1// SPDX-License-Identifier: GPL-2.0-only
   2#include "cgroup-internal.h"
   3
   4#include <linux/ctype.h>
   5#include <linux/kmod.h>
   6#include <linux/sort.h>
   7#include <linux/delay.h>
   8#include <linux/mm.h>
   9#include <linux/sched/signal.h>
  10#include <linux/sched/task.h>
  11#include <linux/magic.h>
  12#include <linux/slab.h>
  13#include <linux/vmalloc.h>
  14#include <linux/delayacct.h>
  15#include <linux/pid_namespace.h>
  16#include <linux/cgroupstats.h>
  17#include <linux/fs_parser.h>
  18
  19#include <trace/events/cgroup.h>
  20
 
 
  21/*
  22 * pidlists linger the following amount before being destroyed.  The goal
  23 * is avoiding frequent destruction in the middle of consecutive read calls
  24 * Expiring in the middle is a performance problem not a correctness one.
  25 * 1 sec should be enough.
  26 */
  27#define CGROUP_PIDLIST_DESTROY_DELAY	HZ
  28
  29/* Controllers blocked by the commandline in v1 */
  30static u16 cgroup_no_v1_mask;
  31
  32/* disable named v1 mounts */
  33static bool cgroup_no_v1_named;
  34
  35/*
  36 * pidlist destructions need to be flushed on cgroup destruction.  Use a
  37 * separate workqueue as flush domain.
  38 */
  39static struct workqueue_struct *cgroup_pidlist_destroy_wq;
  40
  41/* protects cgroup_subsys->release_agent_path */
 
 
 
  42static DEFINE_SPINLOCK(release_agent_path_lock);
  43
  44bool cgroup1_ssid_disabled(int ssid)
  45{
  46	return cgroup_no_v1_mask & (1 << ssid);
  47}
  48
  49static bool cgroup1_subsys_absent(struct cgroup_subsys *ss)
  50{
  51	/* Check also dfl_cftypes for file-less controllers, i.e. perf_event */
  52	return ss->legacy_cftypes == NULL && ss->dfl_cftypes;
  53}
  54
  55/**
  56 * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
  57 * @from: attach to all cgroups of a given task
  58 * @tsk: the task to be attached
  59 *
  60 * Return: %0 on success or a negative errno code on failure
  61 */
  62int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
  63{
  64	struct cgroup_root *root;
  65	int retval = 0;
  66
  67	cgroup_lock();
  68	cgroup_attach_lock(true);
  69	for_each_root(root) {
  70		struct cgroup *from_cgrp;
  71
 
 
 
