![Tejun Heo](/assets/img/avatar_default.png)
cgrp->root->release_agent_path is protected by both cgroup_mutex and release_agent_path_lock and readers can hold either one. The dual-locking scheme was introduced while breaking a locking dependency issue around cgroup_mutex but doesn't make sense anymore given that the only remaining reader which uses cgroup_mutex is cgroup1_releaes_agent(). This patch updates cgroup1_release_agent() to use release_agent_path_lock so that release_agent_path is always protected only by release_agent_path_lock. While at it, convert strlen() based empty string checks to direct tests on the first character as suggested by Linus. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org>
1274 lines
33 KiB
C
1274 lines
33 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include "cgroup-internal.h"
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#include <linux/ctype.h>
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#include <linux/kmod.h>
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#include <linux/sort.h>
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#include <linux/delay.h>
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#include <linux/mm.h>
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#include <linux/sched/signal.h>
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#include <linux/sched/task.h>
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#include <linux/magic.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <linux/delayacct.h>
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#include <linux/pid_namespace.h>
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#include <linux/cgroupstats.h>
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#include <linux/fs_parser.h>
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#include <trace/events/cgroup.h>
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/*
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* pidlists linger the following amount before being destroyed. The goal
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* is avoiding frequent destruction in the middle of consecutive read calls
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* Expiring in the middle is a performance problem not a correctness one.
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* 1 sec should be enough.
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*/
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#define CGROUP_PIDLIST_DESTROY_DELAY HZ
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/* Controllers blocked by the commandline in v1 */
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static u16 cgroup_no_v1_mask;
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/* disable named v1 mounts */
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static bool cgroup_no_v1_named;
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/*
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* pidlist destructions need to be flushed on cgroup destruction. Use a
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* separate workqueue as flush domain.
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*/
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static struct workqueue_struct *cgroup_pidlist_destroy_wq;
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/* protects cgroup_subsys->release_agent_path */
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static DEFINE_SPINLOCK(release_agent_path_lock);
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bool cgroup1_ssid_disabled(int ssid)
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{
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return cgroup_no_v1_mask & (1 << ssid);
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}
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/**
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* cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
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* @from: attach to all cgroups of a given task
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* @tsk: the task to be attached
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*/
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int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
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{
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struct cgroup_root *root;
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int retval = 0;
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mutex_lock(&cgroup_mutex);
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percpu_down_write(&cgroup_threadgroup_rwsem);
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for_each_root(root) {
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struct cgroup *from_cgrp;
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if (root == &cgrp_dfl_root)
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continue;
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spin_lock_irq(&css_set_lock);
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from_cgrp = task_cgroup_from_root(from, root);
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spin_unlock_irq(&css_set_lock);
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retval = cgroup_attach_task(from_cgrp, tsk, false);
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if (retval)
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break;
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}
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percpu_up_write(&cgroup_threadgroup_rwsem);
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mutex_unlock(&cgroup_mutex);
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return retval;
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}
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EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
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/**
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* cgroup_trasnsfer_tasks - move tasks from one cgroup to another
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* @to: cgroup to which the tasks will be moved
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* @from: cgroup in which the tasks currently reside
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*
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* Locking rules between cgroup_post_fork() and the migration path
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* guarantee that, if a task is forking while being migrated, the new child
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* is guaranteed to be either visible in the source cgroup after the
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* parent's migration is complete or put into the target cgroup. No task
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* can slip out of migration through forking.
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*/
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int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
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{
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DEFINE_CGROUP_MGCTX(mgctx);
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struct cgrp_cset_link *link;
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struct css_task_iter it;
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struct task_struct *task;
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int ret;
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if (cgroup_on_dfl(to))
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return -EINVAL;
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ret = cgroup_migrate_vet_dst(to);
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if (ret)
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return ret;
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mutex_lock(&cgroup_mutex);
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percpu_down_write(&cgroup_threadgroup_rwsem);
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/* all tasks in @from are being moved, all csets are source */
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spin_lock_irq(&css_set_lock);
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list_for_each_entry(link, &from->cset_links, cset_link)
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cgroup_migrate_add_src(link->cset, to, &mgctx);
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spin_unlock_irq(&css_set_lock);
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ret = cgroup_migrate_prepare_dst(&mgctx);
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if (ret)
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goto out_err;
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/*
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* Migrate tasks one-by-one until @from is empty. This fails iff
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* ->can_attach() fails.
