1 // SPDX-License-Identifier: GPL-2.0-only
2 #include "cgroup-internal.h"
4 #include <linux/ctype.h>
5 #include <linux/kmod.h>
6 #include <linux/sort.h>
7 #include <linux/delay.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>
19 #include <trace/events/cgroup.h>
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.
27 #define CGROUP_PIDLIST_DESTROY_DELAY HZ
29 /* Controllers blocked by the commandline in v1 */
30 static u16 cgroup_no_v1_mask;
32 /* disable named v1 mounts */
33 static bool cgroup_no_v1_named;
36 * pidlist destructions need to be flushed on cgroup destruction. Use a
37 * separate workqueue as flush domain.
39 static struct workqueue_struct *cgroup_pidlist_destroy_wq;
42 * Protects cgroup_subsys->release_agent_path. Modifying it also requires
43 * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock.
45 static DEFINE_SPINLOCK(release_agent_path_lock);
47 bool cgroup1_ssid_disabled(int ssid)
49 return cgroup_no_v1_mask & (1 << ssid);
53 * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
54 * @from: attach to all cgroups of a given task
55 * @tsk: the task to be attached
57 int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
59 struct cgroup_root *root;
62 mutex_lock(&cgroup_mutex);
63 percpu_down_write(&cgroup_threadgroup_rwsem);
65 struct cgroup *from_cgrp;
67 if (root == &cgrp_dfl_root)
70 spin_lock_irq(&css_set_lock);
71 from_cgrp = task_cgroup_from_root(from, root);
72 spin_unlock_irq(&css_set_lock);
74 retval = cgroup_attach_task(from_cgrp, tsk, false);
78 percpu_up_write(&cgroup_threadgroup_rwsem);
79 mutex_unlock(&cgroup_mutex);
83 EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
86 * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
87 * @to: cgroup to which the tasks will be moved
88 * @from: cgroup in which the tasks currently reside
90 * Locking rules between cgroup_post_fork() and the migration path
91 * guarantee that, if a task is forking while being migrated, the new child
92 * is guaranteed to be either visible in the source cgroup after the
93 * parent's migration is complete or put into the target cgroup. No task
94 * can slip out of migration through forking.
96 int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
98 DEFINE_CGROUP_MGCTX(mgctx);
99 struct cgrp_cset_link *link;
100 struct css_task_iter it;
101 struct task_struct *task;
104 if (cgroup_on_dfl(to))
107 ret = cgroup_migrate_vet_dst(to);
111 mutex_lock(&cgroup_mutex);
113 percpu_down_write(&cgroup_threadgroup_rwsem);
115 /* all tasks in @from are being moved, all csets are source */
116 spin_lock_irq(&css_set_lock);
117 list_for_each_entry(link, &from->cset_links, cset_link)
118 cgroup_migrate_add_src(link->cset, to, &mgctx);
119 spin_unlock_irq(&css_set_lock);
121 ret = cgroup_migrate_prepare_dst(&mgctx);
126 * Migrate tasks one-by-one until @from is empty. This fails iff
127 * ->can_attach() fails.
130 css_task_iter_start(&from->self, 0, &it);
133 task = css_task_iter_next(&it);
134 } while (task && (task->flags & PF_EXITING));
137 get_task_struct(task);
138 css_task_iter_end(&it);
141 ret = cgroup_migrate(task, false, &mgctx);
143 TRACE_CGROUP_PATH(transfer_tasks, to, task, false);
144 put_task_struct(task);
146 } while (task && !ret);
148 cgroup_migrate_finish(&mgctx);
149 percpu_up_write(&cgroup_threadgroup_rwsem);
150 mutex_unlock(&cgroup_mutex);
155 * Stuff for reading the 'tasks'/'procs' files.
157 * Reading this file can return large amounts of data if a cgroup has
158 * *lots* of attached tasks. So it may need several calls to read(),
159 * but we cannot guarantee that the information we produce is correct
160 * unless we produce it entirely atomically.