  72		spin_lock_irq(&css_set_lock);
  73		from_cgrp = task_cgroup_from_root(from, root);
  74		spin_unlock_irq(&css_set_lock);
  75
  76		retval = cgroup_attach_task(from_cgrp, tsk, false);
  77		if (retval)
  78			break;
  79	}
  80	cgroup_attach_unlock(true);
  81	cgroup_unlock();
  82
  83	return retval;
  84}
  85EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
  86
  87/**
  88 * cgroup_transfer_tasks - move tasks from one cgroup to another
  89 * @to: cgroup to which the tasks will be moved
  90 * @from: cgroup in which the tasks currently reside
  91 *
  92 * Locking rules between cgroup_post_fork() and the migration path
  93 * guarantee that, if a task is forking while being migrated, the new child
  94 * is guaranteed to be either visible in the source cgroup after the
  95 * parent's migration is complete or put into the target cgroup.  No task
  96 * can slip out of migration through forking.
  97 *
  98 * Return: %0 on success or a negative errno code on failure
  99 */
 100int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
 101{
 102	DEFINE_CGROUP_MGCTX(mgctx);
 103	struct cgrp_cset_link *link;
 104	struct css_task_iter it;
 105	struct task_struct *task;
 106	int ret;
 107
 108	if (cgroup_on_dfl(to))
 109		return -EINVAL;
 110
 111	ret = cgroup_migrate_vet_dst(to);
 112	if (ret)
 113		return ret;
 114
 115	cgroup_lock();
 116
 117	cgroup_attach_lock(true);
 118
 119	/* all tasks in @from are being moved, all csets are source */
 120	spin_lock_irq(&css_set_lock);
 121	list_for_each_entry(link, &from->cset_links, cset_link)
 122		cgroup_migrate_add_src(link->cset, to, &mgctx);
 123	spin_unlock_irq(&css_set_lock);
 124
 125	ret = cgroup_migrate_prepare_dst(&mgctx);
 126	if (ret)
 127		goto out_err;
 128
 129	/*
 130	 * Migrate tasks one-by-one until @from is empty.  This fails iff
 131	 * ->can_attach() fails.
 132	 */
 133	do {
 134		css_task_iter_start(&from->self, 0, &it);
 135
 136		do {
 137			task = css_task_iter_next(&it);
 138		} while (task && (task->flags & PF_EXITING));
 139
 140		if (task)
 141			get_task_struct(task);
 142		css_task_iter_end(&it);
 143
 144		if (task) {
 145			ret = cgroup_migrate(task, false, &mgctx);
 146			if (!ret)
 147				TRACE_CGROUP_PATH(transfer_tasks, to, task, false);
 148			put_task_struct(task);
 149		}
 150	} while (task && !ret);
 151out_err:
 152	cgroup_migrate_finish(&mgctx);
 153	cgroup_attach_unlock(true);
 154	cgroup_unlock();
 155	return ret;
 156}
 157
 158/*
 159 * Stuff for reading the 'tasks'/'procs' files.
 160 *
 161 * Reading this file can return large amounts of data if a cgroup has
 162 * *lots* of attached tasks. So it may need several calls to read(),
 163 * but we cannot guarantee that the information we produce is correct
 164 * unless we produce it entirely atomically.
 165 *
 166 */
 167
 168/* which pidlist file are we talking about? */
 169enum cgroup_filetype {
 170	CGROUP_FILE_PROCS,
 171	CGROUP_FILE_TASKS,
 172};
 173
 174/*
 175 * A pidlist is a list of pids that virtually represents the contents of one
 176 * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
 177 * a pair (one each for procs, tasks) for each pid namespace that's relevant
 178 * to the cgroup.
 179 */
 180struct cgroup_pidlist {
 181	/*
 182	 * used to find which pidlist is wanted. doesn't change as long as
 183	 * this particular list stays in the list.
 184	*/
 185	struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
 186	/* array of xids */
 187	pid_t *list;
 188	/* how many elements the above list has */
 189	int length;
 190	/* each of these stored in a list by its cgroup */
 191	struct list_head links;
 192	/* pointer to the cgroup we belong to, for list removal purposes */
 193	struct cgroup *owner;
 194	/* for delayed destruction */
 195	struct delayed_work destroy_dwork;
 196};
 197
 198/*
 199 * Used to destroy all pidlists lingering waiting for destroy timer.  None
 200 * should be left afterwards.
 201 */
 202void cgroup1_pidlist_destroy_all(struct cgroup *cgrp)
 203{
 204	struct cgroup_pidlist *l, *tmp_l;
 205
 206	mutex_lock(&cgrp->pidlist_mutex);
 207	list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
 208		mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
 209	mutex_unlock(&cgrp->pidlist_mutex);
 210
 211	flush_workqueue(cgroup_pidlist_destroy_wq);
 212	BUG_ON(!list_empty(&cgrp->pidlists));
 213}
 214
 215static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
 216{
 217	struct delayed_work *dwork = to_delayed_work(work);
 218	struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
 219						destroy_dwork);
 220	struct cgroup_pidlist *tofree = NULL;
 221
 222	mutex_lock(&l->owner->pidlist_mutex);
 223
 224	/*
 225	 * Destroy iff we didn't get queued again.  The state won't change
 226	 * as destroy_dwork can only be queued while locked.
 227	 */
 228	if (!delayed_work_pending(dwork)) {
 229		list_del(&l->links);
 230		kvfree(l->list);
 231		put_pid_ns(l->key.ns);
 232		tofree = l;
 233	}
 234
 235	mutex_unlock(&l->owner->pidlist_mutex);
 236	kfree(tofree);
 237}
 238
 239/*
 240 * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
 241 * Returns the number of unique elements.
 242 */
 243static int pidlist_uniq(pid_t *list, int length)
 244{
 245	int src, dest = 1;
 246
 247	/*
 248	 * we presume the 0th element is unique, so i starts at 1. trivial
 249	 * edge cases first; no work needs to be done for either
 250	 */
 251	if (length == 0 || length == 1)
 252		return length;
 253	/* src and dest walk down the list; dest counts unique elements */
 254	for (src = 1; src < length; src++) {
 255		/* find next unique element */
 256		while (list[src] == list[src-1]) {
 257			src++;
 258			if (src == length)
 259				goto after;
 260		}
 261		/* dest always points to where the next unique element goes */
 262		list[dest] = list[src];
 263		dest++;
 264	}
 265after:
 266	return dest;
 267}
 268
 269/*
 270 * The two pid files - task and cgroup.procs - guaranteed that the result
 271 * is sorted, which forced this whole pidlist fiasco.  As pid order is
 272 * different per namespace, each namespace needs differently sorted list,
 273 * making it impossible to use, for example, single rbtree of member tasks
 274 * sorted by task pointer.  As pidlists can be fairly large, allocating one
 275 * per open file is dangerous, so cgroup had to implement shared pool of
 276 * pidlists keyed by cgroup and namespace.
 277 */
 278static int cmppid(const void *a, const void *b)
 279{
 280	return *(pid_t *)a - *(pid_t *)b;
 281}
 282
 283static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
 284						  enum cgroup_filetype type)
 285{
 286	struct cgroup_pidlist *l;
 287	/* don't need task_nsproxy() if we're looking at ourself */
 288	struct pid_namespace *ns = task_active_pid_ns(current);
 289
 290	lockdep_assert_held(&cgrp->pidlist_mutex);
 291
 292	list_for_each_entry(l, &cgrp->pidlists, links)
 293		if (l->key.type == type && l->key.ns == ns)
 294			return l;
 295	return NULL;
 296}
 297
 298/*
 299 * find the appropriate pidlist for our purpose (given procs vs tasks)
 300 * returns with the lock on that pidlist already held, and takes care
 301 * of the use count, or returns NULL with no locks held if we're out of
 302 * memory.
 303 */
 304static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
 305						enum cgroup_filetype type)
 306{
 307	struct cgroup_pidlist *l;
 308
 309	lockdep_assert_held(&cgrp->pidlist_mutex);
 310
 311	l = cgroup_pidlist_find(cgrp, type);
 312	if (l)
 313		return l;
 314
 315	/* entry not found; create a new one */
 316	l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
 317	if (!l)
 318		return l;
 319
 320	INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
 321	l->key.type = type;
 322	/* don't need task_nsproxy() if we're looking at ourself */
 323	l->key.ns = get_pid_ns(task_active_pid_ns(current));
 324	l->owner = cgrp;
 325	list_add(&l->links, &cgrp->pidlists);
 326	return l;
 327}
 328
 329/*
 330 * Load a cgroup's pidarray with either procs' tgids or tasks' pids
 331 */
 332static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
 333			      struct cgroup_pidlist **lp)
 334{
 335	pid_t *array;
 336	int length;
 337	int pid, n = 0; /* used for populating the array */
 338	struct css_task_iter it;
 339	struct task_struct *tsk;
 340	struct cgroup_pidlist *l;
 341
 342	lockdep_assert_held(&cgrp->pidlist_mutex);
 343
 344	/*
 345	 * If cgroup gets more users after we read count, we won't have
 346	 * enough space - tough.  This race is indistinguishable to the
 347	 * caller from the case that the additional cgroup users didn't
 348	 * show up until sometime later on.
 349	 */
 350	length = cgroup_task_count(cgrp);
 351	array = kvmalloc_array(length, sizeof(pid_t), GFP_KERNEL);
 352	if (!array)
 353		return -ENOMEM;
 354	/* now, populate the array */
 355	css_task_iter_start(&cgrp->self, 0, &it);
 356	while ((tsk = css_task_iter_next(&it))) {
 357		if (unlikely(n == length))
 358			break;
 359		/* get tgid or pid for procs or tasks file respectively */
 360		if (type == CGROUP_FILE_PROCS)
 361			pid = task_tgid_vnr(tsk);
 362		else
 363			pid = task_pid_vnr(tsk);
 364		if (pid > 0) /* make sure to only use valid results */
 365			array[n++] = pid;
 366	}
 367	css_task_iter_end(&it);
 368	length = n;
 369	/* now sort & strip out duplicates (tgids or recycled thread PIDs) */
 370	sort(array, length, sizeof(pid_t), cmppid, NULL);
 371	length = pidlist_uniq(array, length);
 