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*/
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do {
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css_task_iter_start(&from->self, 0, &it);
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do {
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task = css_task_iter_next(&it);
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} while (task && (task->flags & PF_EXITING));
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if (task)
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get_task_struct(task);
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css_task_iter_end(&it);
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if (task) {
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ret = cgroup_migrate(task, false, &mgctx);
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if (!ret)
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TRACE_CGROUP_PATH(transfer_tasks, to, task, false);
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put_task_struct(task);
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}
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} while (task && !ret);
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out_err:
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cgroup_migrate_finish(&mgctx);
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percpu_up_write(&cgroup_threadgroup_rwsem);
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mutex_unlock(&cgroup_mutex);
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return ret;
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}
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/*
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* Stuff for reading the 'tasks'/'procs' files.
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*
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* Reading this file can return large amounts of data if a cgroup has
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* *lots* of attached tasks. So it may need several calls to read(),
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* but we cannot guarantee that the information we produce is correct
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* unless we produce it entirely atomically.
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*
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*/
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/* which pidlist file are we talking about? */
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enum cgroup_filetype {
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CGROUP_FILE_PROCS,
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CGROUP_FILE_TASKS,
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};
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/*
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* A pidlist is a list of pids that virtually represents the contents of one
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* of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
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* a pair (one each for procs, tasks) for each pid namespace that's relevant
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* to the cgroup.
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*/
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struct cgroup_pidlist {
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/*
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* used to find which pidlist is wanted. doesn't change as long as
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* this particular list stays in the list.
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*/
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struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
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/* array of xids */
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pid_t *list;
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/* how many elements the above list has */
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int length;
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/* each of these stored in a list by its cgroup */
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struct list_head links;
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/* pointer to the cgroup we belong to, for list removal purposes */
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struct cgroup *owner;
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/* for delayed destruction */
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struct delayed_work destroy_dwork;
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};
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/*
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* Used to destroy all pidlists lingering waiting for destroy timer. None
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* should be left afterwards.
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*/
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void cgroup1_pidlist_destroy_all(struct cgroup *cgrp)
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{
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struct cgroup_pidlist *l, *tmp_l;
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mutex_lock(&cgrp->pidlist_mutex);
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list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
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mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
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mutex_unlock(&cgrp->pidlist_mutex);
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flush_workqueue(cgroup_pidlist_destroy_wq);
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BUG_ON(!list_empty(&cgrp->pidlists));
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}
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static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
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{
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struct delayed_work *dwork = to_delayed_work(work);
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struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
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destroy_dwork);
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struct cgroup_pidlist *tofree = NULL;
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mutex_lock(&l->owner->pidlist_mutex);
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/*
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* Destroy iff we didn't get queued again. The state won't change
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* as destroy_dwork can only be queued while locked.
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*/
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if (!delayed_work_pending(dwork)) {
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list_del(&l->links);
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kvfree(l->list);
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put_pid_ns(l->key.ns);
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tofree = l;
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}
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mutex_unlock(&l->owner->pidlist_mutex);
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kfree(tofree);
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}
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/*
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* pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
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* Returns the number of unique elements.
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*/
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static int pidlist_uniq(pid_t *list, int length)
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{
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int src, dest = 1;
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/*
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* we presume the 0th element is unique, so i starts at 1. trivial
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* edge cases first; no work needs to be done for either
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*/
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if (length == 0 || length == 1)
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return length;
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/* src and dest walk down the list; dest counts unique elements */
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for (src = 1; src < length; src++) {
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/* find next unique element */
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while (list[src] == list[src-1]) {
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src++;
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if (src == length)
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goto after;
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}
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/* dest always points to where the next unique element goes */
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list[dest] = list[src];
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dest++;
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}
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after:
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return dest;
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}
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/*
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* The two pid files - task and cgroup.procs - guaranteed that the result
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* is sorted, which forced this whole pidlist fiasco. As pid order is
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* different per namespace, each namespace needs differently sorted list,
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* making it impossible to use, for example, single rbtree of member tasks
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* sorted by task pointer. As pidlists can be fairly large, allocating one
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* per open file is dangerous, so cgroup had to implement shared pool of
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* pidlists keyed by cgroup and namespace.