164 /* which pidlist file are we talking about? */
165 enum cgroup_filetype {
171 * A pidlist is a list of pids that virtually represents the contents of one
172 * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
173 * a pair (one each for procs, tasks) for each pid namespace that's relevant
176 struct cgroup_pidlist {
178 * used to find which pidlist is wanted. doesn't change as long as
179 * this particular list stays in the list.
181 struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
184 /* how many elements the above list has */
186 /* each of these stored in a list by its cgroup */
187 struct list_head links;
188 /* pointer to the cgroup we belong to, for list removal purposes */
189 struct cgroup *owner;
190 /* for delayed destruction */
191 struct delayed_work destroy_dwork;
195 * Used to destroy all pidlists lingering waiting for destroy timer. None
196 * should be left afterwards.
198 void cgroup1_pidlist_destroy_all(struct cgroup *cgrp)
200 struct cgroup_pidlist *l, *tmp_l;
202 mutex_lock(&cgrp->pidlist_mutex);
203 list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
204 mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
205 mutex_unlock(&cgrp->pidlist_mutex);
207 flush_workqueue(cgroup_pidlist_destroy_wq);
208 BUG_ON(!list_empty(&cgrp->pidlists));
211 static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
213 struct delayed_work *dwork = to_delayed_work(work);
214 struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
216 struct cgroup_pidlist *tofree = NULL;
218 mutex_lock(&l->owner->pidlist_mutex);
221 * Destroy iff we didn't get queued again. The state won't change
222 * as destroy_dwork can only be queued while locked.
224 if (!delayed_work_pending(dwork)) {
227 put_pid_ns(l->key.ns);
231 mutex_unlock(&l->owner->pidlist_mutex);
236 * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
237 * Returns the number of unique elements.
239 static int pidlist_uniq(pid_t *list, int length)
244 * we presume the 0th element is unique, so i starts at 1. trivial
245 * edge cases first; no work needs to be done for either
247 if (length == 0 || length == 1)
249 /* src and dest walk down the list; dest counts unique elements */
250 for (src = 1; src < length; src++) {
251 /* find next unique element */
252 while (list[src] == list[src-1]) {
257 /* dest always points to where the next unique element goes */
258 list[dest] = list[src];
266 * The two pid files - task and cgroup.procs - guaranteed that the result
267 * is sorted, which forced this whole pidlist fiasco. As pid order is
268 * different per namespace, each namespace needs differently sorted list,
269 * making it impossible to use, for example, single rbtree of member tasks
270 * sorted by task pointer. As pidlists can be fairly large, allocating one
271 * per open file is dangerous, so cgroup had to implement shared pool of
272 * pidlists keyed by cgroup and namespace.
274 static int cmppid(const void *a, const void *b)
276 return *(pid_t *)a - *(pid_t *)b;
279 static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
280 enum cgroup_filetype type)
282 struct cgroup_pidlist *l;
283 /* don't need task_nsproxy() if we're looking at ourself */
284 struct pid_namespace *ns = task_active_pid_ns(current);
286 lockdep_assert_held(&cgrp->pidlist_mutex);
288 list_for_each_entry(l, &cgrp->pidlists, links)
289 if (l->key.type == type && l->key.ns == ns)
295 * find the appropriate pidlist for our purpose (given procs vs tasks)
296 * returns with the lock on that pidlist already held, and takes care
297 * of the use count, or returns NULL with no locks held if we're out of
300 static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
301 enum cgroup_filetype type)
303 struct cgroup_pidlist *l;
305 lockdep_assert_held(&cgrp->pidlist_mutex);
307 l = cgroup_pidlist_find(cgrp, type);
311 /* entry not found; create a new one */
312 l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
316 INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
318 /* don't need task_nsproxy() if we're looking at ourself */
319 l->key.ns = get_pid_ns(task_active_pid_ns(current));
321 list_add(&l->links, &cgrp->pidlists);
326 * Load a cgroup's pidarray with either procs' tgids or tasks' pids
328 static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
329 struct cgroup_pidlist **lp)
333 int pid, n = 0; /* used for populating the array */
334 struct css_task_iter it;
335 struct task_struct *tsk;
336 struct cgroup_pidlist *l;
338 lockdep_assert_held(&cgrp->pidlist_mutex);
341 * If cgroup gets more users after we read count, we won't have
342 * enough space - tough. This race is indistinguishable to the
343 * caller from the case that the additional cgroup users didn't
344 * show up until sometime later on.