 372
 373	l = cgroup_pidlist_find_create(cgrp, type);
 374	if (!l) {
 375		kvfree(array);
 376		return -ENOMEM;
 377	}
 378
 379	/* store array, freeing old if necessary */
 380	kvfree(l->list);
 381	l->list = array;
 382	l->length = length;
 383	*lp = l;
 384	return 0;
 385}
 386
 387/*
 388 * seq_file methods for the tasks/procs files. The seq_file position is the
 389 * next pid to display; the seq_file iterator is a pointer to the pid
 390 * in the cgroup->l->list array.
 391 */
 392
 393static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
 394{
 395	/*
 396	 * Initially we receive a position value that corresponds to
 397	 * one more than the last pid shown (or 0 on the first call or
 398	 * after a seek to the start). Use a binary-search to find the
 399	 * next pid to display, if any
 400	 */
 401	struct kernfs_open_file *of = s->private;
 402	struct cgroup_file_ctx *ctx = of->priv;
 403	struct cgroup *cgrp = seq_css(s)->cgroup;
 404	struct cgroup_pidlist *l;
 405	enum cgroup_filetype type = seq_cft(s)->private;
 406	int index = 0, pid = *pos;
 407	int *iter, ret;
 408
 409	mutex_lock(&cgrp->pidlist_mutex);
 410
 411	/*
 412	 * !NULL @ctx->procs1.pidlist indicates that this isn't the first
 413	 * start() after open. If the matching pidlist is around, we can use
 414	 * that. Look for it. Note that @ctx->procs1.pidlist can't be used
 415	 * directly. It could already have been destroyed.
 416	 */
 417	if (ctx->procs1.pidlist)
 418		ctx->procs1.pidlist = cgroup_pidlist_find(cgrp, type);
 419
 420	/*
 421	 * Either this is the first start() after open or the matching
 422	 * pidlist has been destroyed inbetween.  Create a new one.
 423	 */
 424	if (!ctx->procs1.pidlist) {
 425		ret = pidlist_array_load(cgrp, type, &ctx->procs1.pidlist);
 
