_BPF_FIREWALL;

        if (unit_get_needs_bpf_foreign_program(u))
                mask |= CGROUP_MASK_BPF_FOREIGN;

        if (unit_get_needs_socket_bind(u))
                mask |= CGROUP_MASK_BPF_SOCKET_BIND;

        if (unit_get_needs_restrict_network_interfaces(u))
                mask |= CGROUP_MASK_BPF_RESTRICT_NETWORK_INTERFACES;

        return mask;
}

CGroupMask unit_get_own_mask(Unit *u) {
        CGroupContext *c;

        /* Returns the mask of controllers the unit needs for itself. If a unit is not properly loaded, return an empty
         * mask, as we shouldn't reflect it in the cgroup hierarchy then. */

        if (u->load_state != UNIT_LOADED)
                return 0;

        c = unit_get_cgroup_context(u);
        if (!c)
                return 0;

        return unit_get_cgroup_mask(u) | unit_get_bpf_mask(u) | unit_get_delegate_mask(u);
}

CGroupMask unit_get_delegate_mask(Unit *u) {
        CGroupContext *c;

        /* If delegation is turned on, then turn on selected controllers.
         *
         * Note that on the unified hierarchy it is safe to delegate controllers to unprivileged services. */

        if (!unit_cgroup_delegate(u))
                return 0;

        assert_se(c = unit_get_cgroup_context(u));
        return c->delegate_controllers;
}

static CGroupMask unit_get_subtree_mask(Unit *u) {

        /* Returns the mask of this subtree, meaning of the group
         * itself and its children. */

        return unit_get_own_mask(u) | unit_get_members_mask(u);
}

CGroupMask unit_get_members_mask(Unit *u) {
        assert(u);

        /* Returns the mask of controllers all of the unit's children require, merged */

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (crt && crt->cgroup_members_mask_valid)
                return crt->cgroup_members_mask; /* Use cached value if possible */

        CGroupMask m = 0;
        if (u->type == UNIT_SLICE) {
                Unit *member;

                UNIT_FOREACH_DEPENDENCY(member, u, UNIT_ATOM_SLICE_OF)
                        m |= unit_get_subtree_mask(member); /* note that this calls ourselves again, for the children */
        }

        if (crt) {
                crt->cgroup_members_mask = m;
                crt->cgroup_members_mask_valid = true;
        }

        return m;
}

CGroupMask unit_get_siblings_mask(Unit *u) {
        Unit *slice;
        assert(u);

        /* Returns the mask of controllers all of the unit's siblings
         * require, i.e. the members mask of the unit's parent slice
         * if there is one. */

        slice = UNIT_GET_SLICE(u);
        if (slice)
                return unit_get_members_mask(slice);

        return unit_get_subtree_mask(u); /* we are the top-level slice */
}

static CGroupMask unit_get_disable_mask(Unit *u) {
        CGroupContext *c;

        c = unit_get_cgroup_context(u);
        if (!c)
                return 0;

        return c->disable_controllers;
}

static CGroupMask unit_get_ancestor_disable_mask(Unit *u) {
        CGroupMask mask;
        Unit *slice;

        assert(u);
        mask = unit_get_disable_mask(u);

        /* Returns the mask of controllers which are marked as forcibly
         * disabled in any ancestor unit or the unit in question. */

        slice = UNIT_GET_SLICE(u);
        if (slice)
                mask |= unit_get_ancestor_disable_mask(slice);

        return mask;
}

CGroupMask unit_get_target_mask(Unit *u) {
        CGroupMask own_mask, mask;

        /* This returns the cgroup mask of all controllers to enable for a specific cgroup, i.e. everything
         * it needs itself, plus all that its children need, plus all that its siblings need. This is
         * primarily useful on the legacy cgroup hierarchy, where we need to duplicate each cgroup in each
         * hierarchy that shall be enabled for it. */

        own_mask = unit_get_own_mask(u);

        if (own_mask & CGROUP_MASK_BPF_FIREWALL & ~u->manager->cgroup_supported)
                emit_bpf_firewall_warning(u);

        mask = own_mask | unit_get_members_mask(u) | unit_get_siblings_mask(u);

        mask &= u->manager->cgroup_supported;
        mask &= ~unit_get_ancestor_disable_mask(u);

        return mask;
}

CGroupMask unit_get_enable_mask(Unit *u) {
        CGroupMask mask;

        /* This returns the cgroup mask of all controllers to enable
         * for the children of a specific cgroup. This is primarily
         * useful for the unified cgroup hierarchy, where each cgroup
         * controls which controllers are enabled for its children. */

        mask = unit_get_members_mask(u);
        mask &= u->manager->cgroup_supported;
        mask &= ~unit_get_ancestor_disable_mask(u);

        return mask;
}

void unit_invalidate_cgroup_members_masks(Unit *u) {
        Unit *slice;

        assert(u);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return;

        /* Recurse invalidate the member masks cache all the way up the tree */
        crt->cgroup_members_mask_valid = false;

        slice = UNIT_GET_SLICE(u);
        if (slice)
                unit_invalidate_cgroup_members_masks(slice);
}

static int unit_default_cgroup_path(const Unit *u, char **ret) {
        _cleanup_free_ char *p = NULL;
        int r;

        assert(u);
        assert(ret);

        if (unit_has_name(u, SPECIAL_ROOT_SLICE))
                p = strdup(u->manager->cgroup_root);
        else {
                _cleanup_free_ char *escaped = NULL, *slice_path = NULL;
                Unit *slice;

                slice = UNIT_GET_SLICE(u);
                if (slice && !unit_has_name(slice, SPECIAL_ROOT_SLICE)) {
                        r = cg_slice_to_path(slice->id, &slice_path);
                        if (r < 0)
                                return r;
                }

                r = cg_escape(u->id, &escaped);
                if (r < 0)
                        return r;

                p = path_join(empty_to_root(u->manager->cgroup_root), slice_path, escaped);
        }
        if (!p)
                return -ENOMEM;

        *ret = TAKE_PTR(p);
        return 0;
}

static int unit_set_cgroup_path(Unit *u, const char *path) {
        _cleanup_free_ char *p = NULL;
        CGroupRuntime *crt;
        int r;

        assert(u);

        crt = unit_get_cgroup_runtime(u);
        if (crt && streq_ptr(crt->cgroup_path, path))
                return 0;

        unit_release_cgroup(u, /* drop_cgroup_runtime = */ true);

        crt = unit_setup_cgroup_runtime(u);
        if (!crt)
                return -ENOMEM;

        if (path) {
                p = strdup(path);
                if (!p)
                        return -ENOMEM;

                r = hashmap_put(u->manager->cgroup_unit, p, u);
                if (r < 0)
                        return r;
        }

        assert(!crt->cgroup_path);
        crt->cgroup_path = TAKE_PTR(p);

        return 1;
}

int unit_get_cgroup_path_with_fallback(const Unit *u, char **ret) {
        assert(u);
        assert(ret);

        const CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return unit_default_cgroup_path(u, ret);

        return strdup_to_full(ret, crt->cgroup_path); /* returns 1 -> cgroup_path is alive */
}

static int unit_watch_cgroup(Unit *u) {
        _cleanup_free_ char *events = NULL;
        int r;

        assert(u);

        /* Watches the "cgroups.events" attribute of this unit's cgroup for "empty" events. */

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return 0;

        if (crt->cgroup_control_inotify_wd >= 0)
                return 0;

        /* No point in watch the top-level slice, it's never going to run empty. */
        if (unit_has_name(u, SPECIAL_ROOT_SLICE))
                return 0;

        r = hashmap_ensure_allocated(&u->manager->cgroup_control_inotify_wd_unit, &trivial_hash_ops);
        if (r < 0)
                return log_oom();

        r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, crt->cgroup_path, "cgroup.events", &events);
        if (r < 0)
                return log_oom();

        crt->cgroup_control_inotify_wd = inotify_add_watch(u->manager->cgroup_inotify_fd, events, IN_MODIFY);
        if (crt->cgroup_control_inotify_wd < 0) {

                if (errno == ENOENT) /* If the directory is already gone we don't need to track it, so this
                                      * is not an error */
                        return 0;

                return log_unit_error_errno(u, errno, "Failed to add control inotify watch descriptor for control group %s: %m", empty_to_root(crt->cgroup_path));
        }

        r = hashmap_put(u->manager->cgroup_control_inotify_wd_unit, INT_TO_PTR(crt->cgroup_control_inotify_wd), u);
        if (r < 0)
                return log_unit_error_errno(u, r, "Failed to add control inotify watch descriptor for control group %s to hash map: %m", empty_to_root(crt->cgroup_path));

        return 0;
}

static int unit_watch_cgroup_memory(Unit *u) {
        _cleanup_free_ char *events = NULL;
        int r;

        assert(u);

        /* Watches the "memory.events" attribute of this unit's cgroup for "oom_kill" events. */

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return 0;

        CGroupContext *c = unit_get_cgroup_context(u);
        if (!c)
                return 0;

        /* The "memory.events" attribute is only available if the memory controller is on. Let's hence tie
         * this to memory accounting, in a way watching for OOM kills is a form of memory accounting after
         * all. */
        if (!c->memory_accounting)
                return 0;

        /* Don't watch inner nodes, as the kernel doesn't report oom_kill events recursively currently, and
         * we also don't want to generate a log message for each parent cgroup of a process. */
        if (u->type == UNIT_SLICE)
                return 0;

        if (crt->cgroup_memory_inotify_wd >= 0)
                return 0;

        r = hashmap_ensure_allocated(&u->manager->cgroup_memory_inotify_wd_unit, &trivial_hash_ops);
        if (r < 0)
                return log_oom();

        r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, crt->cgroup_path, "memory.events", &events);
        if (r < 0)
                return log_oom();

        crt->cgroup_memory_inotify_wd = inotify_add_watch(u->manager->cgroup_inotify_fd, events, IN_MODIFY);
        if (crt->cgroup_memory_inotify_wd < 0) {

                if (errno == ENOENT) /* If the directory is already gone we don't need to track it, so this
                                      * is not an error */
                        return 0;

                return log_unit_error_errno(u, errno, "Failed to add memory inotify watch descriptor for control group %s: %m", empty_to_root(crt->cgroup_path));
        }

        r = hashmap_put(u->manager->cgroup_memory_inotify_wd_unit, INT_TO_PTR(crt->cgroup_memory_inotify_wd), u);
        if (r < 0)
                return log_unit_error_errno(u, r, "Failed to add memory inotify watch descriptor for control group %s to hash map: %m", empty_to_root(crt->cgroup_path));

        return 0;
}

static int unit_update_cgroup(
                Unit *u,
                CGroupMask target_mask,
                CGroupMask enable_mask,
                ManagerState state) {

        _cleanup_free_ char *cgroup = NULL, *cgroup_full_path = NULL;
        bool set_path, created;
        int r;

        assert(u);

        if (!UNIT_HAS_CGROUP_CONTEXT(u))
                return 0;

        r = unit_get_cgroup_path_with_fallback(u, &cgroup);
        if (r < 0)
                return log_unit_error_errno(u, r, "Failed to get cgroup path: %m");
        set_path = r == 0;

        /* First, create our own group */
        r = cg_create(cgroup);
        if (r < 0)
                return log_unit_error_errno(u, r, "Failed to create cgroup %s: %m", empty_to_root(cgroup));
        created = r;

        if (set_path) {
                r = unit_set_cgroup_path(u, cgroup);
                if (r == -EEXIST)
                        return log_unit_error_errno(u, r, "Picked control group '%s' as default, but it's in use already.", empty_to_root(cgroup));
                if (r < 0)
                        return log_unit_error_errno(u, r, "Failed to set unit's control group path to '%s': %m", empty_to_root(cgroup));
                assert(r > 0);
        }

        CGroupRuntime *crt = ASSERT_PTR(unit_get_cgroup_runtime(u));

        uint64_t cgroup_id = 0;
        r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, crt->cgroup_path, NULL, &cgroup_full_path);
        if (r == 0) {
                r = cg_path_get_cgroupid(cgroup_full_path, &cgroup_id);
                if (r < 0)
                        log_unit_full_errno(u, ERRNO_IS_NOT_SUPPORTED(r) ? LOG_DEBUG : LOG_WARNING, r,
                                            "Failed to get cgroup ID of cgroup %s, ignoring: %m", cgroup_full_path);
        } else
                log_unit_warning_errno(u, r, "Failed to get full cgroup path on cgroup %s, ignoring: %m", empty_to_root(crt->cgroup_path));

        crt->cgroup_id = cgroup_id;

        /* Start watching it */
        (void) unit_watch_cgroup(u);
        (void) unit_watch_cgroup_memory(u);