346 length = cgroup_task_count(cgrp);
347 array = kvmalloc_array(length, sizeof(pid_t), GFP_KERNEL);
350 /* now, populate the array */
351 css_task_iter_start(&cgrp->self, 0, &it);
352 while ((tsk = css_task_iter_next(&it))) {
353 if (unlikely(n == length))
355 /* get tgid or pid for procs or tasks file respectively */
356 if (type == CGROUP_FILE_PROCS)
357 pid = task_tgid_vnr(tsk);
359 pid = task_pid_vnr(tsk);
360 if (pid > 0) /* make sure to only use valid results */
363 css_task_iter_end(&it);
365 /* now sort & (if procs) strip out duplicates */
366 sort(array, length, sizeof(pid_t), cmppid, NULL);
367 if (type == CGROUP_FILE_PROCS)
368 length = pidlist_uniq(array, length);
370 l = cgroup_pidlist_find_create(cgrp, type);
376 /* store array, freeing old if necessary */
385 * seq_file methods for the tasks/procs files. The seq_file position is the
386 * next pid to display; the seq_file iterator is a pointer to the pid
387 * in the cgroup->l->list array.
390 static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
393 * Initially we receive a position value that corresponds to
394 * one more than the last pid shown (or 0 on the first call or
395 * after a seek to the start). Use a binary-search to find the
396 * next pid to display, if any
398 struct kernfs_open_file *of = s->private;
399 struct cgroup *cgrp = seq_css(s)->cgroup;
400 struct cgroup_pidlist *l;
401 enum cgroup_filetype type = seq_cft(s)->private;
402 int index = 0, pid = *pos;
405 mutex_lock(&cgrp->pidlist_mutex);
408 * !NULL @of->priv indicates that this isn't the first start()
409 * after open. If the matching pidlist is around, we can use that.
410 * Look for it. Note that @of->priv can't be used directly. It
411 * could already have been destroyed.
414 of->priv = cgroup_pidlist_find(cgrp, type);
417 * Either this is the first start() after open or the matching
418 * pidlist has been destroyed inbetween. Create a new one.
421 ret = pidlist_array_load(cgrp, type,
422 (struct cgroup_pidlist **)&of->priv);
431 while (index < end) {
432 int mid = (index + end) / 2;
433 if (l->list[mid] == pid) {
436 } else if (l->list[mid] <= pid)
442 /* If we're off the end of the array, we're done */
443 if (index >= l->length)
445 /* Update the abstract position to be the actual pid that we found */
446 iter = l->list + index;
451 static void cgroup_pidlist_stop(struct seq_file *s, void *v)
453 struct kernfs_open_file *of = s->private;
454 struct cgroup_pidlist *l = of->priv;
457 mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
458 CGROUP_PIDLIST_DESTROY_DELAY);
459 mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
462 static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
464 struct kernfs_open_file *of = s->private;
465 struct cgroup_pidlist *l = of->priv;
467 pid_t *end = l->list + l->length;
469 * Advance to the next pid in the array. If this goes off the
481 static int cgroup_pidlist_show(struct seq_file *s, void *v)
483 seq_printf(s, "%d\n", *(int *)v);
488 static ssize_t __cgroup1_procs_write(struct kernfs_open_file *of,
489 char *buf, size_t nbytes, loff_t off,
493 struct task_struct *task;
494 const struct cred *cred, *tcred;
498 cgrp = cgroup_kn_lock_live(of->kn, false);
502 task = cgroup_procs_write_start(buf, threadgroup, &locked);
503 ret = PTR_ERR_OR_ZERO(task);
508 * Even if we're attaching all tasks in the thread group, we only
509 * need to check permissions on one of them.