 426		if (ret)
 427			return ERR_PTR(ret);
 428	}
 429	l = ctx->procs1.pidlist;
 430
 431	if (pid) {
 432		int end = l->length;
 433
 434		while (index < end) {
 435			int mid = (index + end) / 2;
 436			if (l->list[mid] == pid) {
 437				index = mid;
 438				break;
 439			} else if (l->list[mid] < pid)
 440				index = mid + 1;
 441			else
 442				end = mid;
 443		}
 444	}
 445	/* If we're off the end of the array, we're done */
 446	if (index >= l->length)
 447		return NULL;
 448	/* Update the abstract position to be the actual pid that we found */
 449	iter = l->list + index;
 450	*pos = *iter;
 451	return iter;
 452}
 453
 454static void cgroup_pidlist_stop(struct seq_file *s, void *v)
 455{
 456	struct kernfs_open_file *of = s->private;
 457	struct cgroup_file_ctx *ctx = of->priv;
 458	struct cgroup_pidlist *l = ctx->procs1.pidlist;
 459
 460	if (l)
 461		mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
 462				 CGROUP_PIDLIST_DESTROY_DELAY);
 463	mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
 464}
 465
 466static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
 467{
 468	struct kernfs_open_file *of = s->private;
 469	struct cgroup_file_ctx *ctx = of->priv;
 470	struct cgroup_pidlist *l = ctx->procs1.pidlist;
 471	pid_t *p = v;
 472	pid_t *end = l->list + l->length;
 473	/*
 474	 * Advance to the next pid in the array. If this goes off the
 475	 * end, we're done
 476	 */
 477	p++;
 478	if (p >= end) {
 479		(*pos)++;
 480		return NULL;
 481	} else {
 482		*pos = *p;
 483		return p;
 484	}
 485}
 486
 487static int cgroup_pidlist_show(struct seq_file *s, void *v)
 488{
 489	seq_printf(s, "%d\n", *(int *)v);
 490
 491	return 0;
 492}
 493
 494static ssize_t __cgroup1_procs_write(struct kernfs_open_file *of,
 495				     char *buf, size_t nbytes, loff_t off,
 496				     bool threadgroup)
 497{
 498	struct cgroup *cgrp;
 499	struct task_struct *task;
 500	const struct cred *cred, *tcred;
 501	ssize_t ret;
 502	bool locked;
 503
 504	cgrp = cgroup_kn_lock_live(of->kn, false);
 505	if (!cgrp)
 506		return -ENODEV;
 507
 508	task = cgroup_procs_write_start(buf, threadgroup, &locked);
 509	ret = PTR_ERR_OR_ZERO(task);
 510	if (ret)
 511		goto out_unlock;
 512
 513	/*
 514	 * Even if we're attaching all tasks in the thread group, we only need
 515	 * to check permissions on one of them. Check permissions using the
 516	 * credentials from file open to protect against inherited fd attacks.
 517	 */
 518	cred = of->file->f_cred;
 519	tcred = get_task_cred(task);
 520	if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
 521	    !uid_eq(cred->euid, tcred->uid) &&
 522	    !uid_eq(cred->euid, tcred->suid))
 523		ret = -EACCES;
 524	put_cred(tcred);
 525	if (ret)
 526		goto out_finish;
 527
 528	ret = cgroup_attach_task(cgrp, task, threadgroup);
 529
 530out_finish:
 531	cgroup_procs_write_finish(task, locked);
 532out_unlock:
 533	cgroup_kn_unlock(of->kn);
 534
 535	return ret ?: nbytes;
 536}
 537
 538static ssize_t cgroup1_procs_write(struct kernfs_open_file *of,
 539				   char *buf, size_t nbytes, loff_t off)
 540{
 541	return __cgroup1_procs_write(of, buf, nbytes, off, true);
 542}
 543
 544static ssize_t cgroup1_tasks_write(struct kernfs_open_file *of,
 545				   char *buf, size_t nbytes, loff_t off)
 546{
 547	return __cgroup1_procs_write(of, buf, nbytes, off, false);
 548}
 549
 550static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
 551					  char *buf, size_t nbytes, loff_t off)
 552{
 553	struct cgroup *cgrp;
 554	struct cgroup_file_ctx *ctx;
 555
 556	BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
 557
 558	/*
 559	 * Release agent gets called with all capabilities,
 560	 * require capabilities to set release agent.
 561	 */
 562	ctx = of->priv;
 563	if ((ctx->ns->user_ns != &init_user_ns) ||
 564	    !file_ns_capable(of->file, &init_user_ns, CAP_SYS_ADMIN))
 565		return -EPERM;
 566
 567	cgrp = cgroup_kn_lock_live(of->kn, false);
 568	if (!cgrp)
 569		return -ENODEV;
 570	spin_lock(&release_agent_path_lock);
 571	strscpy(cgrp->root->release_agent_path, strstrip(buf),
 572		sizeof(cgrp->root->release_agent_path));
 573	spin_unlock(&release_agent_path_lock);
 574	cgroup_kn_unlock(of->kn);
 575	return nbytes;
 576}
 577
 578static int cgroup_release_agent_show(struct seq_file *seq, void *v)
 579{
 580	struct cgroup *cgrp = seq_css(seq)->cgroup;
 581
 582	spin_lock(&release_agent_path_lock);
 583	seq_puts(seq, cgrp->root->release_agent_path);
 584	spin_unlock(&release_agent_path_lock);
 585	seq_putc(seq, '\n');
 586	return 0;
 587}
 588
 589static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
 590{
 591	seq_puts(seq, "0\n");
 592	return 0;
 593}
 594
 595static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
 596					 struct cftype *cft)
 597{
 598	return notify_on_release(css->cgroup);
 599}
 600
 601static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
 602					  struct cftype *cft, u64 val)
 603{
 604	if (val)
 605		set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
 606	else
 607		clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
 608	return 0;
 609}
 610
 611static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
 612				      struct cftype *cft)
 613{
 614	return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
 615}
 616
 617static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
 618				       struct cftype *cft, u64 val)
 619{
 620	if (val)
 621		set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
 622	else
 623		clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
 624	return 0;
 625}
 626
 627/* cgroup core interface files for the legacy hierarchies */
 628struct cftype cgroup1_base_files[] = {
 629	{
 630		.name = "cgroup.procs",
 631		.seq_start = cgroup_pidlist_start,
 632		.seq_next = cgroup_pidlist_next,
 633		.seq_stop = cgroup_pidlist_stop,
 634		.seq_show = cgroup_pidlist_show,
 635		.private = CGROUP_FILE_PROCS,
 636		.write = cgroup1_procs_write,
 637	},
 638	{
 639		.name = "cgroup.clone_children",
 640		.read_u64 = cgroup_clone_children_read,
 641		.write_u64 = cgroup_clone_children_write,
 642	},
 643	{
 644		.name = "cgroup.sane_behavior",
 645		.flags = CFTYPE_ONLY_ON_ROOT,
 646		.seq_show = cgroup_sane_behavior_show,
 647	},
 648	{
 649		.name = "tasks",
 650		.seq_start = cgroup_pidlist_start,
 651		.seq_next = cgroup_pidlist_next,
 652		.seq_stop = cgroup_pidlist_stop,
 653		.seq_show = cgroup_pidlist_show,
 654		.private = CGROUP_FILE_TASKS,
 655		.write = cgroup1_tasks_write,
 656	},
 657	{
 658		.name = "notify_on_release",
 659		.read_u64 = cgroup_read_notify_on_release,
 660		.write_u64 = cgroup_write_notify_on_release,
 661	},
 662	{
 663		.name = "release_agent",
 664		.flags = CFTYPE_ONLY_ON_ROOT,
 665		.seq_show = cgroup_release_agent_show,
 666		.write = cgroup_release_agent_write,
 667		.max_write_len = PATH_MAX - 1,
 668	},
 669	{ }	/* terminate */
 670};
 671
 672/* Display information about each subsystem and each hierarchy */
 673int proc_cgroupstats_show(struct seq_file *m, void *v)
 674{
 675	struct cgroup_subsys *ss;
 676	int i;
 677
 678	seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
 679	/*
 680	 * Grab the subsystems state racily. No need to add avenue to
 681	 * cgroup_mutex contention.
 