        /* For v2 we preserve enabled controllers in delegated units, adjust others, */
        if (created || !unit_cgroup_delegate(u)) {
                CGroupMask result_mask = 0;

                /* Enable all controllers we need */
                r = cg_enable(u->manager->cgroup_supported, enable_mask, crt->cgroup_path, &result_mask);
                if (r < 0)
                        log_unit_warning_errno(u, r, "Failed to enable/disable controllers on cgroup %s, ignoring: %m", empty_to_root(crt->cgroup_path));

                /* Remember what's actually enabled now */
                crt->cgroup_enabled_mask = result_mask;
        }

        /* Keep track that this is now realized */
        crt->cgroup_realized_mask = target_mask;

        /* Set attributes */
        cgroup_context_apply(u, target_mask, state);
        cgroup_xattr_apply(u);

        /* For most units we expect that memory monitoring is set up before the unit is started and we won't
         * touch it after. For PID 1 this is different though, because we couldn't possibly do that given
         * that PID 1 runs before init.scope is even set up. Hence, whenever init.scope is realized, let's
         * try to open the memory pressure interface anew. */
        if (unit_has_name(u, SPECIAL_INIT_SCOPE))
                (void) manager_setup_memory_pressure_event_source(u->manager);

        return 0;
}

static int unit_attach_pid_to_cgroup_via_bus(Unit *u, pid_t pid, const char *suffix_path) {
        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
        char *pp;
        int r;

        assert(u);

        if (MANAGER_IS_SYSTEM(u->manager))
                return -EINVAL;

        if (!u->manager->system_bus)
                return -EIO;

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return -EOWNERDEAD;

        /* Determine this unit's cgroup path relative to our cgroup root */
        pp = path_startswith(crt->cgroup_path, u->manager->cgroup_root);
        if (!pp)
                return -EINVAL;

        pp = strjoina("/", pp, suffix_path);
        path_simplify(pp);

        r = bus_call_method(u->manager->system_bus,
                            bus_systemd_mgr,
                            "AttachProcessesToUnit",
                            &error, NULL,
                            "ssau",
                            NULL /* empty unit name means client's unit, i.e. us */, pp, 1, (uint32_t) pid);
        if (r < 0)
                return log_unit_debug_errno(u, r, "Failed to attach unit process " PID_FMT " via the bus: %s", pid, bus_error_message(&error, r));

        return 0;
}

int unit_attach_pids_to_cgroup(Unit *u, Set *pids, const char *suffix_path) {
        _cleanup_free_ char *joined = NULL;
        const char *p;
        int ret = 0, r;

        assert(u);

        if (!UNIT_HAS_CGROUP_CONTEXT(u))
                return -EINVAL;

        if (set_isempty(pids))
                return 0;

        r = unit_realize_cgroup(u);
        if (r < 0)
                return r;

        CGroupRuntime *crt = ASSERT_PTR(unit_get_cgroup_runtime(u));

        if (isempty(suffix_path))
                p = crt->cgroup_path;
        else {
                joined = path_join(crt->cgroup_path, suffix_path);
                if (!joined)
                        return -ENOMEM;

                p = joined;
        }

        PidRef *pid;
        SET_FOREACH(pid, pids) {

                /* Unfortunately we cannot add pids by pidfd to a cgroup. Hence we have to use PIDs instead,
                 * which of course is racy. Let's shorten the race a bit though, and re-validate the PID
                 * before we use it */
                r = pidref_verify(pid);
                if (r < 0) {
                        log_unit_info_errno(u, r, "PID " PID_FMT " vanished before we could move it to target cgroup '%s', skipping: %m", pid->pid, empty_to_root(p));
                        continue;
                }

                r = cg_attach(p, pid->pid);
                if (r < 0) {
                        bool again = MANAGER_IS_USER(u->manager) && ERRNO_IS_NEG_PRIVILEGE(r);

                        log_unit_full_errno(u, again ? LOG_DEBUG : LOG_INFO,  r,
                                            "Couldn't move process "PID_FMT" to%s requested cgroup '%s': %m",
                                            pid->pid, again ? " directly" : "", empty_to_root(p));

                        if (again) {
                                int z;

                                /* If we are in a user instance, and we can't move the process ourselves due
                                 * to permission problems, let's ask the system instance about it instead.
                                 * Since it's more privileged it might be able to move the process across the
                                 * leaves of a subtree whose top node is not owned by us. */

                                z = unit_attach_pid_to_cgroup_via_bus(u, pid->pid, suffix_path);
                                if (z >= 0)
                                        goto success;

                                log_unit_info_errno(u, z, "Couldn't move process "PID_FMT" to requested cgroup '%s' (directly or via the system bus): %m", pid->pid, empty_to_root(p));
                        }

                        RET_GATHER(ret, r);
                        continue;
                }

        success:
                /* the cgroup is definitely not empty now. in case the unit was in the cgroup empty queue,
                 * drop it from there */
                unit_remove_from_cgroup_empty_queue(u);

                if (ret >= 0)
                        ret++; /* Count successful additions */
        }

        return ret;
}

int unit_remove_subcgroup(Unit *u, const char *suffix_path) {
        int r;

        assert(u);

        if (!UNIT_HAS_CGROUP_CONTEXT(u))
                return -EINVAL;

        if (!unit_cgroup_delegate(u))
                return -ENOMEDIUM;

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return -EOWNERDEAD;

        _cleanup_free_ char *j = NULL;
        bool delete_root;
        const char *d;
        if (empty_or_root(suffix_path)) {
                d = empty_to_root(crt->cgroup_path);
                delete_root = false; /* Don't attempt to delete the main cgroup of this unit */
        } else {
                j = path_join(crt->cgroup_path, suffix_path);
                if (!j)
                        return -ENOMEM;

                d = j;
                delete_root = true;
        }

        log_unit_debug(u, "Removing subcgroup '%s'...", d);

        r = cg_trim(d, delete_root);
        if (r < 0)
                return log_unit_debug_errno(u, r, "Failed to fully %s cgroup '%s': %m", delete_root ? "remove" : "trim", d);

        return 0;
}

static bool unit_has_mask_realized(
                Unit *u,
                CGroupMask target_mask,
                CGroupMask enable_mask) {

        assert(u);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return false;

        /* Returns true if this unit is fully realized. We check four things:
         *
         * 1. Whether the cgroup was created at all
         * 2. Whether the cgroup was created in all the hierarchies we need it to be created in (in case of cgroup v1)
         * 3. Whether the cgroup has all the right controllers enabled (in case of cgroup v2)
         * 4. Whether the invalidation mask is currently zero
         *
         * If you wonder why we mask the target realization and enable mask with CGROUP_MASK_V1/CGROUP_MASK_V2: note
         * that there are three sets of bitmasks: CGROUP_MASK_V1 (for real cgroup v1 controllers), CGROUP_MASK_V2 (for
         * real cgroup v2 controllers) and CGROUP_MASK_BPF (for BPF-based pseudo-controllers). Now, cgroup_realized_mask
         * is only matters for cgroup v1 controllers, and cgroup_enabled_mask only used for cgroup v2, and if they
         * differ in the others, we don't really care. (After all, the cgroup_enabled_mask tracks with controllers are
         * enabled through cgroup.subtree_control, and since the BPF pseudo-controllers don't show up there, they
         * simply don't matter. */

        return crt->cgroup_path &&
                ((crt->cgroup_realized_mask ^ target_mask) & CGROUP_MASK_V1) == 0 &&
                ((crt->cgroup_enabled_mask ^ enable_mask) & CGROUP_MASK_V2) == 0 &&
                crt->cgroup_invalidated_mask == 0;
}

static bool unit_has_mask_disables_realized(
                Unit *u,
                CGroupMask target_mask,
                CGroupMask enable_mask) {

        assert(u);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return true;

        /* Returns true if all controllers which should be disabled are indeed disabled.
         *
         * Unlike unit_has_mask_realized, we don't care what was enabled, only that anything we want to remove is
         * already removed. */

        return !crt->cgroup_path ||
                (FLAGS_SET(crt->cgroup_realized_mask, target_mask & CGROUP_MASK_V1) &&
                 FLAGS_SET(crt->cgroup_enabled_mask, enable_mask & CGROUP_MASK_V2));
}

static bool unit_has_mask_enables_realized(
                Unit *u,
                CGroupMask target_mask,
                CGroupMask enable_mask) {

        assert(u);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return false;

        /* Returns true if all controllers which should be enabled are indeed enabled.
         *
         * Unlike unit_has_mask_realized, we don't care about the controllers that are not present, only that anything
         * we want to add is already added. */

        return crt->cgroup_path &&
                ((crt->cgroup_realized_mask | target_mask) & CGROUP_MASK_V1) == (crt->cgroup_realized_mask & CGROUP_MASK_V1) &&
                ((crt->cgroup_enabled_mask | enable_mask) & CGROUP_MASK_V2) == (crt->cgroup_enabled_mask & CGROUP_MASK_V2);
}

void unit_add_to_cgroup_realize_queue(Unit *u) {
        assert(u);

        if (u->in_cgroup_realize_queue)
                return;

        LIST_APPEND(cgroup_realize_queue, u->manager->cgroup_realize_queue, u);
        u->in_cgroup_realize_queue = true;
}

static void unit_remove_from_cgroup_realize_queue(Unit *u) {
        assert(u);

        if (!u->in_cgroup_realize_queue)
                return;

        LIST_REMOVE(cgroup_realize_queue, u->manager->cgroup_realize_queue, u);
        u->in_cgroup_realize_queue = false;
}

/* Controllers can only be enabled breadth-first, from the root of the
 * hierarchy downwards to the unit in question. */
static int unit_realize_cgroup_now_enable(Unit *u, ManagerState state) {
        CGroupMask target_mask, enable_mask, new_target_mask, new_enable_mask;
        Unit *slice;
        int r;

        assert(u);

        /* First go deal with this unit's parent, or we won't be able to enable
         * any new controllers at this layer. */
        slice = UNIT_GET_SLICE(u);
        if (slice) {
                r = unit_realize_cgroup_now_enable(slice, state);
                if (r < 0)
                        return r;
        }

        target_mask = unit_get_target_mask(u);
        enable_mask = unit_get_enable_mask(u);

        /* We can only enable in this direction, don't try to disable anything.
         */
        if (unit_has_mask_enables_realized(u, target_mask, enable_mask))
                return 0;

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);

        new_target_mask = (crt ? crt->cgroup_realized_mask : 0) | target_mask;
        new_enable_mask = (crt ? crt->cgroup_enabled_mask : 0) | enable_mask;

        return unit_update_cgroup(u, new_target_mask, new_enable_mask, state);
}

/* Controllers can only be disabled depth-first, from the leaves of the
 * hierarchy upwards to the unit in question. */
static int unit_realize_cgroup_now_disable(Unit *u, ManagerState state) {
        Unit *m;

        assert(u);

        if (u->type != UNIT_SLICE)
                return 0;

        UNIT_FOREACH_DEPENDENCY(m, u, UNIT_ATOM_SLICE_OF) {
                CGroupMask target_mask, enable_mask, new_target_mask, new_enable_mask;
                int r;

                CGroupRuntime *rt = unit_get_cgroup_runtime(m);
                if (!rt)
                        continue;

                /* The cgroup for this unit might not actually be fully realised yet, in which case it isn't
                 * holding any controllers open anyway. */
                if (!rt->cgroup_path)
                        continue;

                /* We must disable those below us first in order to release the controller. */
                (void) unit_realize_cgroup_now_disable(m, state);

                target_mask = unit_get_target_mask(m);
                enable_mask = unit_get_enable_mask(m);