511 cred = current_cred();
512 tcred = get_task_cred(task);
513 if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
514 !uid_eq(cred->euid, tcred->uid) &&
515 !uid_eq(cred->euid, tcred->suid))
521 ret = cgroup_attach_task(cgrp, task, threadgroup);
524 cgroup_procs_write_finish(task, locked);
526 cgroup_kn_unlock(of->kn);
528 return ret ?: nbytes;
531 static ssize_t cgroup1_procs_write(struct kernfs_open_file *of,
532 char *buf, size_t nbytes, loff_t off)
534 return __cgroup1_procs_write(of, buf, nbytes, off, true);
537 static ssize_t cgroup1_tasks_write(struct kernfs_open_file *of,
538 char *buf, size_t nbytes, loff_t off)
540 return __cgroup1_procs_write(of, buf, nbytes, off, false);
543 static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
544 char *buf, size_t nbytes, loff_t off)
548 BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
550 cgrp = cgroup_kn_lock_live(of->kn, false);
553 spin_lock(&release_agent_path_lock);
554 strlcpy(cgrp->root->release_agent_path, strstrip(buf),
555 sizeof(cgrp->root->release_agent_path));
556 spin_unlock(&release_agent_path_lock);
557 cgroup_kn_unlock(of->kn);
561 static int cgroup_release_agent_show(struct seq_file *seq, void *v)
563 struct cgroup *cgrp = seq_css(seq)->cgroup;
565 spin_lock(&release_agent_path_lock);
566 seq_puts(seq, cgrp->root->release_agent_path);
567 spin_unlock(&release_agent_path_lock);
572 static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
574 seq_puts(seq, "0\n");
578 static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
581 return notify_on_release(css->cgroup);
584 static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
585 struct cftype *cft, u64 val)
588 set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
590 clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
594 static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
597 return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
600 static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
601 struct cftype *cft, u64 val)
604 set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
606 clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
610 /* cgroup core interface files for the legacy hierarchies */
611 struct cftype cgroup1_base_files[] = {
613 .name = "cgroup.procs",
614 .seq_start = cgroup_pidlist_start,
615 .seq_next = cgroup_pidlist_next,
616 .seq_stop = cgroup_pidlist_stop,
617 .seq_show = cgroup_pidlist_show,
618 .private = CGROUP_FILE_PROCS,
619 .write = cgroup1_procs_write,
622 .name = "cgroup.clone_children",
623 .read_u64 = cgroup_clone_children_read,
624 .write_u64 = cgroup_clone_children_write,
627 .name = "cgroup.sane_behavior",
628 .flags = CFTYPE_ONLY_ON_ROOT,
629 .seq_show = cgroup_sane_behavior_show,
633 .seq_start = cgroup_pidlist_start,
634 .seq_next = cgroup_pidlist_next,
635 .seq_stop = cgroup_pidlist_stop,
636 .seq_show = cgroup_pidlist_show,
637 .private = CGROUP_FILE_TASKS,
638 .write = cgroup1_tasks_write,
641 .name = "notify_on_release",
642 .read_u64 = cgroup_read_notify_on_release,
643 .write_u64 = cgroup_write_notify_on_release,
646 .name = "release_agent",
647 .flags = CFTYPE_ONLY_ON_ROOT,
648 .seq_show = cgroup_release_agent_show,
649 .write = cgroup_release_agent_write,
650 .max_write_len = PATH_MAX - 1,
655 /* Display information about each subsystem and each hierarchy */
656 int proc_cgroupstats_show(struct seq_file *m, void *v)
658 struct cgroup_subsys *ss;
661 seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
663 * ideally we don't want subsystems moving around while we do this.