 682	 */
 
 683
 684	for_each_subsys(ss, i) {
 685		if (cgroup1_subsys_absent(ss))
 686			continue;
 687		seq_printf(m, "%s\t%d\t%d\t%d\n",
 688			   ss->legacy_name, ss->root->hierarchy_id,
 689			   atomic_read(&ss->root->nr_cgrps),
 690			   cgroup_ssid_enabled(i));
 691	}
 692
 
 693	return 0;
 694}
 695
 696/**
 697 * cgroupstats_build - build and fill cgroupstats
 698 * @stats: cgroupstats to fill information into
 699 * @dentry: A dentry entry belonging to the cgroup for which stats have
 700 * been requested.
 701 *
 702 * Build and fill cgroupstats so that taskstats can export it to user
 703 * space.
 704 *
 705 * Return: %0 on success or a negative errno code on failure
 706 */
 707int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
 708{
 709	struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
 710	struct cgroup *cgrp;
 711	struct css_task_iter it;
 712	struct task_struct *tsk;
 713
 714	/* it should be kernfs_node belonging to cgroupfs and is a directory */
 715	if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
 716	    kernfs_type(kn) != KERNFS_DIR)
 717		return -EINVAL;
 718
 
 
 719	/*
 720	 * We aren't being called from kernfs and there's no guarantee on
 721	 * @kn->priv's validity.  For this and css_tryget_online_from_dir(),
 722	 * @kn->priv is RCU safe.  Let's do the RCU dancing.
 723	 */
 724	rcu_read_lock();
 725	cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
 726	if (!cgrp || !cgroup_tryget(cgrp)) {
 727		rcu_read_unlock();
 
 728		return -ENOENT;
 729	}
 730	rcu_read_unlock();
 731
 732	css_task_iter_start(&cgrp->self, 0, &it);
 733	while ((tsk = css_task_iter_next(&it))) {
 734		switch (READ_ONCE(tsk->__state)) {
 735		case TASK_RUNNING:
 736			stats->nr_running++;
 737			break;
 738		case TASK_INTERRUPTIBLE:
 739			stats->nr_sleeping++;
 740			break;
 741		case TASK_UNINTERRUPTIBLE:
 742			stats->nr_uninterruptible++;
 743			break;
 744		case TASK_STOPPED:
 745			stats->nr_stopped++;
 746			break;
 747		default:
 748			if (tsk->in_iowait)
 749				stats->nr_io_wait++;
 750			break;
 751		}
 752	}
 753	css_task_iter_end(&it);
 754
 755	cgroup_put(cgrp);
 756	return 0;
 757}
 758
 759void cgroup1_check_for_release(struct cgroup *cgrp)
 760{
 761	if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
 762	    !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
 763		schedule_work(&cgrp->release_agent_work);
 764}
 765
 766/*
 767 * Notify userspace when a cgroup is released, by running the
 768 * configured release agent with the name of the cgroup (path
 769 * relative to the root of cgroup file system) as the argument.
 770 *
 771 * Most likely, this user command will try to rmdir this cgroup.
 772 *
 773 * This races with the possibility that some other task will be
 774 * attached to this cgroup before it is removed, or that some other
 775 * user task will 'mkdir' a child cgroup of this cgroup.  That's ok.
 776 * The presumed 'rmdir' will fail quietly if this cgroup is no longer
 777 * unused, and this cgroup will be reprieved from its death sentence,
 778 * to continue to serve a useful existence.  Next time it's released,
 779 * we will get notified again, if it still has 'notify_on_release' set.
 780 *
 781 * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
 782 * means only wait until the task is successfully execve()'d.  The
 783 * separate release agent task is forked by call_usermodehelper(),
 784 * then control in this thread returns here, without waiting for the
 785 * release agent task.  We don't bother to wait because the caller of
 786 * this routine has no use for the exit status of the release agent
 787 * task, so no sense holding our caller up for that.
 788 */
 789void cgroup1_release_agent(struct work_struct *work)
 790{
 791	struct cgroup *cgrp =
 792		container_of(work, struct cgroup, release_agent_work);
 793	char *pathbuf, *agentbuf;
 794	char *argv[3], *envp[3];
 795	int ret;
 796
 797	/* snoop agent path and exit early if empty */
 798	if (!cgrp->root->release_agent_path[0])
 799		return;
 800
 801	/* prepare argument buffers */
 802	pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
 803	agentbuf = kmalloc(PATH_MAX, GFP_KERNEL);
 804	if (!pathbuf || !agentbuf)
 805		goto out_free;
 806
 807	spin_lock(&release_agent_path_lock);
 808	strscpy(agentbuf, cgrp->root->release_agent_path, PATH_MAX);
 809	spin_unlock(&release_agent_path_lock);
 810	if (!agentbuf[0])
 811		goto out_free;
 812
 813	ret = cgroup_path_ns(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
 814	if (ret < 0)
 815		goto out_free;
 
 
 816
 817	argv[0] = agentbuf;
 818	argv[1] = pathbuf;
 819	argv[2] = NULL;
 820
 821	/* minimal command environment */
 822	envp[0] = "HOME=/";
 823	envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 824	envp[2] = NULL;
 825
 
 826	call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
 
 
 