                /* We can only disable in this direction, don't try to enable anything. */
                if (unit_has_mask_disables_realized(m, target_mask, enable_mask))
                        continue;

                new_target_mask = rt->cgroup_realized_mask & target_mask;
                new_enable_mask = rt->cgroup_enabled_mask & enable_mask;

                r = unit_update_cgroup(m, new_target_mask, new_enable_mask, state);
                if (r < 0)
                        return r;
        }

        return 0;
}

/* Check if necessary controllers and attributes for a unit are in place.
 *
 * - If so, do nothing.
 * - If not, create paths, move processes over, and set attributes.
 *
 * Controllers can only be *enabled* in a breadth-first way, and *disabled* in
 * a depth-first way. As such the process looks like this:
 *
 * Suppose we have a cgroup hierarchy which looks like this:
 *
 *             root
 *            /    \
 *           /      \
 *          /        \
 *         a          b
 *        / \        / \
 *       /   \      /   \
 *      c     d    e     f
 *     / \   / \  / \   / \
 *     h i   j k  l m   n o
 *
 * 1. We want to realise cgroup "d" now.
 * 2. cgroup "a" has DisableControllers=cpu in the associated unit.
 * 3. cgroup "k" just started requesting the memory controller.
 *
 * To make this work we must do the following in order:
 *
 * 1. Disable CPU controller in k, j
 * 2. Disable CPU controller in d
 * 3. Enable memory controller in root
 * 4. Enable memory controller in a
 * 5. Enable memory controller in d
 * 6. Enable memory controller in k
 *
 * Notice that we need to touch j in one direction, but not the other. We also
 * don't go beyond d when disabling -- it's up to "a" to get realized if it
 * wants to disable further. The basic rules are therefore:
 *
 * - If you're disabling something, you need to realise all of the cgroups from
 *   your recursive descendants to the root. This starts from the leaves.
 * - If you're enabling something, you need to realise from the root cgroup
 *   downwards, but you don't need to iterate your recursive descendants.
 *
 * Returns 0 on success and < 0 on failure. */
static int unit_realize_cgroup_now(Unit *u, ManagerState state) {
        CGroupMask target_mask, enable_mask;
        Unit *slice;
        int r;

        assert(u);

        unit_remove_from_cgroup_realize_queue(u);

        target_mask = unit_get_target_mask(u);
        enable_mask = unit_get_enable_mask(u);

        if (unit_has_mask_realized(u, target_mask, enable_mask))
                return 0;

        /* Disable controllers below us, if there are any */
        r = unit_realize_cgroup_now_disable(u, state);
        if (r < 0)
                return r;

        /* Enable controllers above us, if there are any */
        slice = UNIT_GET_SLICE(u);
        if (slice) {
                r = unit_realize_cgroup_now_enable(slice, state);
                if (r < 0)
                        return r;
        }

        /* Now actually deal with the cgroup we were trying to realise and set attributes */
        r = unit_update_cgroup(u, target_mask, enable_mask, state);
        if (r < 0)
                return r;

        CGroupRuntime *crt = ASSERT_PTR(unit_get_cgroup_runtime(u));

        /* Now, reset the invalidation mask */
        crt->cgroup_invalidated_mask = 0;
        return 0;
}

unsigned manager_dispatch_cgroup_realize_queue(Manager *m) {
        ManagerState state;
        unsigned n = 0;
        Unit *i;
        int r;

        assert(m);

        state = manager_state(m);

        while ((i = m->cgroup_realize_queue)) {
                assert(i->in_cgroup_realize_queue);

                if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(i))) {
                        /* Maybe things changed, and the unit is not actually active anymore? */
                        unit_remove_from_cgroup_realize_queue(i);
                        continue;
                }

                r = unit_realize_cgroup_now(i, state);
                if (r < 0)
                        log_warning_errno(r, "Failed to realize cgroups for queued unit %s, ignoring: %m", i->id);

                n++;
        }

        return n;
}

void unit_add_family_to_cgroup_realize_queue(Unit *u) {
        assert(u);
        assert(u->type == UNIT_SLICE);

        /* Family of a unit for is defined as (immediate) children of the unit and immediate children of all
         * its ancestors.
         *
         * Ideally we would enqueue ancestor path only (bottom up). However, on cgroup-v1 scheduling becomes
         * very weird if two units that own processes reside in the same slice, but one is realized in the
         * "cpu" hierarchy and one is not (for example because one has CPUWeight= set and the other does
         * not), because that means individual processes need to be scheduled against whole cgroups. Let's
         * avoid this asymmetry by always ensuring that siblings of a unit are always realized in their v1
         * controller hierarchies too (if unit requires the controller to be realized).
         *
         * The function must invalidate cgroup_members_mask of all ancestors in order to calculate up to date
         * masks. */

        do {
                CGroupRuntime *crt = unit_get_cgroup_runtime(u);

                /* Children of u likely changed when we're called */
                if (crt)
                        crt->cgroup_members_mask_valid = false;

                Unit *m;
                UNIT_FOREACH_DEPENDENCY(m, u, UNIT_ATOM_SLICE_OF) {

                        /* No point in doing cgroup application for units without active processes. */
                        if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(m)))
                                continue;

                        /* We only enqueue siblings if they were realized once at least, in the main
                         * hierarchy. */
                        crt = unit_get_cgroup_runtime(m);
                        if (!crt || !crt->cgroup_path)
                                continue;

                        /* If the unit doesn't need any new controllers and has current ones
                         * realized, it doesn't need any changes. */
                        if (unit_has_mask_realized(m,
                                                   unit_get_target_mask(m),
                                                   unit_get_enable_mask(m)))
                                continue;

                        unit_add_to_cgroup_realize_queue(m);
                }

                /* Parent comes after children */
                unit_add_to_cgroup_realize_queue(u);

                u = UNIT_GET_SLICE(u);
        } while (u);
}

int unit_realize_cgroup(Unit *u) {
        Unit *slice;

        assert(u);

        if (!UNIT_HAS_CGROUP_CONTEXT(u))
                return 0;

        /* So, here's the deal: when realizing the cgroups for this unit, we need to first create all
         * parents, but there's more actually: for the weight-based controllers we also need to make sure
         * that all our siblings (i.e. units that are in the same slice as we are) have cgroups, too.  On the
         * other hand, when a controller is removed from realized set, it may become unnecessary in siblings
         * and ancestors and they should be (de)realized too.
         *
         * This call will defer work on the siblings and derealized ancestors to the next event loop
         * iteration and synchronously creates the parent cgroups (unit_realize_cgroup_now). */

        slice = UNIT_GET_SLICE(u);
        if (slice)
                unit_add_family_to_cgroup_realize_queue(slice);

        /* And realize this one now (and apply the values) */
        return unit_realize_cgroup_now(u, manager_state(u->manager));
}

void unit_release_cgroup(Unit *u, bool drop_cgroup_runtime) {
        assert(u);

        /* Forgets all cgroup details for this cgroup — but does *not* destroy the cgroup. This is hence OK to call
         * when we close down everything for reexecution, where we really want to leave the cgroup in place. */

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return;

        if (crt->cgroup_path) {
                (void) hashmap_remove(u->manager->cgroup_unit, crt->cgroup_path);
                crt->cgroup_path = mfree(crt->cgroup_path);
        }

        if (crt->cgroup_control_inotify_wd >= 0) {
                if (inotify_rm_watch(u->manager->cgroup_inotify_fd, crt->cgroup_control_inotify_wd) < 0)
                        log_unit_debug_errno(u, errno, "Failed to remove cgroup control inotify watch %i for %s, ignoring: %m", crt->cgroup_control_inotify_wd, u->id);

                (void) hashmap_remove(u->manager->cgroup_control_inotify_wd_unit, INT_TO_PTR(crt->cgroup_control_inotify_wd));
                crt->cgroup_control_inotify_wd = -1;
        }

        if (crt->cgroup_memory_inotify_wd >= 0) {
                if (inotify_rm_watch(u->manager->cgroup_inotify_fd, crt->cgroup_memory_inotify_wd) < 0)
                        log_unit_debug_errno(u, errno, "Failed to remove cgroup memory inotify watch %i for %s, ignoring: %m", crt->cgroup_memory_inotify_wd, u->id);

                (void) hashmap_remove(u->manager->cgroup_memory_inotify_wd_unit, INT_TO_PTR(crt->cgroup_memory_inotify_wd));
                crt->cgroup_memory_inotify_wd = -1;
        }

        if (drop_cgroup_runtime)
                *(CGroupRuntime**) ((uint8_t*) u + UNIT_VTABLE(u)->cgroup_runtime_offset) = cgroup_runtime_free(crt);
}

int unit_cgroup_is_empty(Unit *u) {
        int r;

        assert(u);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return -ENXIO;
        if (!crt->cgroup_path)
                return -EOWNERDEAD;

        r = cg_is_empty(SYSTEMD_CGROUP_CONTROLLER, crt->cgroup_path);
        if (r < 0)
                log_unit_debug_errno(u, r, "Failed to determine whether cgroup %s is empty: %m", empty_to_root(crt->cgroup_path));
        return r;
}

static bool unit_maybe_release_cgroup(Unit *u) {
        int r;

        /* Releases the cgroup only if it is recursively empty.
         * Returns true if the cgroup was released, false otherwise. */

        assert(u);

        /* Don't release the cgroup if there are still processes under it. If we get notified later when all
         * the processes exit (e.g. the processes were in D-state and exited after the unit was marked as
         * failed) we need the cgroup paths to continue to be tracked by the manager so they can be looked up
         * and cleaned up later. */
        r = unit_cgroup_is_empty(u);
        if (r > 0) {
                /* Do not free CGroupRuntime when called from unit_prune_cgroup. Various accounting data
                 * we should keep, especially CPU usage and *_peak ones which would be shown even after
                 * the unit stops. */
                unit_release_cgroup(u, /* drop_cgroup_runtime = */ false);
                return true;
        }

        return false;
}

static int unit_prune_cgroup_via_bus(Unit *u) {
        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
        int r;

        assert(u);
        assert(u->manager);

        if (MANAGER_IS_SYSTEM(u->manager))
                return -EINVAL;

        if (!u->manager->system_bus)
                return -EIO;

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return -EOWNERDEAD;

        /* Determine this unit's cgroup path relative to our cgroup root */
        const char *pp = path_startswith_full(
                        crt->cgroup_path,
                        u->manager->cgroup_root,
                        PATH_STARTSWITH_RETURN_LEADING_SLASH|PATH_STARTSWITH_REFUSE_DOT_DOT);
        if (!pp)
                return -EINVAL;

        r = bus_call_method(u->manager->system_bus,
                            bus_systemd_mgr,
                            "RemoveSubgroupFromUnit",
                            &error, NULL,
                            "sst",
                            NULL /* empty unit name means client's unit, i.e. us */,
                            pp,
                            (uint64_t) 0);
        if (r < 0)
                return log_unit_debug_errno(u, r, "Failed to trim cgroup via the bus: %s", bus_error_message(&error, r));

        return 0;
}

void unit_prune_cgroup(Unit *u) {
        bool is_root_slice;
        int r;

        assert(u);

        /* Removes the cgroup, if empty and possible, and stops watching it. */
        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return;

        /* Cache the last resource usage values before we destroy the cgroup */
        (void) unit_get_cpu_usage(u, /* ret = */ NULL);

        for (CGroupMemoryAccountingMetric metric = 0; metric <= _CGROUP_MEMORY_ACCOUNTING_METRIC_CACHED_LAST; metric++)
                (void) unit_get_memory_accounting(u, metric, /* ret = */ NULL);

        /* All IO metrics are read at once from the underlying cgroup, so issue just a single call */
        (void) unit_get_io_accounting(u, _CGROUP_IO_ACCOUNTING_METRIC_INVALID, /* ret = */ NULL);

        /* We do not cache IP metrics here because the firewall objects are not freed with cgroups */

#if BPF_FRAMEWORK
        (void) bpf_restrict_fs_cleanup(u); /* Remove cgroup from the global LSM BPF map */
#endif

        unit_modify_nft_set(u, /* add = */ false);

        is_root_slice = unit_has_name(u, SPECIAL_ROOT_SLICE);

        r = cg_trim(crt->cgroup_path, !is_root_slice);
        if (r < 0) {
                int k = unit_prune_cgroup_via_bus(u);

                if (k >= 0)
                        log_unit_debug_errno(u, r, "Failed to destroy cgroup %s on our own (%m), but worked when talking to PID 1.", empty_to_root(crt->cgroup_path));
                else {
                        /* One reason we could have failed here is, that the cgroup still contains a process.
                         * However, if the cgroup becomes removable at a later time, it might be removed when
                         * the containing slice is stopped. So even if we failed now, this unit shouldn't
                         * assume that the cgroup is still realized the next time it is started. Do not
                         * return early on error, continue cleanup. */
                        log_unit_full_errno(u, r == -EBUSY ? LOG_DEBUG : LOG_WARNING, r,
                                            "Failed to destroy cgroup %s, ignoring: %m", empty_to_root(crt->cgroup_path));
                }
        }

        if (is_root_slice)
                return;

        if (!unit_maybe_release_cgroup(u)) /* Returns true if the cgroup was released */
                return;

        assert(crt == unit_get_cgroup_runtime(u));
        assert(!crt->cgroup_path);

        crt->cgroup_realized_mask = 0;
        crt->cgroup_enabled_mask = 0;

        crt->bpf_device_control_installed = bpf_program_free(crt->bpf_device_control_installed);
}

int unit_search_main_pid(Unit *u, PidRef *ret) {
        _cleanup_(pidref_done) PidRef pidref = PIDREF_NULL;
        _cleanup_fclose_ FILE *f = NULL;
        int r;

        assert(u);
        assert(ret);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return -ENXIO;

        r = cg_enumerate_processes(SYSTEMD_CGROUP_CONTROLLER, crt->cgroup_path, &f);
        if (r < 0)
                return r;

        for (;;) {
                _cleanup_(pidref_done) PidRef npidref = PIDREF_NULL;