664 * cgroup_mutex is also necessary to guarantee an atomic snapshot of
665 * subsys/hierarchy state.
667 mutex_lock(&cgroup_mutex);
669 for_each_subsys(ss, i)
670 seq_printf(m, "%s\t%d\t%d\t%d\n",
671 ss->legacy_name, ss->root->hierarchy_id,
672 atomic_read(&ss->root->nr_cgrps),
673 cgroup_ssid_enabled(i));
675 mutex_unlock(&cgroup_mutex);
680 * cgroupstats_build - build and fill cgroupstats
681 * @stats: cgroupstats to fill information into
682 * @dentry: A dentry entry belonging to the cgroup for which stats have
685 * Build and fill cgroupstats so that taskstats can export it to user
688 int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
690 struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
692 struct css_task_iter it;
693 struct task_struct *tsk;
695 /* it should be kernfs_node belonging to cgroupfs and is a directory */
696 if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
697 kernfs_type(kn) != KERNFS_DIR)
700 mutex_lock(&cgroup_mutex);
703 * We aren't being called from kernfs and there's no guarantee on
704 * @kn->priv's validity. For this and css_tryget_online_from_dir(),
705 * @kn->priv is RCU safe. Let's do the RCU dancing.
708 cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
709 if (!cgrp || cgroup_is_dead(cgrp)) {
711 mutex_unlock(&cgroup_mutex);
716 css_task_iter_start(&cgrp->self, 0, &it);
717 while ((tsk = css_task_iter_next(&it))) {
718 switch (tsk->state) {
722 case TASK_INTERRUPTIBLE:
723 stats->nr_sleeping++;
725 case TASK_UNINTERRUPTIBLE:
726 stats->nr_uninterruptible++;
732 if (delayacct_is_task_waiting_on_io(tsk))
737 css_task_iter_end(&it);
739 mutex_unlock(&cgroup_mutex);
743 void cgroup1_check_for_release(struct cgroup *cgrp)
745 if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
746 !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
747 schedule_work(&cgrp->release_agent_work);
751 * Notify userspace when a cgroup is released, by running the
752 * configured release agent with the name of the cgroup (path
753 * relative to the root of cgroup file system) as the argument.
755 * Most likely, this user command will try to rmdir this cgroup.
757 * This races with the possibility that some other task will be
758 * attached to this cgroup before it is removed, or that some other
759 * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
760 * The presumed 'rmdir' will fail quietly if this cgroup is no longer
761 * unused, and this cgroup will be reprieved from its death sentence,
762 * to continue to serve a useful existence. Next time it's released,
763 * we will get notified again, if it still has 'notify_on_release' set.
765 * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
766 * means only wait until the task is successfully execve()'d. The
767 * separate release agent task is forked by call_usermodehelper(),
768 * then control in this thread returns here, without waiting for the
769 * release agent task. We don't bother to wait because the caller of
770 * this routine has no use for the exit status of the release agent
771 * task, so no sense holding our caller up for that.
773 void cgroup1_release_agent(struct work_struct *work)
775 struct cgroup *cgrp =
776 container_of(work, struct cgroup, release_agent_work);
777 char *pathbuf = NULL, *agentbuf = NULL;
778 char *argv[3], *envp[3];
781 mutex_lock(&cgroup_mutex);
783 pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
784 agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
785 if (!pathbuf || !agentbuf)
788 spin_lock_irq(&css_set_lock);
789 ret = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
790 spin_unlock_irq(&css_set_lock);
791 if (ret < 0 || ret >= PATH_MAX)
798 /* minimal command environment */
800 envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
803 mutex_unlock(&cgroup_mutex);
804 call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
807 mutex_unlock(&cgroup_mutex);
814 * cgroup_rename - Only allow simple rename of directories in place.
816 static int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
817 const char *new_name_str)
819 struct cgroup *cgrp = kn->priv;
822 if (kernfs_type(kn) != KERNFS_DIR)
824 if (kn->parent != new_parent)
828 * We're gonna grab cgroup_mutex which nests outside kernfs
829 * active_ref. kernfs_rename() doesn't require active_ref
830 * protection. Break them before grabbing cgroup_mutex.