 827out_free:
 828	kfree(agentbuf);
 829	kfree(pathbuf);
 830}
 831
 832/*
 833 * cgroup_rename - Only allow simple rename of directories in place.
 834 */
 835static int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
 836			  const char *new_name_str)
 837{
 838	struct cgroup *cgrp = kn->priv;
 839	int ret;
 840
 841	/* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */
 842	if (strchr(new_name_str, '\n'))
 843		return -EINVAL;
 844
 845	if (kernfs_type(kn) != KERNFS_DIR)
 846		return -ENOTDIR;
 847	if (kn->parent != new_parent)
 848		return -EIO;
 849
 850	/*
 851	 * We're gonna grab cgroup_mutex which nests outside kernfs
 852	 * active_ref.  kernfs_rename() doesn't require active_ref
 853	 * protection.  Break them before grabbing cgroup_mutex.
 854	 */
 855	kernfs_break_active_protection(new_parent);
 856	kernfs_break_active_protection(kn);
 857
 858	cgroup_lock();
 859
 860	ret = kernfs_rename(kn, new_parent, new_name_str);
 861	if (!ret)
 862		TRACE_CGROUP_PATH(rename, cgrp);
 863
 864	cgroup_unlock();
 865
 866	kernfs_unbreak_active_protection(kn);
 867	kernfs_unbreak_active_protection(new_parent);
 868	return ret;
 869}
 870
 871static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
 872{
 873	struct cgroup_root *root = cgroup_root_from_kf(kf_root);
 874	struct cgroup_subsys *ss;
 875	int ssid;
 876
 877	for_each_subsys(ss, ssid)
 878		if (root->subsys_mask & (1 << ssid))
 879			seq_show_option(seq, ss->legacy_name, NULL);
 880	if (root->flags & CGRP_ROOT_NOPREFIX)
 881		seq_puts(seq, ",noprefix");
 882	if (root->flags & CGRP_ROOT_XATTR)
 883		seq_puts(seq, ",xattr");
 884	if (root->flags & CGRP_ROOT_CPUSET_V2_MODE)
 885		seq_puts(seq, ",cpuset_v2_mode");
 886	if (root->flags & CGRP_ROOT_FAVOR_DYNMODS)
 887		seq_puts(seq, ",favordynmods");
 888
 889	spin_lock(&release_agent_path_lock);
 890	if (strlen(root->release_agent_path))
 891		seq_show_option(seq, "release_agent",
 892				root->release_agent_path);
 893	spin_unlock(&release_agent_path_lock);
 894
 895	if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
 896		seq_puts(seq, ",clone_children");
 897	if (strlen(root->name))
 898		seq_show_option(seq, "name", root->name);
 899	return 0;
 900}
 901
 902enum cgroup1_param {
 903	Opt_all,
 904	Opt_clone_children,
 905	Opt_cpuset_v2_mode,
 906	Opt_name,
 907	Opt_none,
 908	Opt_noprefix,
 909	Opt_release_agent,
 910	Opt_xattr,
 911	Opt_favordynmods,
 912	Opt_nofavordynmods,
 913};
 914
 915const struct fs_parameter_spec cgroup1_fs_parameters[] = {
 916	fsparam_flag  ("all",		Opt_all),
 917	fsparam_flag  ("clone_children", Opt_clone_children),
 918	fsparam_flag  ("cpuset_v2_mode", Opt_cpuset_v2_mode),
 919	fsparam_string("name",		Opt_name),
 920	fsparam_flag  ("none",		Opt_none),
 921	fsparam_flag  ("noprefix",	Opt_noprefix),
 922	fsparam_string("release_agent",	Opt_release_agent),
 923	fsparam_flag  ("xattr",		Opt_xattr),
 924	fsparam_flag  ("favordynmods",	Opt_favordynmods),
 925	fsparam_flag  ("nofavordynmods", Opt_nofavordynmods),
 926	{}
 927};
 928
 
 
 
 
 