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*/
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static int cmppid(const void *a, const void *b)
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{
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return *(pid_t *)a - *(pid_t *)b;
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}
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static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
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enum cgroup_filetype type)
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{
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struct cgroup_pidlist *l;
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/* don't need task_nsproxy() if we're looking at ourself */
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struct pid_namespace *ns = task_active_pid_ns(current);
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lockdep_assert_held(&cgrp->pidlist_mutex);
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list_for_each_entry(l, &cgrp->pidlists, links)
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if (l->key.type == type && l->key.ns == ns)
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return l;
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return NULL;
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}
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/*
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* find the appropriate pidlist for our purpose (given procs vs tasks)
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* returns with the lock on that pidlist already held, and takes care
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* of the use count, or returns NULL with no locks held if we're out of
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* memory.
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*/
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static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
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enum cgroup_filetype type)
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{
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struct cgroup_pidlist *l;
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lockdep_assert_held(&cgrp->pidlist_mutex);
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l = cgroup_pidlist_find(cgrp, type);
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if (l)
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return l;
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/* entry not found; create a new one */
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l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
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if (!l)
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return l;
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INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
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l->key.type = type;
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/* don't need task_nsproxy() if we're looking at ourself */
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l->key.ns = get_pid_ns(task_active_pid_ns(current));
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l->owner = cgrp;
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list_add(&l->links, &cgrp->pidlists);
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return l;
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}
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/*
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* Load a cgroup's pidarray with either procs' tgids or tasks' pids
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*/
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static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
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struct cgroup_pidlist **lp)
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{
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pid_t *array;
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int length;
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int pid, n = 0; /* used for populating the array */
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struct css_task_iter it;
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struct task_struct *tsk;
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struct cgroup_pidlist *l;
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lockdep_assert_held(&cgrp->pidlist_mutex);
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/*
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* If cgroup gets more users after we read count, we won't have
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* enough space - tough. This race is indistinguishable to the
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* caller from the case that the additional cgroup users didn't
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* show up until sometime later on.
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*/
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length = cgroup_task_count(cgrp);
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array = kvmalloc_array(length, sizeof(pid_t), GFP_KERNEL);
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if (!array)
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return -ENOMEM;
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/* now, populate the array */
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css_task_iter_start(&cgrp->self, 0, &it);
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while ((tsk = css_task_iter_next(&it))) {
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if (unlikely(n == length))
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break;
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/* get tgid or pid for procs or tasks file respectively */
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if (type == CGROUP_FILE_PROCS)
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pid = task_tgid_vnr(tsk);
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else
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pid = task_pid_vnr(tsk);
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if (pid > 0) /* make sure to only use valid results */
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array[n++] = pid;
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}
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css_task_iter_end(&it);
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length = n;
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/* now sort & (if procs) strip out duplicates */
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sort(array, length, sizeof(pid_t), cmppid, NULL);
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if (type == CGROUP_FILE_PROCS)
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length = pidlist_uniq(array, length);
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l = cgroup_pidlist_find_create(cgrp, type);
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if (!l) {
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kvfree(array);
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return -ENOMEM;
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}
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/* store array, freeing old if necessary */
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kvfree(l->list);
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l->list = array;
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l->length = length;
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*lp = l;
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return 0;
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}
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/*
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* seq_file methods for the tasks/procs files. The seq_file position is the
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* next pid to display; the seq_file iterator is a pointer to the pid
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* in the cgroup->l->list array.
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*/
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static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
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{
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/*
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* Initially we receive a position value that corresponds to
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* one more than the last pid shown (or 0 on the first call or
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* after a seek to the start). Use a binary-search to find the
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* next pid to display, if any
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*/
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struct kernfs_open_file *of = s->private;
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struct cgroup *cgrp = seq_css(s)->cgroup;
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struct cgroup_pidlist *l;
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enum cgroup_filetype type = seq_cft(s)->private;
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int index = 0, pid = *pos;
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int *iter, ret;
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mutex_lock(&cgrp->pidlist_mutex);
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/*
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* !NULL @of->priv indicates that this isn't the first start()
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* after open. If the matching pidlist is around, we can use that.