832 kernfs_break_active_protection(new_parent);
833 kernfs_break_active_protection(kn);
835 mutex_lock(&cgroup_mutex);
837 ret = kernfs_rename(kn, new_parent, new_name_str);
839 TRACE_CGROUP_PATH(rename, cgrp);
841 mutex_unlock(&cgroup_mutex);
843 kernfs_unbreak_active_protection(kn);
844 kernfs_unbreak_active_protection(new_parent);
848 static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
850 struct cgroup_root *root = cgroup_root_from_kf(kf_root);
851 struct cgroup_subsys *ss;
854 for_each_subsys(ss, ssid)
855 if (root->subsys_mask & (1 << ssid))
856 seq_show_option(seq, ss->legacy_name, NULL);
857 if (root->flags & CGRP_ROOT_NOPREFIX)
858 seq_puts(seq, ",noprefix");
859 if (root->flags & CGRP_ROOT_XATTR)
860 seq_puts(seq, ",xattr");
861 if (root->flags & CGRP_ROOT_CPUSET_V2_MODE)
862 seq_puts(seq, ",cpuset_v2_mode");
864 spin_lock(&release_agent_path_lock);
865 if (strlen(root->release_agent_path))
866 seq_show_option(seq, "release_agent",
867 root->release_agent_path);
868 spin_unlock(&release_agent_path_lock);
870 if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
871 seq_puts(seq, ",clone_children");
872 if (strlen(root->name))
873 seq_show_option(seq, "name", root->name);
888 const struct fs_parameter_spec cgroup1_fs_parameters[] = {
889 fsparam_flag ("all", Opt_all),
890 fsparam_flag ("clone_children", Opt_clone_children),
891 fsparam_flag ("cpuset_v2_mode", Opt_cpuset_v2_mode),
892 fsparam_string("name", Opt_name),
893 fsparam_flag ("none", Opt_none),
894 fsparam_flag ("noprefix", Opt_noprefix),
895 fsparam_string("release_agent", Opt_release_agent),
896 fsparam_flag ("xattr", Opt_xattr),
900 int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param)
902 struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
903 struct cgroup_subsys *ss;
904 struct fs_parse_result result;
907 opt = fs_parse(fc, cgroup1_fs_parameters, param, &result);
908 if (opt == -ENOPARAM) {
909 if (strcmp(param->key, "source") == 0) {
910 fc->source = param->string;
911 param->string = NULL;
914 for_each_subsys(ss, i) {
915 if (strcmp(param->key, ss->legacy_name))
917 ctx->subsys_mask |= (1 << i);
920 return invalfc(fc, "Unknown subsys name '%s'", param->key);
927 /* Explicitly have no subsystems */
934 ctx->flags |= CGRP_ROOT_NOPREFIX;
936 case Opt_clone_children:
937 ctx->cpuset_clone_children = true;
939 case Opt_cpuset_v2_mode:
940 ctx->flags |= CGRP_ROOT_CPUSET_V2_MODE;
943 ctx->flags |= CGRP_ROOT_XATTR;
945 case Opt_release_agent:
946 /* Specifying two release agents is forbidden */
947 if (ctx->release_agent)
948 return invalfc(fc, "release_agent respecified");
949 ctx->release_agent = param->string;
950 param->string = NULL;
953 /* blocked by boot param? */
954 if (cgroup_no_v1_named)
956 /* Can't specify an empty name */
958 return invalfc(fc, "Empty name");
959 if (param->size > MAX_CGROUP_ROOT_NAMELEN - 1)
960 return invalfc(fc, "Name too long");
961 /* Must match [\w.-]+ */
962 for (i = 0; i < param->size; i++) {
963 char c = param->string[i];
966 if ((c == '.') || (c == '-') || (c == '_'))
968 return invalfc(fc, "Invalid name");
970 /* Specifying two names is forbidden */
972 return invalfc(fc, "name respecified");
973 ctx->name = param->string;
974 param->string = NULL;
980 static int check_cgroupfs_options(struct fs_context *fc)
982 struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
985 struct cgroup_subsys *ss;
988 #ifdef CONFIG_CPUSETS
989 mask = ~((u16)1 << cpuset_cgrp_id);
991 for_each_subsys(ss, i)
992 if (cgroup_ssid_enabled(i) && !cgroup1_ssid_disabled(i))
995 ctx->subsys_mask &= enabled;
998 * In absense of 'none', 'name=' or subsystem name options,
999 * let's default to 'all'.