 929int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param)
 930{
 931	struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
 932	struct cgroup_subsys *ss;
 933	struct fs_parse_result result;
 934	int opt, i;
 935
 936	opt = fs_parse(fc, cgroup1_fs_parameters, param, &result);
 937	if (opt == -ENOPARAM) {
 938		int ret;
 939
 940		ret = vfs_parse_fs_param_source(fc, param);
 941		if (ret != -ENOPARAM)
 942			return ret;
 943		for_each_subsys(ss, i) {
 944			if (strcmp(param->key, ss->legacy_name) ||
 945			    cgroup1_subsys_absent(ss))
 946				continue;
 947			if (!cgroup_ssid_enabled(i) || cgroup1_ssid_disabled(i))
 948				return invalfc(fc, "Disabled controller '%s'",
 949					       param->key);
 950			ctx->subsys_mask |= (1 << i);
 951			return 0;
 952		}
 953		return invalfc(fc, "Unknown subsys name '%s'", param->key);
 954	}
 955	if (opt < 0)
 956		return opt;
 957
 958	switch (opt) {
 959	case Opt_none:
 960		/* Explicitly have no subsystems */
 961		ctx->none = true;
 962		break;
 963	case Opt_all:
 964		ctx->all_ss = true;
 965		break;
 966	case Opt_noprefix:
 967		ctx->flags |= CGRP_ROOT_NOPREFIX;
 968		break;
 969	case Opt_clone_children:
 970		ctx->cpuset_clone_children = true;
 971		break;
 972	case Opt_cpuset_v2_mode:
 973		ctx->flags |= CGRP_ROOT_CPUSET_V2_MODE;
 974		break;
 975	case Opt_xattr:
 976		ctx->flags |= CGRP_ROOT_XATTR;
 977		break;
 978	case Opt_favordynmods:
 979		ctx->flags |= CGRP_ROOT_FAVOR_DYNMODS;
 980		break;
 981	case Opt_nofavordynmods:
 982		ctx->flags &= ~CGRP_ROOT_FAVOR_DYNMODS;
 983		break;
 984	case Opt_release_agent:
 985		/* Specifying two release agents is forbidden */
 986		if (ctx->release_agent)
 987			return invalfc(fc, "release_agent respecified");
 988		/*
 989		 * Release agent gets called with all capabilities,
 990		 * require capabilities to set release agent.
 991		 */
 992		if ((fc->user_ns != &init_user_ns) || !capable(CAP_SYS_ADMIN))
 993			return invalfc(fc, "Setting release_agent not allowed");
 994		ctx->release_agent = param->string;
 995		param->string = NULL;
 996		break;
 997	case Opt_name:
 998		/* blocked by boot param? */
 999		if (cgroup_no_v1_named)
1000			return -ENOENT;
1001		/* Can't specify an empty name */
1002		if (!param->size)
1003			return invalfc(fc, "Empty name");
1004		if (param->size > MAX_CGROUP_ROOT_NAMELEN - 1)
1005			return invalfc(fc, "Name too long");
1006		/* Must match [\w.-]+ */
1007		for (i = 0; i < param->size; i++) {
1008			char c = param->string[i];
1009			if (isalnum(c))
1010				continue;
1011			if ((c == '.') || (c == '-') || (c == '_'))
1012				continue;
1013			return invalfc(fc, "Invalid name");
1014		}
1015		/* Specifying two names is forbidden */
1016		if (ctx->name)
1017			return invalfc(fc, "name respecified");
1018		ctx->name = param->string;
1019		param->string = NULL;
1020		break;
1021	}
1022	return 0;
1023}
1024
1025static int check_cgroupfs_options(struct fs_context *fc)
1026{
1027	struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
1028	u16 mask = U16_MAX;
1029	u16 enabled = 0;
1030	struct cgroup_subsys *ss;
1031	int i;
1032
1033#ifdef CONFIG_CPUSETS
1034	mask = ~((u16)1 << cpuset_cgrp_id);
1035#endif
1036	for_each_subsys(ss, i)
1037		if (cgroup_ssid_enabled(i) && !cgroup1_ssid_disabled(i) &&
1038		    !cgroup1_subsys_absent(ss))
1039			enabled |= 1 << i;
1040
1041	ctx->subsys_mask &= enabled;
1042
1043	/*
1044	 * In absence of 'none', 'name=' and subsystem name options,
1045	 * let's default to 'all'.
1046	 */
1047	if (!ctx->subsys_mask && !ctx->none && !ctx->name)
1048		ctx->all_ss = true;
1049
1050	if (ctx->all_ss) {
1051		/* Mutually exclusive option 'all' + subsystem name */
1052		if (ctx->subsys_mask)
1053			return invalfc(fc, "subsys name conflicts with all");
1054		/* 'all' => select all the subsystems */
1055		ctx->subsys_mask = enabled;
1056	}
1057
1058	/*
1059	 * We either have to specify by name or by subsystems. (So all
1060	 * empty hierarchies must have a name).
1061	 */
1062	if (!ctx->subsys_mask && !ctx->name)
1063		return invalfc(fc, "Need name or subsystem set");
1064
1065	/*
1066	 * Option noprefix was introduced just for backward compatibility
1067	 * with the old cpuset, so we allow noprefix only if mounting just
1068	 * the cpuset subsystem.
1069	 */
1070	if ((ctx->flags & CGRP_ROOT_NOPREFIX) && (ctx->subsys_mask & mask))
1071		return invalfc(fc, "noprefix used incorrectly");
1072
1073	/* Can't specify "none" and some subsystems */
1074	if (ctx->subsys_mask && ctx->none)
1075		return invalfc(fc, "none used incorrectly");
1076
1077	return 0;
1078}
1079
1080int cgroup1_reconfigure(struct fs_context *fc)
1081{
1082	struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
1083	struct kernfs_root *kf_root = kernfs_root_from_sb(fc->root->d_sb);
1084	struct cgroup_root *root = cgroup_root_from_kf(kf_root);
1085	int ret = 0;
1086	u16 added_mask, removed_mask;
1087
1088	cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
1089
1090	/* See what subsystems are wanted */
1091	ret = check_cgroupfs_options(fc);
1092	if (ret)
1093		goto out_unlock;
1094
1095	if (ctx->subsys_mask != root->subsys_mask || ctx->release_agent)
1096		pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
1097			task_tgid_nr(current), current->comm);
1098
1099	added_mask = ctx->subsys_mask & ~root->subsys_mask;
1100	removed_mask = root->subsys_mask & ~ctx->subsys_mask;
1101
1102	/* Don't allow flags or name to change at remount */
1103	if ((ctx->flags ^ root->flags) ||
1104	    (ctx->name && strcmp(ctx->name, root->name))) {
1105		errorfc(fc, "option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"",
1106		       ctx->flags, ctx->name ?: "", root->flags, root->name);
1107		ret = -EINVAL;
1108		goto out_unlock;
1109	}
1110
1111	/* remounting is not allowed for populated hierarchies */
1112	if (!list_empty(&root->cgrp.self.children)) {
1113		ret = -EBUSY;
1114		goto out_unlock;
1115	}
1116
1117	ret = rebind_subsystems(root, added_mask);
1118	if (ret)
1119		goto out_unlock;
1120
1121	WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask));
1122
1123	if (ctx->release_agent) {
1124		spin_lock(&release_agent_path_lock);
1125		strcpy(root->release_agent_path, ctx->release_agent);
1126		spin_unlock(&release_agent_path_lock);
1127	}
1128
1129	trace_cgroup_remount(root);
1130
1131 out_unlock:
1132	cgroup_unlock();
1133	return ret;
1134}
1135
1136struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
1137	.rename			= cgroup1_rename,
1138	.show_options		= cgroup1_show_options,
1139	.mkdir			= cgroup_mkdir,
1140	.rmdir			= cgroup_rmdir,
1141	.show_path		= cgroup_show_path,
1142};
1143
1144/*
1145 * The guts of cgroup1 mount - find or create cgroup_root to use.
1146 * Called with cgroup_mutex held; returns 0 on success, -E... on
1147 * error and positive - in case when the candidate is busy dying.
1148 * On success it stashes a reference to cgroup_root into given
1149 * cgroup_fs_context; that reference is *NOT* counting towards the
1150 * cgroup_root refcount.
1151 */
1152static int cgroup1_root_to_use(struct fs_context *fc)
1153{
1154	struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
1155	struct cgroup_root *root;
1156	struct cgroup_subsys *ss;
1157	int i, ret;
1158
1159	/* First find the desired set of subsystems */
1160	ret = check_cgroupfs_options(fc);
1161	if (ret)
1162		return ret;
1163
1164	/*
1165	 * Destruction of cgroup root is asynchronous, so subsystems may
1166	 * still be dying after the previous unmount.  Let's drain the
1167	 * dying subsystems.  We just need to ensure that the ones
1168	 * unmounted previously finish dying and don't care about new ones
1169	 * starting.  Testing ref liveliness is good enough.
1170	 */
1171	for_each_subsys(ss, i) {
1172		if (!(ctx->subsys_mask & (1 << i)) ||
1173		    ss->root == &cgrp_dfl_root)
1174			continue;
1175
1176		if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt))
1177			return 1;	/* restart */
1178		cgroup_put(&ss->root->cgrp);
1179	}
1180
1181	for_each_root(root) {
1182		bool name_match = false;
1183
1184		if (root == &cgrp_dfl_root)
1185			continue;
1186
1187		/*
1188		 * If we asked for a name then it must match.  Also, if
1189		 * name matches but sybsys_mask doesn't, we should fail.
1190		 * Remember whether name matched.
1191		 */
1192		if (ctx->name) {
1193			if (strcmp(ctx->name, root->name))
1194				continue;
1195			name_match = true;
1196		}
1197
1198		/*
1199		 * If we asked for subsystems (or explicitly for no
1200		 * subsystems) then they must match.
1201		 */
1202		if ((ctx->subsys_mask || ctx->none) &&
1203		    (ctx->subsys_mask != root->subsys_mask)) {
1204			if (!name_match)
1205				continue;
1206			return -EBUSY;
1207		}
1208
1209		if (root->flags ^ ctx->flags)
1210			pr_warn("new mount options do not match the existing superblock, will be ignored\n");
1211
1212		ctx->root = root;
1213		return 0;
1214	}
1215
1216	/*
1217	 * No such thing, create a new one.  name= matching without subsys
1218	 * specification is allowed for already existing hierarchies but we
1219	 * can't create new one without subsys specification.
1220	 */
1221	if (!ctx->subsys_mask && !ctx->none)
1222		return invalfc(fc, "No subsys list or none specified");
1223
1224	/* Hierarchies may only be created in the initial cgroup namespace. */
1225	if (ctx->ns != &init_cgroup_ns)
1226		return -EPERM;
1227
1228	root = kzalloc(sizeof(*root), GFP_KERNEL);
1229	if (!root)
1230		return -ENOMEM;
1231
1232	ctx->root = root;
1233	init_cgroup_root(ctx);
1234
1235	ret = cgroup_setup_root(root, ctx->subsys_mask);
1236	if (!ret)
1237		cgroup_favor_dynmods(root, ctx->flags & CGRP_ROOT_FAVOR_DYNMODS);
1238	else
1239		cgroup_free_root(root);
1240
1241	return ret;
1242}
1243
1244int cgroup1_get_tree(struct fs_context *fc)
1245{
1246	struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
1247	int ret;
1248
1249	/* Check if the caller has permission to mount. */
1250	if (!ns_capable(ctx->ns->user_ns, CAP_SYS_ADMIN))
1251		return -EPERM;
1252
1253	cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
1254
1255	ret = cgroup1_root_to_use(fc);
1256	if (!ret && !percpu_ref_tryget_live(&ctx->root->cgrp.self.refcnt))
1257		ret = 1;	/* restart */
1258
1259	cgroup_unlock();
1260
1261	if (!ret)
1262		ret = cgroup_do_get_tree(fc);
1263
1264	if (!ret && percpu_ref_is_dying(&ctx->root->cgrp.self.refcnt)) {
1265		fc_drop_locked(fc);
 