                /* cg_read_pidref() will return an error on unmapped PIDs.
                 * We can't reasonably deal with units that contain those. */
                r = cg_read_pidref(f, &npidref, CGROUP_DONT_SKIP_UNMAPPED);
                if (r < 0)
                        return r;
                if (r == 0)
                        break;

                if (pidref_equal(&pidref, &npidref)) /* seen already, cgroupfs reports duplicates! */
                        continue;

                if (pidref_is_my_child(&npidref) <= 0) /* ignore processes further down the tree */
                        continue;

                if (pidref_is_set(&pidref) != 0)
                        /* Dang, there's more than one daemonized PID in this group, so we don't know what
                         * process is the main process. */
                        return -ENODATA;

                pidref = TAKE_PIDREF(npidref);
        }

        if (!pidref_is_set(&pidref))
                return -ENODATA;

        *ret = TAKE_PIDREF(pidref);
        return 0;
}

static int on_cgroup_empty_event(sd_event_source *s, void *userdata) {
        Manager *m = ASSERT_PTR(userdata);
        Unit *u;
        int r;

        assert(s);

        u = m->cgroup_empty_queue;
        if (!u)
                return 0;

        assert(u->in_cgroup_empty_queue);
        u->in_cgroup_empty_queue = false;
        LIST_REMOVE(cgroup_empty_queue, m->cgroup_empty_queue, u);

        if (m->cgroup_empty_queue) {
                /* More stuff queued, let's make sure we remain enabled */
                r = sd_event_source_set_enabled(s, SD_EVENT_ONESHOT);
                if (r < 0)
                        log_debug_errno(r, "Failed to reenable cgroup empty event source, ignoring: %m");
        }

        /* Update state based on OOM kills before we notify about cgroup empty event */
        (void) unit_check_oom(u);
        (void) unit_check_oomd_kill(u);

        unit_add_to_gc_queue(u);

        if (UNIT_IS_INACTIVE_OR_FAILED(unit_active_state(u)))
                unit_prune_cgroup(u);
        else if (UNIT_VTABLE(u)->notify_cgroup_empty)
                UNIT_VTABLE(u)->notify_cgroup_empty(u);

        return 0;
}

static void unit_add_to_cgroup_empty_queue(Unit *u) {
        int r;

        assert(u);

        /* Note that cgroup empty events are dispatched in a separate queue with a lower priority than
         * the SIGCHLD handler, so that we always use SIGCHLD if we can get it first, and only use
         * the cgroup empty notifications if there's no SIGCHLD pending (which might happen if the cgroup
         * doesn't contain processes that are our own child, which is typically the case for scope units). */

        if (u->in_cgroup_empty_queue)
                return;

        LIST_PREPEND(cgroup_empty_queue, u->manager->cgroup_empty_queue, u);
        u->in_cgroup_empty_queue = true;

        /* Trigger the defer event */
        r = sd_event_source_set_enabled(u->manager->cgroup_empty_event_source, SD_EVENT_ONESHOT);
        if (r < 0)
                log_debug_errno(r, "Failed to enable cgroup empty event source: %m");
}

static void unit_remove_from_cgroup_empty_queue(Unit *u) {
        assert(u);

        if (!u->in_cgroup_empty_queue)
                return;

        LIST_REMOVE(cgroup_empty_queue, u->manager->cgroup_empty_queue, u);
        u->in_cgroup_empty_queue = false;
}

int unit_check_oomd_kill(Unit *u) {
        _cleanup_free_ char *value = NULL;
        bool increased;
        uint64_t n = 0;
        int r;

        assert(u);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return 0;

        r = cg_get_xattr(crt->cgroup_path, "user.oomd_ooms", &value, /* ret_size= */ NULL);
        if (r < 0 && !ERRNO_IS_XATTR_ABSENT(r))
                return r;

        if (!isempty(value)) {
                 r = safe_atou64(value, &n);
                 if (r < 0)
                         return r;
        }

        increased = n > crt->managed_oom_kill_last;
        crt->managed_oom_kill_last = n;

        if (!increased)
                return 0;

        n = 0;
        value = mfree(value);
        r = cg_get_xattr(crt->cgroup_path, "user.oomd_kill", &value, /* ret_size= */ NULL);
        if (r >= 0 && !isempty(value))
                (void) safe_atou64(value, &n);

        if (n > 0)
                log_unit_struct(u, LOG_NOTICE,
                                LOG_MESSAGE_ID(SD_MESSAGE_UNIT_OOMD_KILL_STR),
                                LOG_UNIT_INVOCATION_ID(u),
                                LOG_UNIT_MESSAGE(u, "systemd-oomd killed %"PRIu64" process(es) in this unit.", n),
                                LOG_ITEM("N_PROCESSES=%" PRIu64, n));
        else
                log_unit_struct(u, LOG_NOTICE,
                                LOG_MESSAGE_ID(SD_MESSAGE_UNIT_OOMD_KILL_STR),
                                LOG_UNIT_INVOCATION_ID(u),
                                LOG_UNIT_MESSAGE(u, "systemd-oomd killed some process(es) in this unit."));

        unit_notify_cgroup_oom(u, /* managed_oom= */ true);

        return 1;
}

int unit_check_oom(Unit *u) {
        _cleanup_free_ char *oom_kill = NULL;
        bool increased;
        uint64_t c;
        int r;

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return 0;

        CGroupContext *ctx = unit_get_cgroup_context(u);
        if (!ctx)
                return 0;

        /* If memory.oom.group=1, then look up the oom_group_kill field, which reports how many times the
         * kernel killed every process recursively in this cgroup and its descendants, similar to
         * systemd-oomd. Because the memory.events.local file was only introduced in kernel 5.12, we fall
         * back to reading oom_kill if we can't find the file or field. */

        if (ctx->memory_oom_group) {
                r = cg_get_keyed_attribute(
                        "memory",
                        crt->cgroup_path,
                        "memory.events.local",
                        STRV_MAKE("oom_group_kill"),
                        &oom_kill);
                if (r < 0 && !IN_SET(r, -ENOENT, -ENXIO))
                        return log_unit_debug_errno(u, r, "Failed to read oom_group_kill field of memory.events.local cgroup attribute, ignoring: %m");
        }

        if (isempty(oom_kill)) {
                r = cg_get_keyed_attribute(
                        "memory",
                        crt->cgroup_path,
                        "memory.events",
                        STRV_MAKE("oom_kill"),
                        &oom_kill);
                if (r < 0 && !IN_SET(r, -ENOENT, -ENXIO))
                        return log_unit_debug_errno(u, r, "Failed to read oom_kill field of memory.events cgroup attribute: %m");
        }

        if (!oom_kill)
                c = 0;
        else {
                r = safe_atou64(oom_kill, &c);
                if (r < 0)
                        return log_unit_debug_errno(u, r, "Failed to parse memory.events cgroup oom field: %m");
        }

        increased = c > crt->oom_kill_last;
        crt->oom_kill_last = c;

        if (!increased)
                return 0;

        log_unit_struct(u, LOG_NOTICE,
                        LOG_MESSAGE_ID(SD_MESSAGE_UNIT_OUT_OF_MEMORY_STR),
                        LOG_UNIT_INVOCATION_ID(u),
                        LOG_UNIT_MESSAGE(u, "The kernel OOM killer killed some processes in this unit."));

        unit_notify_cgroup_oom(u, /* managed_oom= */ false);

        return 1;
}

static int on_cgroup_oom_event(sd_event_source *s, void *userdata) {
        Manager *m = ASSERT_PTR(userdata);
        Unit *u;
        int r;

        assert(s);

        u = m->cgroup_oom_queue;
        if (!u)
                return 0;

        assert(u->in_cgroup_oom_queue);
        u->in_cgroup_oom_queue = false;
        LIST_REMOVE(cgroup_oom_queue, m->cgroup_oom_queue, u);

        if (m->cgroup_oom_queue) {
                /* More stuff queued, let's make sure we remain enabled */
                r = sd_event_source_set_enabled(s, SD_EVENT_ONESHOT);
                if (r < 0)
                        log_debug_errno(r, "Failed to reenable cgroup oom event source, ignoring: %m");
        }

        (void) unit_check_oom(u);
        unit_add_to_gc_queue(u);

        return 0;
}

static void unit_add_to_cgroup_oom_queue(Unit *u) {
        int r;

        assert(u);

        if (u->in_cgroup_oom_queue)
                return;

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return;

        LIST_PREPEND(cgroup_oom_queue, u->manager->cgroup_oom_queue, u);
        u->in_cgroup_oom_queue = true;

        /* Trigger the defer event */
        if (!u->manager->cgroup_oom_event_source) {
                _cleanup_(sd_event_source_unrefp) sd_event_source *s = NULL;

                r = sd_event_add_defer(u->manager->event, &s, on_cgroup_oom_event, u->manager);
                if (r < 0) {
                        log_error_errno(r, "Failed to create cgroup oom event source: %m");
                        return;
                }

                r = sd_event_source_set_priority(s, EVENT_PRIORITY_CGROUP_OOM);
                if (r < 0) {
                        log_error_errno(r, "Failed to set priority of cgroup oom event source: %m");
                        return;
                }

                (void) sd_event_source_set_description(s, "cgroup-oom");
                u->manager->cgroup_oom_event_source = TAKE_PTR(s);
        }

        r = sd_event_source_set_enabled(u->manager->cgroup_oom_event_source, SD_EVENT_ONESHOT);
        if (r < 0)
                log_error_errno(r, "Failed to enable cgroup oom event source: %m");
}

static int unit_check_cgroup_events(Unit *u) {
        char *values[2] = {};
        int r;

        assert(u);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return 0;

        r = cg_get_keyed_attribute(
                        SYSTEMD_CGROUP_CONTROLLER,
                        crt->cgroup_path,
                        "cgroup.events",
                        STRV_MAKE("populated", "frozen"),
                        values);
        if (r < 0)
                return r;

        /* The cgroup.events notifications can be merged together so act as we saw the given state for the
         * first time. The functions we call to handle given state are idempotent, which makes them
         * effectively remember the previous state. */
        if (streq(values[0], "1"))
                unit_remove_from_cgroup_empty_queue(u);
        else
                unit_add_to_cgroup_empty_queue(u);

        /* Disregard freezer state changes due to operations not initiated by us.
         * See: https://github.com/systemd/systemd/pull/13512/files#r416469963 and
         *      https://github.com/systemd/systemd/pull/13512#issuecomment-573007207 */
        if (IN_SET(u->freezer_state, FREEZER_FREEZING, FREEZER_FREEZING_BY_PARENT, FREEZER_THAWING))
                unit_freezer_complete(u, streq(values[1], "0") ? FREEZER_RUNNING : FREEZER_FROZEN);

        free_many_charp(values, ELEMENTSOF(values));
        return 0;
}

static int on_cgroup_inotify_event(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
        Manager *m = ASSERT_PTR(userdata);

        assert(s);
        assert(fd >= 0);

        for (;;) {
                union inotify_event_buffer buffer;
                ssize_t l;

                l = read(fd, &buffer, sizeof(buffer));
                if (l < 0) {
                        if (ERRNO_IS_TRANSIENT(errno))
                                return 0;

                        return log_error_errno(errno, "Failed to read control group inotify events: %m");
                }

                FOREACH_INOTIFY_EVENT_WARN(e, buffer, l) {
                        Unit *u;

                        if (e->wd < 0)
                                /* Queue overflow has no watch descriptor */
                                continue;

                        if (e->mask & IN_IGNORED)
                                /* The watch was just removed */
                                continue;

                        /* Note that inotify might deliver events for a watch even after it was removed,
                         * because it was queued before the removal. Let's ignore this here safely. */

                        u = hashmap_get(m->cgroup_control_inotify_wd_unit, INT_TO_PTR(e->wd));
                        if (u)
                                unit_check_cgroup_events(u);

                        u = hashmap_get(m->cgroup_memory_inotify_wd_unit, INT_TO_PTR(e->wd));
                        if (u)
                                unit_add_to_cgroup_oom_queue(u);
                }
        }
}

static int cg_bpf_mask_supported(CGroupMask *ret) {
        CGroupMask mask = 0;
        int r;

