path: root/kernel/cgroup/cgroup-v1.c

// SPDX-License-Identifier: GPL-2.0-only
#include "cgroup-internal.h"

#include <linux/ctype.h>
#include <linux/kmod.h>
#include <linux/sort.h>
#include <linux/delay.h>
#include <linux/mm.h>
#include <linux/sched/signal.h>
#include <linux/sched/task.h>
#include <linux/magic.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/vmalloc.h>
#include <linux/delayacct.h>
#include <linux/pid_namespace.h>
#include <linux/cgroupstats.h>
#include <linux/fs_parser.h>

#include <trace/events/cgroup.h>

/*
 * pidlists linger the following amount before being destroyed.  The goal
 * is avoiding frequent destruction in the middle of consecutive read calls
 * Expiring in the middle is a performance problem not a correctness one.
 * 1 sec should be enough.
 */
#define CGROUP_PIDLIST_DESTROY_DELAY	HZ

/* Controllers blocked by the commandline in v1 */
static u16 cgroup_no_v1_mask;

/* disable named v1 mounts */
static bool cgroup_no_v1_named;

/* Show unavailable controllers in /proc/cgroups */
static bool proc_show_all;

/*
 * pidlist destructions need to be flushed on cgroup destruction.  Use a
 * separate workqueue as flush domain.
 */
static struct workqueue_struct *cgroup_pidlist_destroy_wq;

/* protects cgroup_subsys->release_agent_path */
static DEFINE_SPINLOCK(release_agent_path_lock);

bool cgroup1_ssid_disabled(int ssid)
{
	return cgroup_no_v1_mask & (1 << ssid);
}

static bool cgroup1_subsys_absent(struct cgroup_subsys *ss)
{
	/* Check also dfl_cftypes for file-less controllers, i.e. perf_event */
	return ss->legacy_cftypes == NULL && ss->dfl_cftypes;
}

/**
 * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
 * @from: attach to all cgroups of a given task
 * @tsk: the task to be attached
 *
 * Return: %0 on success or a negative errno code on failure
 */
int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
{
	struct cgroup_root *root;
	int retval = 0;

	cgroup_lock();
	cgroup_attach_lock(CGRP_ATTACH_LOCK_GLOBAL, NULL);
	for_each_root(root) {
		struct cgroup *from_cgrp;

		spin_lock_irq(&css_set_lock);
		from_cgrp = task_cgroup_from_root(from,