 
1266		ret = 1;
1267	}
1268
1269	if (unlikely(ret > 0)) {
1270		msleep(10);
1271		return restart_syscall();
1272	}
1273	return ret;
1274}
1275
1276/**
1277 * task_get_cgroup1 - Acquires the associated cgroup of a task within a
1278 * specific cgroup1 hierarchy. The cgroup1 hierarchy is identified by its
1279 * hierarchy ID.
1280 * @tsk: The target task
1281 * @hierarchy_id: The ID of a cgroup1 hierarchy
1282 *
1283 * On success, the cgroup is returned. On failure, ERR_PTR is returned.
1284 * We limit it to cgroup1 only.
1285 */
1286struct cgroup *task_get_cgroup1(struct task_struct *tsk, int hierarchy_id)
1287{
1288	struct cgroup *cgrp = ERR_PTR(-ENOENT);
1289	struct cgroup_root *root;
1290	unsigned long flags;
1291
1292	rcu_read_lock();
1293	for_each_root(root) {
1294		/* cgroup1 only*/
1295		if (root == &cgrp_dfl_root)
1296			continue;
1297		if (root->hierarchy_id != hierarchy_id)
1298			continue;
1299		spin_lock_irqsave(&css_set_lock, flags);
1300		cgrp = task_cgroup_from_root(tsk, root);
1301		if (!cgrp || !cgroup_tryget(cgrp))
1302			cgrp = ERR_PTR(-ENOENT);
1303		spin_unlock_irqrestore(&css_set_lock, flags);
1304		break;
1305	}
1306	rcu_read_unlock();
1307	return cgrp;
1308}
1309
1310static int __init cgroup1_wq_init(void)
1311{
1312	/*
1313	 * Used to destroy pidlists and separate to serve as flush domain.
1314	 * Cap @max_active to 1 too.
1315	 */
1316	cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
1317						    0, 1);
1318	BUG_ON(!cgroup_pidlist_destroy_wq);
1319	return 0;
1320}
1321core_initcall(cgroup1_wq_init);
1322
1323static int __init cgroup_no_v1(char *str)
1324{
1325	struct cgroup_subsys *ss;
1326	char *token;
1327	int i;
1328
1329	while ((token = strsep(&str, ",")) != NULL) {
1330		if (!*token)
1331			continue;
1332
1333		if (!strcmp(token, "all")) {
1334			cgroup_no_v1_mask = U16_MAX;
1335			continue;
1336		}
1337
1338		if (!strcmp(token, "named")) {
1339			cgroup_no_v1_named = true;
1340			continue;
1341		}
1342
1343		for_each_subsys(ss, i) {
1344			if (strcmp(token, ss->name) &&
1345			    strcmp(token, ss->legacy_name))
1346				continue;
1347
1348			cgroup_no_v1_mask |= 1 << i;
1349			break;
1350		}
1351	}
1352	return 1;
1353}
1354__setup("cgroup_no_v1=", cgroup_no_v1);