        /* BPF-based firewall, device access control, and pinned foreign prog */
        if (bpf_program_supported() > 0)
                mask |= CGROUP_MASK_BPF_FIREWALL |
                        CGROUP_MASK_BPF_DEVICES |
                        CGROUP_MASK_BPF_FOREIGN;

        /* BPF-based bind{4|6} hooks */
        r = bpf_socket_bind_supported();
        if (r < 0)
                return r;
        if (r > 0)
                mask |= CGROUP_MASK_BPF_SOCKET_BIND;

        /* BPF-based cgroup_skb/{egress|ingress} hooks */
        r = bpf_restrict_ifaces_supported();
        if (r < 0)
                return r;
        if (r > 0)
                mask |= CGROUP_MASK_BPF_RESTRICT_NETWORK_INTERFACES;

        *ret = mask;
        return 0;
}

int manager_setup_cgroup(Manager *m) {
        int r;

        assert(m);

        /* 1. Determine hierarchy */
        m->cgroup_root = mfree(m->cgroup_root);
        r = cg_pid_get_path(SYSTEMD_CGROUP_CONTROLLER, 0, &m->cgroup_root);
        if (r < 0)
                return log_error_errno(r, "Cannot determine cgroup we are running in: %m");

        /* Chop off the init scope, if we are already located in it */
        char *e = endswith(m->cgroup_root, "/" SPECIAL_INIT_SCOPE);
        if (e)
                *e = 0;

        /* And make sure to store away the root value without trailing slash, even for the root dir, so that we can
         * easily prepend it everywhere. */
        delete_trailing_chars(m->cgroup_root, "/");

        /* 2. Pin the cgroupfs mount, so that it cannot be unmounted */
        safe_close(m->pin_cgroupfs_fd);
        m->pin_cgroupfs_fd = open("/sys/fs/cgroup", O_PATH|O_CLOEXEC|O_DIRECTORY);
        if (m->pin_cgroupfs_fd < 0)
                return log_error_errno(errno, "Failed to pin cgroup hierarchy: %m");

        /* 3. Allocate cgroup empty defer event source */
        m->cgroup_empty_event_source = sd_event_source_disable_unref(m->cgroup_empty_event_source);
        r = sd_event_add_defer(m->event, &m->cgroup_empty_event_source, on_cgroup_empty_event, m);
        if (r < 0)
                return log_error_errno(r, "Failed to create cgroup empty event source: %m");

        /* Schedule cgroup empty checks early, but after having processed service notification messages or
         * SIGCHLD signals, so that a cgroup running empty is always just the last safety net of
         * notification, and we collected the metadata the notification and SIGCHLD stuff offers first. */
        r = sd_event_source_set_priority(m->cgroup_empty_event_source, EVENT_PRIORITY_CGROUP_EMPTY);
        if (r < 0)
                return log_error_errno(r, "Failed to set priority of cgroup empty event source: %m");

        r = sd_event_source_set_enabled(m->cgroup_empty_event_source, SD_EVENT_OFF);
        if (r < 0)
                return log_error_errno(r, "Failed to disable cgroup empty event source: %m");

        (void) sd_event_source_set_description(m->cgroup_empty_event_source, "cgroup-empty");

        /* 4. Install cgroup empty event notifier inotify object */
        m->cgroup_inotify_event_source = sd_event_source_disable_unref(m->cgroup_inotify_event_source);
        safe_close(m->cgroup_inotify_fd);

        m->cgroup_inotify_fd = inotify_init1(IN_NONBLOCK|IN_CLOEXEC);
        if (m->cgroup_inotify_fd < 0)
                return log_error_errno(errno, "Failed to create control group inotify object: %m");

        r = sd_event_add_io(m->event, &m->cgroup_inotify_event_source, m->cgroup_inotify_fd, EPOLLIN, on_cgroup_inotify_event, m);
        if (r < 0)
                return log_error_errno(r, "Failed to watch control group inotify object: %m");

        /* Process cgroup empty notifications early. Note that when this event is dispatched it'll
         * just add the unit to a cgroup empty queue, hence let's run earlier than that. Also see
         * handling of cgroup agent notifications, for the classic cgroup hierarchy support. */
        r = sd_event_source_set_priority(m->cgroup_inotify_event_source, EVENT_PRIORITY_CGROUP_INOTIFY);
        if (r < 0)
                return log_error_errno(r, "Failed to set priority of inotify event source: %m");

        (void) sd_event_source_set_description(m->cgroup_inotify_event_source, "cgroup-inotify");

        /* 5. Make sure we are in the special "init.scope" unit in the root slice. */
        const char *scope_path = strjoina(m->cgroup_root, "/" SPECIAL_INIT_SCOPE);
        r = cg_create_and_attach(scope_path, /* pid = */ 0);
        if (r >= 0) {
                /* Also, move all other userspace processes remaining in the root cgroup into that scope. */
                r = cg_migrate(m->cgroup_root, scope_path, 0);
                if (r < 0)
                        log_warning_errno(r, "Couldn't move remaining userspace processes, ignoring: %m");

        } else if (!MANAGER_IS_TEST_RUN(m))
                return log_error_errno(r, "Failed to create %s control group: %m", scope_path);

        /* 6. Figure out which controllers are supported */
        r = cg_mask_supported_subtree(m->cgroup_root, &m->cgroup_supported);
        if (r < 0)
                return log_error_errno(r, "Failed to determine supported controllers: %m");

        /* 7. Figure out which bpf-based pseudo-controllers are supported */
        CGroupMask mask;
        r = cg_bpf_mask_supported(&mask);
        if (r < 0)
                return log_error_errno(r, "Failed to determine supported bpf-based pseudo-controllers: %m");
        m->cgroup_supported |= mask;

        /* 8. Log which controllers are supported */
        for (CGroupController c = 0; c < _CGROUP_CONTROLLER_MAX; c++)
                log_debug("Controller '%s' supported: %s", cgroup_controller_to_string(c),
                          yes_no(m->cgroup_supported & CGROUP_CONTROLLER_TO_MASK(c)));

        return 0;
}

void manager_shutdown_cgroup(Manager *m, bool delete) {
        assert(m);

        /* We can't really delete the group, since we are in it. But
         * let's trim it. */
        if (delete && m->cgroup_root && !FLAGS_SET(m->test_run_flags, MANAGER_TEST_RUN_MINIMAL))
                (void) cg_trim(m->cgroup_root, false);

        m->cgroup_empty_event_source = sd_event_source_disable_unref(m->cgroup_empty_event_source);

        m->cgroup_control_inotify_wd_unit = hashmap_free(m->cgroup_control_inotify_wd_unit);
        m->cgroup_memory_inotify_wd_unit = hashmap_free(m->cgroup_memory_inotify_wd_unit);

        m->cgroup_inotify_event_source = sd_event_source_disable_unref(m->cgroup_inotify_event_source);
        m->cgroup_inotify_fd = safe_close(m->cgroup_inotify_fd);

        m->pin_cgroupfs_fd = safe_close(m->pin_cgroupfs_fd);

        m->cgroup_root = mfree(m->cgroup_root);
}

Unit* manager_get_unit_by_cgroup(Manager *m, const char *cgroup) {
        char *p;
        Unit *u;

        assert(m);
        assert(cgroup);

        u = hashmap_get(m->cgroup_unit, cgroup);
        if (u)
                return u;

        p = strdupa_safe(cgroup);
        for (;;) {
                char *e;

                e = strrchr(p, '/');
                if (!e || e == p)
                        return NULL; /* reached cgroup root? return NULL and possibly fall back to manager_get_unit_by_pidref_watching() */

                *e = 0;

                u = hashmap_get(m->cgroup_unit, p);
                if (u)
                        return u;
        }
}

Unit* manager_get_unit_by_pidref_cgroup(Manager *m, const PidRef *pid) {
        _cleanup_free_ char *cgroup = NULL;

        assert(m);

        if (cg_pidref_get_path(SYSTEMD_CGROUP_CONTROLLER, pid, &cgroup) < 0)
                return NULL;

        return manager_get_unit_by_cgroup(m, cgroup);
}

Unit* manager_get_unit_by_pidref_watching(Manager *m, const PidRef *pid) {
        Unit *u, **array;

        assert(m);

        if (!pidref_is_set(pid))
                return NULL;

        u = hashmap_get(m->watch_pids, pid);
        if (u)
                return u;

        array = hashmap_get(m->watch_pids_more, pid);
        if (array)
                return array[0];

        return NULL;
}

Unit* manager_get_unit_by_pidref(Manager *m, PidRef *pid) {
        Unit *u;

        assert(m);

        /* Note that a process might be owned by multiple units, we return only one here, which is good
         * enough for most cases, though not strictly correct. We prefer the one reported by cgroup
         * membership, as that's the most relevant one as children of the process will be assigned to that
         * one, too, before all else. */

        if (!pidref_is_set(pid))
                return NULL;

        if (pidref_is_self(pid))
                return hashmap_get(m->units, SPECIAL_INIT_SCOPE);
        if (pid->pid == 1)
                return NULL;

        u = manager_get_unit_by_pidref_cgroup(m, pid);
        if (u)
                return u;

        u = manager_get_unit_by_pidref_watching(m, pid);
        if (u)
                return u;

        return NULL;
}

int unit_get_memory_available(Unit *u, uint64_t *ret) {
        uint64_t available = UINT64_MAX, current = 0;

        assert(u);
        assert(ret);

        /* If data from cgroups can be accessed, try to find out how much more memory a unit can
         * claim before hitting the configured cgroup limits (if any). Consider both MemoryHigh
         * and MemoryMax, and also any slice the unit might be nested below. */

        do {
                uint64_t unit_available, unit_limit = UINT64_MAX;
                CGroupContext *unit_context;

                /* No point in continuing if we can't go any lower */
                if (available == 0)
                        break;

                unit_context = unit_get_cgroup_context(u);
                if (!unit_context)
                        return -ENODATA;

                (void) unit_get_memory_accounting(u, CGROUP_MEMORY_CURRENT, &current);
                /* in case of error, previous current propagates as lower bound */

                if (unit_has_name(u, SPECIAL_ROOT_SLICE))
                        unit_limit = physical_memory();
                else if (unit_context->memory_max == UINT64_MAX && unit_context->memory_high == UINT64_MAX)
                        continue;
                unit_limit = MIN3(unit_limit, unit_context->memory_max, unit_context->memory_high);

                unit_available = LESS_BY(unit_limit, current);
                available = MIN(unit_available, available);
        } while ((u = UNIT_GET_SLICE(u)));

        *ret = available;

        return 0;
}

int unit_get_memory_accounting(Unit *u, CGroupMemoryAccountingMetric metric, uint64_t *ret) {

        static const char* const attributes_table[_CGROUP_MEMORY_ACCOUNTING_METRIC_MAX] = {
                [CGROUP_MEMORY_CURRENT]       = "memory.current",
                [CGROUP_MEMORY_PEAK]          = "memory.peak",
                [CGROUP_MEMORY_SWAP_CURRENT]  = "memory.swap.current",
                [CGROUP_MEMORY_SWAP_PEAK]     = "memory.swap.peak",
                [CGROUP_MEMORY_ZSWAP_CURRENT] = "memory.zswap.current",
        };

        uint64_t bytes;
        bool updated = false;
        int r;

        assert(u);
        assert(metric >= 0);
        assert(metric < _CGROUP_MEMORY_ACCOUNTING_METRIC_MAX);

        if (!UNIT_CGROUP_BOOL(u, memory_accounting))
                return -ENODATA;

        /* The root cgroup doesn't expose this information. */
        if (unit_has_host_root_cgroup(u)) {
                /* System-wide memory usage can be acquired from /proc/ */
                if (metric == CGROUP_MEMORY_CURRENT)
                        return procfs_memory_get_used(ret);

                return -ENODATA;
        }

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return -ENODATA;
        if (!crt->cgroup_path)
                /* If the cgroup is already gone, we try to find the last cached value. */
                goto finish;

        if (!FLAGS_SET(crt->cgroup_realized_mask, CGROUP_MASK_MEMORY))
                return -ENODATA;

        r = cg_get_attribute_as_uint64("memory", crt->cgroup_path, attributes_table[metric], &bytes);
        if (r < 0 && r != -ENODATA)
                return r;
        updated = r >= 0;

finish:
        if (metric <= _CGROUP_MEMORY_ACCOUNTING_METRIC_CACHED_LAST) {
                uint64_t *last = &crt->memory_accounting_last[metric];

                if (updated)
                        *last = bytes;
                else if (*last != UINT64_MAX)
                        bytes = *last;
                else
                        return -ENODATA;