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* Look for it. Note that @of->priv can't be used directly. It
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* could already have been destroyed.
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*/
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if (of->priv)
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of->priv = cgroup_pidlist_find(cgrp, type);
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/*
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* Either this is the first start() after open or the matching
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* pidlist has been destroyed inbetween. Create a new one.
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*/
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if (!of->priv) {
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ret = pidlist_array_load(cgrp, type,
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(struct cgroup_pidlist **)&of->priv);
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if (ret)
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return ERR_PTR(ret);
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}
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l = of->priv;
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if (pid) {
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int end = l->length;
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while (index < end) {
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int mid = (index + end) / 2;
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if (l->list[mid] == pid) {
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index = mid;
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break;
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} else if (l->list[mid] <= pid)
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index = mid + 1;
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else
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end = mid;
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}
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}
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/* If we're off the end of the array, we're done */
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if (index >= l->length)
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return NULL;
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/* Update the abstract position to be the actual pid that we found */
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iter = l->list + index;
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*pos = *iter;
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return iter;
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}
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|
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static void cgroup_pidlist_stop(struct seq_file *s, void *v)
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{
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struct kernfs_open_file *of = s->private;
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struct cgroup_pidlist *l = of->priv;
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if (l)
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mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
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CGROUP_PIDLIST_DESTROY_DELAY);
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mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
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}
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static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
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{
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struct kernfs_open_file *of = s->private;
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struct cgroup_pidlist *l = of->priv;
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pid_t *p = v;
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pid_t *end = l->list + l->length;
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/*
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* Advance to the next pid in the array. If this goes off the
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* end, we're done
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*/
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p++;
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if (p >= end) {
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(*pos)++;
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return NULL;
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} else {
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*pos = *p;
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return p;
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}
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}
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static int cgroup_pidlist_show(struct seq_file *s, void *v)
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{
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seq_printf(s, "%d\n", *(int *)v);
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return 0;
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}
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static ssize_t __cgroup1_procs_write(struct kernfs_open_file *of,