1001 if (!ctx->subsys_mask && !ctx->none && !ctx->name)
1005 /* Mutually exclusive option 'all' + subsystem name */
1006 if (ctx->subsys_mask)
1007 return invalfc(fc, "subsys name conflicts with all");
1008 /* 'all' => select all the subsystems */
1009 ctx->subsys_mask = enabled;
1013 * We either have to specify by name or by subsystems. (So all
1014 * empty hierarchies must have a name).
1016 if (!ctx->subsys_mask && !ctx->name)
1017 return invalfc(fc, "Need name or subsystem set");
1020 * Option noprefix was introduced just for backward compatibility
1021 * with the old cpuset, so we allow noprefix only if mounting just
1022 * the cpuset subsystem.
1024 if ((ctx->flags & CGRP_ROOT_NOPREFIX) && (ctx->subsys_mask & mask))
1025 return invalfc(fc, "noprefix used incorrectly");
1027 /* Can't specify "none" and some subsystems */
1028 if (ctx->subsys_mask && ctx->none)
1029 return invalfc(fc, "none used incorrectly");
1034 int cgroup1_reconfigure(struct fs_context *fc)
1036 struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
1037 struct kernfs_root *kf_root = kernfs_root_from_sb(fc->root->d_sb);
1038 struct cgroup_root *root = cgroup_root_from_kf(kf_root);
1040 u16 added_mask, removed_mask;
1042 cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
1044 /* See what subsystems are wanted */
1045 ret = check_cgroupfs_options(fc);
1049 if (ctx->subsys_mask != root->subsys_mask || ctx->release_agent)
1050 pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
1051 task_tgid_nr(current), current->comm);
1053 added_mask = ctx->subsys_mask & ~root->subsys_mask;
1054 removed_mask = root->subsys_mask & ~ctx->subsys_mask;
1056 /* Don't allow flags or name to change at remount */
1057 if ((ctx->flags ^ root->flags) ||
1058 (ctx->name && strcmp(ctx->name, root->name))) {
1059 errorfc(fc, "option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"",
1060 ctx->flags, ctx->name ?: "", root->flags, root->name);
1065 /* remounting is not allowed for populated hierarchies */
1066 if (!list_empty(&root->cgrp.self.children)) {
1071 ret = rebind_subsystems(root, added_mask);
1075 WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask));
1077 if (ctx->release_agent) {
1078 spin_lock(&release_agent_path_lock);
1079 strcpy(root->release_agent_path, ctx->release_agent);
1080 spin_unlock(&release_agent_path_lock);
1083 trace_cgroup_remount(root);
1086 mutex_unlock(&cgroup_mutex);
1090 struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
1091 .rename = cgroup1_rename,
1092 .show_options = cgroup1_show_options,
1093 .mkdir = cgroup_mkdir,
1094 .rmdir = cgroup_rmdir,
1095 .show_path = cgroup_show_path,
1099 * The guts of cgroup1 mount - find or create cgroup_root to use.
1100 * Called with cgroup_mutex held; returns 0 on success, -E... on
1101 * error and positive - in case when the candidate is busy dying.
1102 * On success it stashes a reference to cgroup_root into given
1103 * cgroup_fs_context; that reference is *NOT* counting towards the
1104 * cgroup_root refcount.