        } else if (!updated)
                return -ENODATA;

        if (ret)
                *ret = bytes;

        return 0;
}

int unit_get_tasks_current(Unit *u, uint64_t *ret) {
        assert(u);
        assert(ret);

        if (!UNIT_CGROUP_BOOL(u, tasks_accounting))
                return -ENODATA;

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return -ENODATA;

        /* The root cgroup doesn't expose this information, let's get it from /proc instead */
        if (unit_has_host_root_cgroup(u))
                return procfs_tasks_get_current(ret);

        if ((crt->cgroup_realized_mask & CGROUP_MASK_PIDS) == 0)
                return -ENODATA;

        return cg_get_attribute_as_uint64("pids", crt->cgroup_path, "pids.current", ret);
}

static int unit_get_cpu_usage_raw(const Unit *u, const CGroupRuntime *crt, nsec_t *ret) {
        int r;

        assert(u);
        assert(crt);
        assert(ret);

        if (!crt->cgroup_path)
                return -ENODATA;

        /* The root cgroup doesn't expose this information, let's get it from /proc instead */
        if (unit_has_host_root_cgroup(u))
                return procfs_cpu_get_usage(ret);

        _cleanup_free_ char *val = NULL;
        uint64_t us;

        r = cg_get_keyed_attribute("cpu", crt->cgroup_path, "cpu.stat", STRV_MAKE("usage_usec"), &val);
        if (r < 0)
                return r;

        r = safe_atou64(val, &us);
        if (r < 0)
                return r;

        *ret = us * NSEC_PER_USEC;

        return 0;
}

int unit_get_cpu_usage(Unit *u, nsec_t *ret) {
        nsec_t ns;
        int r;

        assert(u);

        /* Retrieve the current CPU usage counter. This will subtract the CPU counter taken when the unit was
         * started. If the cgroup has been removed already, returns the last cached value. To cache the value, simply
         * call this function with a NULL return value. */

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return -ENODATA;

        r = unit_get_cpu_usage_raw(u, crt, &ns);
        if (r == -ENODATA && crt->cpu_usage_last != NSEC_INFINITY) {
                /* If we can't get the CPU usage anymore (because the cgroup was already removed, for example), use our
                 * cached value. */

                if (ret)
                        *ret = crt->cpu_usage_last;
                return 0;
        }
        if (r < 0)
                return r;

        if (ns > crt->cpu_usage_base)
                ns -= crt->cpu_usage_base;
        else
                ns = 0;

        crt->cpu_usage_last = ns;
        if (ret)
                *ret = ns;

        return 0;
}

int unit_get_ip_accounting(
                Unit *u,
                CGroupIPAccountingMetric metric,
                uint64_t *ret) {

        uint64_t value;
        int fd, r;

        assert(u);
        assert(metric >= 0);
        assert(metric < _CGROUP_IP_ACCOUNTING_METRIC_MAX);
        assert(ret);

        if (!UNIT_CGROUP_BOOL(u, ip_accounting))
                return -ENODATA;

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return -ENODATA;

        fd = IN_SET(metric, CGROUP_IP_INGRESS_BYTES, CGROUP_IP_INGRESS_PACKETS) ?
                crt->ip_accounting_ingress_map_fd :
                crt->ip_accounting_egress_map_fd;
        if (fd < 0)
                return -ENODATA;

        if (IN_SET(metric, CGROUP_IP_INGRESS_BYTES, CGROUP_IP_EGRESS_BYTES))
                r = bpf_firewall_read_accounting(fd, &value, NULL);
        else
                r = bpf_firewall_read_accounting(fd, NULL, &value);
        if (r < 0)
                return r;

        /* Add in additional metrics from a previous runtime. Note that when reexecing/reloading the daemon we compile
         * all BPF programs and maps anew, but serialize the old counters. When deserializing we store them in the
         * ip_accounting_extra[] field, and add them in here transparently. */

        *ret = value + crt->ip_accounting_extra[metric];

        return r;
}

static uint64_t unit_get_effective_limit_one(Unit *u, CGroupLimitType type) {
        CGroupContext *cc;

        assert(u);
        assert(UNIT_HAS_CGROUP_CONTEXT(u));

        if (unit_has_name(u, SPECIAL_ROOT_SLICE))
                switch (type) {
                        case CGROUP_LIMIT_MEMORY_MAX:
                        case CGROUP_LIMIT_MEMORY_HIGH:
                                return physical_memory();
                        case CGROUP_LIMIT_TASKS_MAX:
                                return system_tasks_max();
                        default:
                                assert_not_reached();
                }

        cc = ASSERT_PTR(unit_get_cgroup_context(u));
        switch (type) {
                case CGROUP_LIMIT_MEMORY_MAX:
                        return cc->memory_max;
                case CGROUP_LIMIT_MEMORY_HIGH:
                        return cc->memory_high;
                case CGROUP_LIMIT_TASKS_MAX:
                        return cgroup_tasks_max_resolve(&cc->tasks_max);
                default:
                        assert_not_reached();
        }
}

int unit_get_effective_limit(Unit *u, CGroupLimitType type, uint64_t *ret) {
        uint64_t infimum;

        assert(u);
        assert(ret);
        assert(type >= 0);
        assert(type < _CGROUP_LIMIT_TYPE_MAX);

        if (!UNIT_HAS_CGROUP_CONTEXT(u))
                return -EINVAL;

        infimum = unit_get_effective_limit_one(u, type);
        for (Unit *slice = UNIT_GET_SLICE(u); slice; slice = UNIT_GET_SLICE(slice))
                infimum = MIN(infimum, unit_get_effective_limit_one(slice, type));

        *ret = infimum;
        return 0;
}

static int unit_get_io_accounting_raw(
                const Unit *u,
                const CGroupRuntime *crt,
                uint64_t ret[static _CGROUP_IO_ACCOUNTING_METRIC_MAX]) {

        static const char* const field_names[_CGROUP_IO_ACCOUNTING_METRIC_MAX] = {
                [CGROUP_IO_READ_BYTES]       = "rbytes=",
                [CGROUP_IO_WRITE_BYTES]      = "wbytes=",
                [CGROUP_IO_READ_OPERATIONS]  = "rios=",
                [CGROUP_IO_WRITE_OPERATIONS] = "wios=",
        };

        uint64_t acc[_CGROUP_IO_ACCOUNTING_METRIC_MAX] = {};
        _cleanup_free_ char *path = NULL;
        _cleanup_fclose_ FILE *f = NULL;
        int r;

        assert(u);
        assert(crt);

        if (!crt->cgroup_path)
                return -ENODATA;

        if (unit_has_host_root_cgroup(u))
                return -ENODATA; /* TODO: return useful data for the top-level cgroup */

        if (!FLAGS_SET(crt->cgroup_realized_mask, CGROUP_MASK_IO))
                return -ENODATA;

        r = cg_get_path("io", crt->cgroup_path, "io.stat", &path);
        if (r < 0)
                return r;

        f = fopen(path, "re");
        if (!f)
                return -errno;

        for (;;) {
                _cleanup_free_ char *line = NULL;
                const char *p;

                r = read_line(f, LONG_LINE_MAX, &line);
                if (r < 0)
                        return r;
                if (r == 0)
                        break;

                p = line;
                p += strcspn(p, WHITESPACE); /* Skip over device major/minor */
                p += strspn(p, WHITESPACE);  /* Skip over following whitespace */

                for (;;) {
                        _cleanup_free_ char *word = NULL;

                        r = extract_first_word(&p, &word, NULL, EXTRACT_RETAIN_ESCAPE);
                        if (r < 0)
                                return r;
                        if (r == 0)
                                break;

                        for (CGroupIOAccountingMetric i = 0; i < _CGROUP_IO_ACCOUNTING_METRIC_MAX; i++) {
                                const char *x;

                                x = startswith(word, field_names[i]);
                                if (x) {
                                        uint64_t w;

                                        r = safe_atou64(x, &w);
                                        if (r < 0)
                                                return r;

                                        /* Sum up the stats of all devices */
                                        acc[i] += w;
                                        break;
                                }
                        }
                }
        }

        memcpy(ret, acc, sizeof(acc));
        return 0;
}

int unit_get_io_accounting(
                Unit *u,
                CGroupIOAccountingMetric metric,
                uint64_t *ret) {

        uint64_t raw[_CGROUP_IO_ACCOUNTING_METRIC_MAX];
        int r;

        /*
         * Retrieve an IO counter, subtracting the value of the counter value at the time the unit was started.
         * If ret == NULL and metric == _<...>_INVALID, no return value is expected (refresh the caches only).
         */

        assert(u);
        assert(metric >= 0 || (!ret && metric == _CGROUP_IO_ACCOUNTING_METRIC_INVALID));
        assert(metric < _CGROUP_IO_ACCOUNTING_METRIC_MAX);

        if (!UNIT_CGROUP_BOOL(u, io_accounting))
                return -ENODATA;

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return -ENODATA;

        r = unit_get_io_accounting_raw(u, crt, raw);
        if (r == -ENODATA && metric >= 0 && crt->io_accounting_last[metric] != UINT64_MAX)
                goto done;
        if (r < 0)
                return r;

        for (CGroupIOAccountingMetric i = 0; i < _CGROUP_IO_ACCOUNTING_METRIC_MAX; i++) {
                /* Saturated subtraction */
                if (raw[i] > crt->io_accounting_base[i])
                        crt->io_accounting_last[i] = raw[i] - crt->io_accounting_base[i];
                else
                        crt->io_accounting_last[i] = 0;
        }

done:
        if (ret)
                *ret = crt->io_accounting_last[metric];

        return 0;
}

static int unit_reset_cpu_accounting(Unit *unit, CGroupRuntime *crt) {
        int r;

        assert(crt);

        crt->cpu_usage_base = 0;
        crt->cpu_usage_last = NSEC_INFINITY;

        if (unit) {
                r = unit_get_cpu_usage_raw(unit, crt, &crt->cpu_usage_base);
                if (r < 0 && r != -ENODATA)
                        return r;
        }

        return 0;
}

static int unit_reset_io_accounting(Unit *unit, CGroupRuntime *crt) {
        int r;

        assert(crt);

        zero(crt->io_accounting_base);
        FOREACH_ELEMENT(i, crt->io_accounting_last)
                *i = UINT64_MAX;

        if (unit) {
                r = unit_get_io_accounting_raw(unit, crt, crt->io_accounting_base);
                if (r < 0 && r != -ENODATA)
                        return r;
        }

        return 0;
}

static void cgroup_runtime_reset_memory_accounting_last(CGroupRuntime *crt) {
        assert(crt);

        FOREACH_ELEMENT(i, crt->memory_accounting_last)
                *i = UINT64_MAX;
}

static int cgroup_runtime_reset_ip_accounting(CGroupRuntime *crt) {
        int r = 0;

        assert(crt);

        if (crt->ip_accounting_ingress_map_fd >= 0)
                RET_GATHER(r, bpf_firewall_reset_accounting(crt->ip_accounting_ingress_map_fd));

        if (crt->ip_accounting_egress_map_fd >= 0)
                RET_GATHER(r, bpf_firewall_reset_accounting(crt->ip_accounting_egress_map_fd));

        zero(crt->ip_accounting_extra);

        return r;
}

int unit_reset_accounting(Unit *u) {
        int r = 0;

        assert(u);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return 0;

        cgroup_runtime_reset_memory_accounting_last(crt);
        RET_GATHER(r, unit_reset_cpu_accounting(u, crt));
        RET_GATHER(r, unit_reset_io_accounting(u, crt));
        RET_GATHER(r, cgroup_runtime_reset_ip_accounting(crt));

        return r;
}

bool unit_invalidate_cgroup(Unit *u, CGroupMask m) {
        assert(u);

        if (!UNIT_HAS_CGROUP_CONTEXT(u))
                return false;

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return false;

        /* If all controllers shall be invalidated, let's unconditionally submit the unit to realize queue.
         * We initialize the field to _CGROUP_MASK_ALL after all, and semantically it makes sense to use
         * it as a special signal to forcibly re-realize cgroup. */
        if (m != _CGROUP_MASK_ALL &&
            FLAGS_SET(crt->cgroup_invalidated_mask, m)) /* NOP? */
                return false;

        crt->cgroup_invalidated_mask |= m;
        unit_add_to_cgroup_realize_queue(u);

        return true;
}

void unit_invalidate_cgroup_bpf_firewall(Unit *u) {
        assert(u);

        if (!unit_invalidate_cgroup(u, CGROUP_MASK_BPF_FIREWALL))
                return;

        /* If we are a slice unit, we also need to put compile a new BPF program for all our children, as the IP access
         * list of our children includes our own. */
        if (u->type == UNIT_SLICE) {
                Unit *member;