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char *buf, size_t nbytes, loff_t off,
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bool threadgroup)
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{
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struct cgroup *cgrp;
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struct task_struct *task;
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const struct cred *cred, *tcred;
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ssize_t ret;
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bool locked;
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cgrp = cgroup_kn_lock_live(of->kn, false);
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if (!cgrp)
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return -ENODEV;
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task = cgroup_procs_write_start(buf, threadgroup, &locked);
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ret = PTR_ERR_OR_ZERO(task);
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if (ret)
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goto out_unlock;
|
|
|
|
/*
|
|
* Even if we're attaching all tasks in the thread group, we only
|
|
* need to check permissions on one of them.
|
|
*/
|
|
cred = current_cred();
|
|
tcred = get_task_cred(task);
|
|
if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
|
|
!uid_eq(cred->euid, tcred->uid) &&
|
|
!uid_eq(cred->euid, tcred->suid))
|
|
ret = -EACCES;
|
|
put_cred(tcred);
|
|
if (ret)
|
|
goto out_finish;
|
|
|
|
ret = cgroup_attach_task(cgrp, task, threadgroup);
|
|
|
|
out_finish:
|
|
cgroup_procs_write_finish(task, locked);
|
|
out_unlock:
|
|
cgroup_kn_unlock(of->kn);
|
|
|
|
return ret ?: nbytes;
|
|
}
|
|
|
|
static ssize_t cgroup1_procs_write(struct kernfs_open_file *of,
|
|
char *buf, size_t nbytes, loff_t off)
|
|
{
|
|
return __cgroup1_procs_write(of, buf, nbytes, off, true);
|
|
}
|
|
|
|
static ssize_t cgroup1_tasks_write(struct kernfs_open_file *of,
|
|
char *buf, size_t nbytes, loff_t off)
|
|
{
|
|
return __cgroup1_procs_write(of, buf, nbytes, off, false);
|
|
}
|
|
|
|
static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
|
|
char *buf, size_t nbytes, loff_t off)
|
|
{
|
|
struct cgroup *cgrp;
|
|
|
|
BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
|
|
|
|
cgrp = cgroup_kn_lock_live(of->kn, false);
|
|
if (!cgrp)
|
|
return -ENODEV;
|
|
spin_lock(&release_agent_path_lock);
|
|
strlcpy(cgrp->root->release_agent_path, strstrip(buf),
|
|
sizeof(cgrp->root->release_agent_path));
|
|
spin_unlock(&release_agent_path_lock);
|
|
cgroup_kn_unlock(of->kn);
|
|
return nbytes;
|
|
}
|
|
|
|
static int cgroup_release_agent_show(struct seq_file *seq, void *v)
|
|
{
|
|
struct cgroup *cgrp = seq_css(seq)->cgroup;
|
|
|
|
spin_lock(&release_agent_path_lock);
|
|
seq_puts(seq, cgrp->root->release_agent_path);
|
|
spin_unlock(&release_agent_path_lock);
|
|
seq_putc(seq, '\n');
|
|
return 0;
|
|
}
|
|
|
|
static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
|
|
{
|
|
seq_puts(seq, "0\n");
|
|
return 0;
|
|
}
|
|
|
|
static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
return notify_on_release(css->cgroup);
|
|
}
|
|
|
|
static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
|
|
struct cftype *cft, u64 val)
|
|
{
|
|
if (val)
|
|
set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
|
|
else
|
|
clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
|
|
return 0;
|
|
}
|
|
|
|
static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
|
|
struct cftype *cft)
|
|
{
|
|
return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
|
}
|
|
|
|
static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
|
|
struct cftype *cft, u64 val)
|
|
{
|
|
if (val)
|
|
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
|
else
|
|
clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
|
|
return 0;
|
|
}
|
|
|
|
/* cgroup core interface files for the legacy hierarchies */
|
|
struct cftype cgroup1_base_files[] = {
|
|
{
|
|
.name = "cgroup.procs",
|
|
.seq_start = cgroup_pidlist_start,
|
|
.seq_next = cgroup_pidlist_next,
|
|
.seq_stop = cgroup_pidlist_stop,
|
|
.seq_show = cgroup_pidlist_show,
|
|
.private = CGROUP_FILE_PROCS,
|
|
.write = cgroup1_procs_write,
|
|
},
|
|
{
|
|
.name = "cgroup.clone_children",
|
|
.read_u64 = cgroup_clone_children_read,
|
|
.write_u64 = cgroup_clone_children_write,
|
|
},
|
|
{
|
|
.name = "cgroup.sane_behavior",
|
|
.flags = CFTYPE_ONLY_ON_ROOT,
|
|
.seq_show = cgroup_sane_behavior_show,
|
|
},
|
|
{
|
|
.name = "tasks",
|
|
.seq_start = cgroup_pidlist_start,
|
|
.seq_next = cgroup_pidlist_next,
|
|
.seq_stop = cgroup_pidlist_stop,
|
|
.seq_show = cgroup_pidlist_show,
|
|
.private = CGROUP_FILE_TASKS,
|
|
.write = cgroup1_tasks_write,
|
|
},
|
|
{
|
|
.name = "notify_on_release",
|
|
.read_u64 = cgroup_read_notify_on_release,
|
|
.write_u64 = cgroup_write_notify_on_release,
|
|
},
|
|
{
|
|
.name = "release_agent",
|
|
.flags = CFTYPE_ONLY_ON_ROOT,
|
|
.seq_show = cgroup_release_agent_show,
|
|
.write = cgroup_release_agent_write,
|
|
.max_write_len = PATH_MAX - 1,
|
|
},
|
|
{ } /* terminate */
|
|
};
|
|
|
|
/* Display information about each subsystem and each hierarchy */
|
|
int proc_cgroupstats_show(struct seq_file *m, void *v)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
|
|
/*
|
|
* ideally we don't want subsystems moving around while we do this.
|
|
* cgroup_mutex is also necessary to guarantee an atomic snapshot of
|
|
* subsys/hierarchy state.