1106 static int cgroup1_root_to_use(struct fs_context *fc)
1108 struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
1109 struct cgroup_root *root;
1110 struct cgroup_subsys *ss;
1113 /* First find the desired set of subsystems */
1114 ret = check_cgroupfs_options(fc);
1119 * Destruction of cgroup root is asynchronous, so subsystems may
1120 * still be dying after the previous unmount. Let's drain the
1121 * dying subsystems. We just need to ensure that the ones
1122 * unmounted previously finish dying and don't care about new ones
1123 * starting. Testing ref liveliness is good enough.
1125 for_each_subsys(ss, i) {
1126 if (!(ctx->subsys_mask & (1 << i)) ||
1127 ss->root == &cgrp_dfl_root)
1130 if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt))
1131 return 1; /* restart */
1132 cgroup_put(&ss->root->cgrp);
1135 for_each_root(root) {
1136 bool name_match = false;
1138 if (root == &cgrp_dfl_root)
1142 * If we asked for a name then it must match. Also, if
1143 * name matches but sybsys_mask doesn't, we should fail.
1144 * Remember whether name matched.
1147 if (strcmp(ctx->name, root->name))
1153 * If we asked for subsystems (or explicitly for no
1154 * subsystems) then they must match.
1156 if ((ctx->subsys_mask || ctx->none) &&
1157 (ctx->subsys_mask != root->subsys_mask)) {
1163 if (root->flags ^ ctx->flags)
1164 pr_warn("new mount options do not match the existing superblock, will be ignored\n");
1171 * No such thing, create a new one. name= matching without subsys
1172 * specification is allowed for already existing hierarchies but we
1173 * can't create new one without subsys specification.
1175 if (!ctx->subsys_mask && !ctx->none)
1176 return invalfc(fc, "No subsys list or none specified");
1178 /* Hierarchies may only be created in the initial cgroup namespace. */
1179 if (ctx->ns != &init_cgroup_ns)
1182 root = kzalloc(sizeof(*root), GFP_KERNEL);
1187 init_cgroup_root(ctx);
1189 ret = cgroup_setup_root(root, ctx->subsys_mask);
1191 cgroup_free_root(root);
1195 int cgroup1_get_tree(struct fs_context *fc)
1197 struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
1200 /* Check if the caller has permission to mount. */
1201 if (!ns_capable(ctx->ns->user_ns, CAP_SYS_ADMIN))
1204 cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
1206 ret = cgroup1_root_to_use(fc);
1207 if (!ret && !percpu_ref_tryget_live(&ctx->root->cgrp.self.refcnt))
1208 ret = 1; /* restart */
1210 mutex_unlock(&cgroup_mutex);
1213 ret = cgroup_do_get_tree(fc);
1215 if (!ret && percpu_ref_is_dying(&ctx->root->cgrp.self.refcnt)) {
1216 struct super_block *sb = fc->root->d_sb;
1218 deactivate_locked_super(sb);
1222 if (unlikely(ret > 0)) {
1224 return restart_syscall();
1229 static int __init cgroup1_wq_init(void)
1232 * Used to destroy pidlists and separate to serve as flush domain.
1233 * Cap @max_active to 1 too.
1235 cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
1237 BUG_ON(!cgroup_pidlist_destroy_wq);
1240 core_initcall(cgroup1_wq_init);
1242 static int __init cgroup_no_v1(char *str)
1244 struct cgroup_subsys *ss;
1248 while ((token = strsep(&str, ",")) != NULL) {
1252 if (!strcmp(token, "all")) {
1253 cgroup_no_v1_mask = U16_MAX;
1257 if (!strcmp(token, "named")) {
1258 cgroup_no_v1_named = true;
1262 for_each_subsys(ss, i) {
1263 if (strcmp(token, ss->name) &&
1264 strcmp(token, ss->legacy_name))
1267 cgroup_no_v1_mask |= 1 << i;
1272 __setup("cgroup_no_v1=", cgroup_no_v1);