                UNIT_FOREACH_DEPENDENCY(member, u, UNIT_ATOM_SLICE_OF)
                        unit_invalidate_cgroup_bpf_firewall(member);
        }
}

void unit_cgroup_catchup(Unit *u) {
        assert(u);

        if (!UNIT_HAS_CGROUP_CONTEXT(u))
                return;

        /* We dropped the inotify watch during reexec/reload, so we need to
         * check these as they may have changed.
         * Note that (currently) the kernel doesn't actually update cgroup
         * file modification times, so we can't just serialize and then check
         * the mtime for file(s) we are interested in. */
        (void) unit_check_cgroup_events(u);
        unit_add_to_cgroup_oom_queue(u);
}

bool unit_cgroup_delegate(Unit *u) {
        CGroupContext *c;

        assert(u);

        if (!UNIT_VTABLE(u)->can_delegate)
                return false;

        c = unit_get_cgroup_context(u);
        if (!c)
                return false;

        return c->delegate;
}

void manager_invalidate_startup_units(Manager *m) {
        Unit *u;

        assert(m);

        SET_FOREACH(u, m->startup_units)
                unit_invalidate_cgroup(u, CGROUP_MASK_CPU|CGROUP_MASK_IO|CGROUP_MASK_CPUSET);
}

static int unit_cgroup_freezer_kernel_state(Unit *u, FreezerState *ret) {
        _cleanup_free_ char *val = NULL;
        FreezerState s;
        int r;

        assert(u);
        assert(ret);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return -EOWNERDEAD;

        r = cg_get_keyed_attribute(
                        SYSTEMD_CGROUP_CONTROLLER,
                        crt->cgroup_path,
                        "cgroup.events",
                        STRV_MAKE("frozen"),
                        &val);
        if (r < 0)
                return r;

        if (streq(val, "0"))
                s = FREEZER_RUNNING;
        else if (streq(val, "1"))
                s = FREEZER_FROZEN;
        else {
                log_unit_debug(u, "Unexpected cgroup frozen state: %s", val);
                s = _FREEZER_STATE_INVALID;
        }

        *ret = s;
        return 0;
}

int unit_cgroup_freezer_action(Unit *u, FreezerAction action) {
        _cleanup_free_ char *path = NULL;
        FreezerState current, next, objective;
        bool action_in_progress = false;
        int r;

        assert(u);
        assert(action >= 0);
        assert(action < _FREEZER_ACTION_MAX);

        unit_next_freezer_state(u, action, &next, &objective);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                /* No realized cgroup = nothing to freeze */
                goto finish;

        r = unit_cgroup_freezer_kernel_state(u, &current);
        if (r < 0)
                return r;

        if (current == objective) {
                if (objective == FREEZER_FROZEN)
                        goto finish;

                /* Skip thaw only if no freeze operation was in flight */
                if (IN_SET(u->freezer_state, FREEZER_RUNNING, FREEZER_THAWING))
                        goto finish;
        } else
                action_in_progress = true;

        if (next == freezer_state_finish(next)) {
                /* We're directly transitioning into a finished state, which in theory means that
                 * the cgroup's current state already matches the objective and thus we'd return 0.
                 * But, reality shows otherwise (such case would have been handled by current == objective
                 * branch above). This indicates that our freezer_state tracking has diverged
                 * from the real state of the cgroup, which can happen if someone meddles with the
                 * cgroup from underneath us. This really shouldn't happen during normal operation,
                 * though. So, let's warn about it and fix up the state to be valid */

                log_unit_warning(u, "Unit wants to transition to %s freezer state but cgroup is unexpectedly %s, fixing up.",
                                 freezer_state_to_string(next), freezer_state_to_string(current) ?: "(invalid)");

                if (next == FREEZER_FROZEN)
                        next = FREEZER_FREEZING;
                else if (next == FREEZER_FROZEN_BY_PARENT)
                        next = FREEZER_FREEZING_BY_PARENT;
                else if (next == FREEZER_RUNNING)
                        next = FREEZER_THAWING;
                else
                        assert_not_reached();
        }

        r = cg_get_path(SYSTEMD_CGROUP_CONTROLLER, crt->cgroup_path, "cgroup.freeze", &path);
        if (r < 0)
                return r;

        r = write_string_file(path, one_zero(objective == FREEZER_FROZEN), WRITE_STRING_FILE_DISABLE_BUFFER);
        if (r < 0)
                return r;

finish:
        if (action_in_progress)
                unit_set_freezer_state(u, next);
        else
                unit_set_freezer_state(u, freezer_state_finish(next));

        return action_in_progress;
}

int unit_get_cpuset(Unit *u, CPUSet *cpus, const char *name) {
        _cleanup_free_ char *v = NULL;
        int r;

        assert(u);
        assert(cpus);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt || !crt->cgroup_path)
                return -ENODATA;

        if ((crt->cgroup_realized_mask & CGROUP_MASK_CPUSET) == 0)
                return -ENODATA;

        r = cg_get_attribute("cpuset", crt->cgroup_path, name, &v);
        if (r == -ENOENT)
                return -ENODATA;
        if (r < 0)
                return r;

        return parse_cpu_set(v, cpus);
}

CGroupRuntime* cgroup_runtime_new(void) {
        _cleanup_(cgroup_runtime_freep) CGroupRuntime *crt = NULL;

        crt = new(CGroupRuntime, 1);
        if (!crt)
                return NULL;

        *crt = (CGroupRuntime) {
                .cgroup_control_inotify_wd = -1,
                .cgroup_memory_inotify_wd = -1,

                .ip_accounting_ingress_map_fd = -EBADF,
                .ip_accounting_egress_map_fd = -EBADF,

                .ipv4_allow_map_fd = -EBADF,
                .ipv6_allow_map_fd = -EBADF,
                .ipv4_deny_map_fd = -EBADF,
                .ipv6_deny_map_fd = -EBADF,

                .cgroup_invalidated_mask = _CGROUP_MASK_ALL,

                .deserialized_cgroup_realized = -1,
        };

        unit_reset_cpu_accounting(/* unit = */ NULL, crt);
        unit_reset_io_accounting(/* unit = */ NULL, crt);
        cgroup_runtime_reset_memory_accounting_last(crt);
        assert_se(cgroup_runtime_reset_ip_accounting(crt) >= 0);

        return TAKE_PTR(crt);
}

CGroupRuntime* cgroup_runtime_free(CGroupRuntime *crt) {
        if (!crt)
                return NULL;

        fdset_free(crt->initial_socket_bind_link_fds);
#if BPF_FRAMEWORK
        bpf_link_free(crt->ipv4_socket_bind_link);
        bpf_link_free(crt->ipv6_socket_bind_link);
#endif
        hashmap_free(crt->bpf_foreign_by_key);

        bpf_program_free(crt->bpf_device_control_installed);

#if BPF_FRAMEWORK
        bpf_link_free(crt->restrict_ifaces_ingress_bpf_link);
        bpf_link_free(crt->restrict_ifaces_egress_bpf_link);
#endif
        fdset_free(crt->initial_restrict_ifaces_link_fds);

        bpf_firewall_close(crt);

        free(crt->cgroup_path);

        return mfree(crt);
}

static const char* const ip_accounting_metric_field_table[_CGROUP_IP_ACCOUNTING_METRIC_MAX] = {
        [CGROUP_IP_INGRESS_BYTES]   = "ip-accounting-ingress-bytes",
        [CGROUP_IP_INGRESS_PACKETS] = "ip-accounting-ingress-packets",
        [CGROUP_IP_EGRESS_BYTES]    = "ip-accounting-egress-bytes",
        [CGROUP_IP_EGRESS_PACKETS]  = "ip-accounting-egress-packets",
};

DEFINE_PRIVATE_STRING_TABLE_LOOKUP(ip_accounting_metric_field, CGroupIPAccountingMetric);

static const char* const io_accounting_metric_field_base_table[_CGROUP_IO_ACCOUNTING_METRIC_MAX] = {
        [CGROUP_IO_READ_BYTES]       = "io-accounting-read-bytes-base",
        [CGROUP_IO_WRITE_BYTES]      = "io-accounting-write-bytes-base",
        [CGROUP_IO_READ_OPERATIONS]  = "io-accounting-read-operations-base",
        [CGROUP_IO_WRITE_OPERATIONS] = "io-accounting-write-operations-base",
};

DEFINE_PRIVATE_STRING_TABLE_LOOKUP(io_accounting_metric_field_base, CGroupIOAccountingMetric);

static const char* const io_accounting_metric_field_last_table[_CGROUP_IO_ACCOUNTING_METRIC_MAX] = {
        [CGROUP_IO_READ_BYTES]       = "io-accounting-read-bytes-last",
        [CGROUP_IO_WRITE_BYTES]      = "io-accounting-write-bytes-last",
        [CGROUP_IO_READ_OPERATIONS]  = "io-accounting-read-operations-last",
        [CGROUP_IO_WRITE_OPERATIONS] = "io-accounting-write-operations-last",
};

DEFINE_PRIVATE_STRING_TABLE_LOOKUP(io_accounting_metric_field_last, CGroupIOAccountingMetric);

static const char* const memory_accounting_metric_field_last_table[_CGROUP_MEMORY_ACCOUNTING_METRIC_CACHED_LAST + 1] = {
        [CGROUP_MEMORY_PEAK]      = "memory-accounting-peak",
        [CGROUP_MEMORY_SWAP_PEAK] = "memory-accounting-swap-peak",
};

DEFINE_PRIVATE_STRING_TABLE_LOOKUP(memory_accounting_metric_field_last, CGroupMemoryAccountingMetric);

static int serialize_cgroup_mask(FILE *f, const char *key, CGroupMask mask) {
        _cleanup_free_ char *s = NULL;
        int r;

        assert(f);
        assert(key);

        if (mask == 0)
                return 0;

        r = cg_mask_to_string(mask, &s);
        if (r < 0)
                return log_error_errno(r, "Failed to format cgroup mask: %m");

        return serialize_item(f, key, s);
}

int cgroup_runtime_serialize(Unit *u, FILE *f, FDSet *fds) {
        int r;

        assert(u);
        assert(f);
        assert(fds);

        CGroupRuntime *crt = unit_get_cgroup_runtime(u);
        if (!crt)
                return 0;

        if (crt->cgroup_path)
                (void) serialize_item(f, "cgroup", crt->cgroup_path);
        if (crt->cgroup_id != 0)
                (void) serialize_item_format(f, "cgroup-id", "%" PRIu64, crt->cgroup_id);

        (void) serialize_cgroup_mask(f, "cgroup-realized-mask", crt->cgroup_realized_mask);
        (void) serialize_cgroup_mask(f, "cgroup-enabled-mask", crt->cgroup_enabled_mask);
        (void) serialize_cgroup_mask(f, "cgroup-invalidated-mask", crt->cgroup_invalidated_mask);

        (void) serialize_item_format(f, "cpu-usage-base", "%" PRIu64, crt->cpu_usage_base);
        if (crt->cpu_usage_last != NSEC_INFINITY)
                (void) serialize_item_format(f, "cpu-usage-last", "%" PRIu64, crt->cpu_usage_last);

        if (crt->managed_oom_kill_last > 0)
                (void) serialize_item_format(f, "managed-oom-kill-last", "%" PRIu64, crt->managed_oom_kill_last);

        if (crt->oom_kill_last > 0)
                (void) serialize_item_format(f, "oom-kill-last", "%" PRIu64, crt->oom_kill_last);

        for (CGroupMemoryAccountingMetric metric = 0; metric <= _CGROUP_MEMORY_ACCOUNTING_METRIC_CACHED_LAST; metric++) {
                uint64_t v;

                r = unit_get_memory_accounting(u, metric, &v);
                if (r >= 0)
                        (void) serialize_item_format(f, memory_accounting_metric_field_last_to_string(metric), "%" PRIu64, v);
        }

        for (CGroupIPAccountingMetric m = 0; m < _CGROUP_IP_ACCOUNTING_METRIC_MAX; m++) {
                uint64_t v;

                r = unit_get_ip_accounting(u, m, &v);
                if (r >= 0)
                        (void) serialize_item_format(f, ip_accounting_metric_field_to_string(m), "%" PRIu64, v);
        }

        for (CGroupIOAccountingMetric im = 0; im < _CGROUP_IO_ACCOUNTING_METRIC_MAX; im++) {
                (void) serialize_item_format(f, io_accounting_metric_field_base_to_string(im), "%" PRIu64, crt->io_accounting_base[im]);

                if (crt->io_accounting_last[im] != UINT64_MAX)
                        (void) serialize_item_format(f, io_accounting_metric_field_last_to_string(im), "%" PRIu64, crt->io_accounting_last[im]);
        }