|
|
*/
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
for_each_subsys(ss, i)
|
|
seq_printf(m, "%s\t%d\t%d\t%d\n",
|
|
ss->legacy_name, ss->root->hierarchy_id,
|
|
atomic_read(&ss->root->nr_cgrps),
|
|
cgroup_ssid_enabled(i));
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* cgroupstats_build - build and fill cgroupstats
|
|
* @stats: cgroupstats to fill information into
|
|
* @dentry: A dentry entry belonging to the cgroup for which stats have
|
|
* been requested.
|
|
*
|
|
* Build and fill cgroupstats so that taskstats can export it to user
|
|
* space.
|
|
*/
|
|
int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
|
|
{
|
|
struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
|
|
struct cgroup *cgrp;
|
|
struct css_task_iter it;
|
|
struct task_struct *tsk;
|
|
|
|
/* it should be kernfs_node belonging to cgroupfs and is a directory */
|
|
if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
|
|
kernfs_type(kn) != KERNFS_DIR)
|
|
return -EINVAL;
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
/*
|
|
* We aren't being called from kernfs and there's no guarantee on
|
|
* @kn->priv's validity. For this and css_tryget_online_from_dir(),
|
|
* @kn->priv is RCU safe. Let's do the RCU dancing.
|
|
*/
|
|
rcu_read_lock();
|
|
cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv);
|
|
if (!cgrp || cgroup_is_dead(cgrp)) {
|
|
rcu_read_unlock();
|
|
mutex_unlock(&cgroup_mutex);
|
|
return -ENOENT;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
css_task_iter_start(&cgrp->self, 0, &it);
|
|
while ((tsk = css_task_iter_next(&it))) {
|
|
switch (tsk->state) {
|
|
case TASK_RUNNING:
|
|
stats->nr_running++;
|
|
break;
|
|
case TASK_INTERRUPTIBLE:
|
|
stats->nr_sleeping++;
|
|
break;
|
|
case TASK_UNINTERRUPTIBLE:
|
|
stats->nr_uninterruptible++;
|
|
break;
|
|
case TASK_STOPPED:
|
|
stats->nr_stopped++;
|
|
break;
|
|
default:
|
|
if (delayacct_is_task_waiting_on_io(tsk))
|
|
stats->nr_io_wait++;
|
|
break;
|
|
}
|
|
}
|
|
css_task_iter_end(&it);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
return 0;
|
|
}
|
|
|
|
void cgroup1_check_for_release(struct cgroup *cgrp)
|
|
{
|
|
if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
|
|
!css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
|
|
schedule_work(&cgrp->release_agent_work);
|
|
}
|
|
|
|
/*
|
|
* Notify userspace when a cgroup is released, by running the
|
|
* configured release agent with the name of the cgroup (path
|
|
* relative to the root of cgroup file system) as the argument.
|
|
*
|
|
* Most likely, this user command will try to rmdir this cgroup.
|
|
*
|
|
* This races with the possibility that some other task will be
|
|
* attached to this cgroup before it is removed, or that some other
|
|
* user task will 'mkdir' a child cgroup of this cgroup. That's ok.
|
|
* The presumed 'rmdir' will fail quietly if this cgroup is no longer
|
|
* unused, and this cgroup will be reprieved from its death sentence,
|
|
* to continue to serve a useful existence. Next time it's released,
|
|
* we will get notified again, if it still has 'notify_on_release' set.
|
|
*
|
|
* The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
|
|
* means only wait until the task is successfully execve()'d. The
|
|
* separate release agent task is forked by call_usermodehelper(),
|
|
* then control in this thread returns here, without waiting for the
|
|
* release agent task. We don't bother to wait because the caller of
|
|
* this routine has no use for the exit status of the release agent
|
|
* task, so no sense holding our caller up for that.