        (void) bpf_socket_bind_serialize(u, f, fds);

        (void) bpf_program_serialize_attachment(f, fds, "ip-bpf-ingress-installed", crt->ip_bpf_ingress_installed);
        (void) bpf_program_serialize_attachment(f, fds, "ip-bpf-egress-installed", crt->ip_bpf_egress_installed);
        (void) bpf_program_serialize_attachment(f, fds, "bpf-device-control-installed", crt->bpf_device_control_installed);
        (void) bpf_program_serialize_attachment_set(f, fds, "ip-bpf-custom-ingress-installed", crt->ip_bpf_custom_ingress_installed);
        (void) bpf_program_serialize_attachment_set(f, fds, "ip-bpf-custom-egress-installed", crt->ip_bpf_custom_egress_installed);

        (void) bpf_restrict_ifaces_serialize(u, f, fds);

        return 0;
}

#define MATCH_DESERIALIZE(u, key, l, v, parse_func, target)             \
        ({                                                              \
                bool _deserialize_matched = streq(l, key);              \
                if (_deserialize_matched) {                             \
                        CGroupRuntime *crt = unit_setup_cgroup_runtime(u); \
                        if (!crt)                                       \
                                log_oom_debug();                        \
                        else {                                          \
                                int _deserialize_r = parse_func(v);     \
                                if (_deserialize_r < 0)                 \
                                        log_unit_debug_errno(u, _deserialize_r, \
                                                             "Failed to parse \"%s=%s\", ignoring.", l, v); \
                                else                                    \
                                        crt->target = _deserialize_r;   \
                        }                                               \
                }                                                       \
                _deserialize_matched;                                   \
        })

#define MATCH_DESERIALIZE_IMMEDIATE(u, key, l, v, parse_func, target)   \
        ({                                                              \
                 bool _deserialize_matched = streq(l, key);             \
                 if (_deserialize_matched) {                            \
                         CGroupRuntime *crt = unit_setup_cgroup_runtime(u); \
                         if (!crt)                                      \
                                 log_oom_debug();                       \
                         else {                                         \
                                 int _deserialize_r = parse_func(v, &crt->target); \
                                 if (_deserialize_r < 0)                \
                                         log_unit_debug_errno(u, _deserialize_r, \
                                                              "Failed to parse \"%s=%s\", ignoring", l, v); \
                         }                                              \
                 }                                                      \
                _deserialize_matched;                                   \
        })

#define MATCH_DESERIALIZE_METRIC(u, key, l, v, parse_func, target)      \
        ({                                                              \
                bool _deserialize_matched = streq(l, key);              \
                if (_deserialize_matched) {                             \
                        CGroupRuntime *crt = unit_setup_cgroup_runtime(u); \
                        if (!crt)                                       \
                                log_oom_debug();                        \
                        else {                                          \
                                int _deserialize_r = parse_func(v);     \
                                if (_deserialize_r < 0)                 \
                                        log_unit_debug_errno(u, _deserialize_r, \
                                                             "Failed to parse \"%s=%s\", ignoring.", l, v); \
                                else                                    \
                                        crt->target = _deserialize_r;   \
                        }                                               \
                }                                                       \
                _deserialize_matched;                                   \
        })

int cgroup_runtime_deserialize_one(Unit *u, const char *key, const char *value, FDSet *fds) {
        int r;

        assert(u);
        assert(value);

        if (!UNIT_HAS_CGROUP_CONTEXT(u))
                return 0;

        if (MATCH_DESERIALIZE_IMMEDIATE(u, "cpu-usage-base", key, value, safe_atou64, cpu_usage_base))
                return 1;

        if (MATCH_DESERIALIZE_IMMEDIATE(u, "cpu-usage-last", key, value, safe_atou64, cpu_usage_last))
                return 1;

        if (MATCH_DESERIALIZE_IMMEDIATE(u, "managed-oom-kill-last", key, value, safe_atou64, managed_oom_kill_last))
                return 1;

        if (MATCH_DESERIALIZE_IMMEDIATE(u, "oom-kill-last", key, value, safe_atou64, oom_kill_last))
                return 1;

        if (streq(key, "cgroup")) {
                r = unit_set_cgroup_path(u, value);
                if (r < 0)
                        log_unit_debug_errno(u, r, "Failed to set cgroup path %s, ignoring: %m", value);

                return 1;
        }

        if (MATCH_DESERIALIZE_IMMEDIATE(u, "cgroup-id", key, value, safe_atou64, cgroup_id))
                return 1;

        if (MATCH_DESERIALIZE_IMMEDIATE(u, "cgroup-realized", key, value, parse_tristate, deserialized_cgroup_realized))
                return 1;

        if (MATCH_DESERIALIZE_IMMEDIATE(u, "cgroup-realized-mask", key, value, cg_mask_from_string, cgroup_realized_mask))
                return 1;

        if (MATCH_DESERIALIZE_IMMEDIATE(u, "cgroup-enabled-mask", key, value, cg_mask_from_string, cgroup_enabled_mask))
                return 1;

        if (MATCH_DESERIALIZE_IMMEDIATE(u, "cgroup-invalidated-mask", key, value, cg_mask_from_string, cgroup_invalidated_mask))
                return 1;

        if (STR_IN_SET(key, "ipv4-socket-bind-bpf-link-fd", "ipv6-socket-bind-bpf-link-fd")) {
                int fd;

                fd = deserialize_fd(fds, value);
                if (fd >= 0)
                        (void) bpf_socket_bind_add_initial_link_fd(u, fd);

                return 1;
        }

        if (STR_IN_SET(key,
                       "ip-bpf-ingress-installed", "ip-bpf-egress-installed",
                       "bpf-device-control-installed",
                       "ip-bpf-custom-ingress-installed", "ip-bpf-custom-egress-installed")) {

                CGroupRuntime *crt = unit_setup_cgroup_runtime(u);
                if (!crt)
                        log_oom_debug();
                else {
                        if (streq(key, "ip-bpf-ingress-installed"))
                                (void) bpf_program_deserialize_attachment(value, fds, &crt->ip_bpf_ingress_installed);

                        if (streq(key, "ip-bpf-egress-installed"))
                                (void) bpf_program_deserialize_attachment(value, fds, &crt->ip_bpf_egress_installed);

                        if (streq(key, "bpf-device-control-installed"))
                                (void) bpf_program_deserialize_attachment(value, fds, &crt->bpf_device_control_installed);

                        if (streq(key, "ip-bpf-custom-ingress-installed"))
                                (void) bpf_program_deserialize_attachment_set(value, fds, &crt->ip_bpf_custom_ingress_installed);

                        if (streq(key, "ip-bpf-custom-egress-installed"))
                                (void) bpf_program_deserialize_attachment_set(value, fds, &crt->ip_bpf_custom_egress_installed);
                }

                return 1;
        }

        if (streq(key, "restrict-ifaces-bpf-fd")) {
                int fd;

                fd = deserialize_fd(fds, value);
                if (fd >= 0)
                        (void) bpf_restrict_ifaces_add_initial_link_fd(u, fd);
                return 1;
        }

        CGroupMemoryAccountingMetric mm = memory_accounting_metric_field_last_from_string(key);
        if (mm >= 0) {
                uint64_t c;

                r = safe_atou64(value, &c);
                if (r < 0)
                        log_unit_debug(u, "Failed to parse memory accounting last value %s, ignoring.", value);
                else {
                        CGroupRuntime *crt = unit_setup_cgroup_runtime(u);
                        if (!crt)
                                log_oom_debug();
                        else
                                crt->memory_accounting_last[mm] = c;
                }

                return 1;
        }

        CGroupIPAccountingMetric ipm = ip_accounting_metric_field_from_string(key);
        if (ipm >= 0) {
                uint64_t c;

                r = safe_atou64(value, &c);
                if (r < 0)
                        log_unit_debug(u, "Failed to parse IP accounting value %s, ignoring.", value);
                else {
                        CGroupRuntime *crt = unit_setup_cgroup_runtime(u);
                        if (!crt)
                                log_oom_debug();
                        else
                                crt->ip_accounting_extra[ipm] = c;
                }

                return 1;
        }

        CGroupIOAccountingMetric iom = io_accounting_metric_field_base_from_string(key);
        if (iom >= 0) {
                uint64_t c;

                r = safe_atou64(value, &c);
                if (r < 0)
                        log_unit_debug(u, "Failed to parse IO accounting base value %s, ignoring.", value);
                else {
                        CGroupRuntime *crt = unit_setup_cgroup_runtime(u);
                        if (!crt)
                                log_oom_debug();
                        else
                                crt->io_accounting_base[iom] = c;
                }

                return 1;
        }

        iom = io_accounting_metric_field_last_from_string(key);
        if (iom >= 0) {
                uint64_t c;

                r = safe_atou64(value, &c);
                if (r < 0)
                        log_unit_debug(u, "Failed to parse IO accounting last value %s, ignoring.", value);
                else {
                        CGroupRuntime *crt = unit_setup_cgroup_runtime(u);
                        if (!crt)
                                log_oom_debug();
                        else
                                crt->io_accounting_last[iom] = c;
                }
                return 1;
        }

        return 0;
}

static const char* const cgroup_device_policy_table[_CGROUP_DEVICE_POLICY_MAX] = {
        [CGROUP_DEVICE_POLICY_AUTO]   = "auto",
        [CGROUP_DEVICE_POLICY_CLOSED] = "closed",
        [CGROUP_DEVICE_POLICY_STRICT] = "strict",
};

DEFINE_STRING_TABLE_LOOKUP(cgroup_device_policy, CGroupDevicePolicy);

static const char* const cgroup_pressure_watch_table[_CGROUP_PRESSURE_WATCH_MAX] = {
        [CGROUP_PRESSURE_WATCH_NO]   = "no",
        [CGROUP_PRESSURE_WATCH_YES]  = "yes",
        [CGROUP_PRESSURE_WATCH_AUTO] = "auto",
        [CGROUP_PRESSURE_WATCH_SKIP] = "skip",
};

DEFINE_STRING_TABLE_LOOKUP_WITH_BOOLEAN(cgroup_pressure_watch, CGroupPressureWatch, CGROUP_PRESSURE_WATCH_YES);

static const char* const cgroup_ip_accounting_metric_table[_CGROUP_IP_ACCOUNTING_METRIC_MAX] = {
        [CGROUP_IP_INGRESS_BYTES]   = "IPIngressBytes",
        [CGROUP_IP_EGRESS_BYTES]    = "IPEgressBytes",
        [CGROUP_IP_INGRESS_PACKETS] = "IPIngressPackets",
        [CGROUP_IP_EGRESS_PACKETS]  = "IPEgressPackets",
};

DEFINE_STRING_TABLE_LOOKUP(cgroup_ip_accounting_metric, CGroupIPAccountingMetric);

static const char* const cgroup_io_accounting_metric_table[_CGROUP_IO_ACCOUNTING_METRIC_MAX] = {
        [CGROUP_IO_READ_BYTES]       = "IOReadBytes",
        [CGROUP_IO_WRITE_BYTES]      = "IOWriteBytes",
        [CGROUP_IO_READ_OPERATIONS]  = "IOReadOperations",
        [CGROUP_IO_WRITE_OPERATIONS] = "IOWriteOperations",
};

DEFINE_STRING_TABLE_LOOKUP(cgroup_io_accounting_metric, CGroupIOAccountingMetric);

static const char* const cgroup_memory_accounting_metric_table[_CGROUP_MEMORY_ACCOUNTING_METRIC_MAX] = {
        [CGROUP_MEMORY_CURRENT]       = "MemoryCurrent",
        [CGROUP_MEMORY_PEAK]          = "MemoryPeak",
        [CGROUP_MEMORY_SWAP_CURRENT]  = "MemorySwapCurrent",
        [CGROUP_MEMORY_SWAP_PEAK]     = "MemorySwapPeak",
        [CGROUP_MEMORY_ZSWAP_CURRENT] = "MemoryZSwapCurrent",
};

DEFINE_STRING_TABLE_LOOKUP(cgroup_memory_accounting_metric, CGroupMemoryAccountingMetric);

static const char *const cgroup_effective_limit_type_table[_CGROUP_LIMIT_TYPE_MAX] = {
        [CGROUP_LIMIT_MEMORY_MAX]  = "EffectiveMemoryMax",
        [CGROUP_LIMIT_MEMORY_HIGH] = "EffectiveMemoryHigh",
        [CGROUP_LIMIT_TASKS_MAX]   = "EffectiveTasksMax",
};

DEFINE_STRING_TABLE_LOOKUP(cgroup_effective_limit_type, CGroupLimitType);