|
|
*/
|
|
void cgroup1_release_agent(struct work_struct *work)
|
|
{
|
|
struct cgroup *cgrp =
|
|
container_of(work, struct cgroup, release_agent_work);
|
|
char *pathbuf, *agentbuf;
|
|
char *argv[3], *envp[3];
|
|
int ret;
|
|
|
|
/* snoop agent path and exit early if empty */
|
|
if (!cgrp->root->release_agent_path[0])
|
|
return;
|
|
|
|
/* prepare argument buffers */
|
|
pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
|
|
agentbuf = kmalloc(PATH_MAX, GFP_KERNEL);
|
|
if (!pathbuf || !agentbuf)
|
|
goto out_free;
|
|
|
|
spin_lock(&release_agent_path_lock);
|
|
strlcpy(agentbuf, cgrp->root->release_agent_path, PATH_MAX);
|
|
spin_unlock(&release_agent_path_lock);
|
|
if (!agentbuf[0])
|
|
goto out_free;
|
|
|
|
ret = cgroup_path_ns(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
|
|
if (ret < 0 || ret >= PATH_MAX)
|
|
goto out_free;
|
|
|
|
argv[0] = agentbuf;
|
|
argv[1] = pathbuf;
|
|
argv[2] = NULL;
|
|
|
|
/* minimal command environment */
|
|
envp[0] = "HOME=/";
|
|
envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
|
|
envp[2] = NULL;
|
|
|
|
call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
|
|
out_free:
|
|
kfree(agentbuf);
|
|
kfree(pathbuf);
|
|
}
|
|
|
|
/*
|
|
* cgroup_rename - Only allow simple rename of directories in place.
|
|
*/
|
|
static int cgroup1_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
|
|
const char *new_name_str)
|
|
{
|
|
struct cgroup *cgrp = kn->priv;
|
|
int ret;
|
|
|
|
if (kernfs_type(kn) != KERNFS_DIR)
|
|
return -ENOTDIR;
|
|
if (kn->parent != new_parent)
|
|
return -EIO;
|
|
|
|
/*
|
|
* We're gonna grab cgroup_mutex which nests outside kernfs
|
|
* active_ref. kernfs_rename() doesn't require active_ref
|
|
* protection. Break them before grabbing cgroup_mutex.
|
|
*/
|
|
kernfs_break_active_protection(new_parent);
|
|
kernfs_break_active_protection(kn);
|
|
|
|
mutex_lock(&cgroup_mutex);
|
|
|
|
ret = kernfs_rename(kn, new_parent, new_name_str);
|
|
if (!ret)
|
|
TRACE_CGROUP_PATH(rename, cgrp);
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
kernfs_unbreak_active_protection(kn);
|
|
kernfs_unbreak_active_protection(new_parent);
|
|
return ret;
|
|
}
|
|
|
|
static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_root)
|
|
{
|
|
struct cgroup_root *root = cgroup_root_from_kf(kf_root);
|
|
struct cgroup_subsys *ss;
|
|
int ssid;
|
|
|
|
for_each_subsys(ss, ssid)
|
|
if (root->subsys_mask & (1 << ssid))
|
|
seq_show_option(seq, ss->legacy_name, NULL);
|
|
if (root->flags & CGRP_ROOT_NOPREFIX)
|
|
seq_puts(seq, ",noprefix");
|
|
if (root->flags & CGRP_ROOT_XATTR)
|
|
seq_puts(seq, ",xattr");
|
|
if (root->flags & CGRP_ROOT_CPUSET_V2_MODE)
|
|
seq_puts(seq, ",cpuset_v2_mode");
|
|
|
|
spin_lock(&release_agent_path_lock);
|
|
if (strlen(root->release_agent_path))
|
|
seq_show_option(seq, "release_agent",
|
|
root->release_agent_path);
|
|
spin_unlock(&release_agent_path_lock);
|
|
|
|
if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
|
|
seq_puts(seq, ",clone_children");
|
|
if (strlen(root->name))
|
|
seq_show_option(seq, "name", root->name);
|
|
return 0;
|
|
}
|
|
|
|
enum cgroup1_param {
|
|
Opt_all,
|
|
Opt_clone_children,
|
|
Opt_cpuset_v2_mode,
|
|
Opt_name,
|
|
Opt_none,
|
|
Opt_noprefix,
|
|
Opt_release_agent,
|
|
Opt_xattr,
|
|
};
|
|
|
|
const struct fs_parameter_spec cgroup1_fs_parameters[] = {
|
|
fsparam_flag ("all", Opt_all),
|
|
fsparam_flag ("clone_children", Opt_clone_children),
|
|
fsparam_flag ("cpuset_v2_mode", Opt_cpuset_v2_mode),
|
|
fsparam_string("name", Opt_name),
|
|
fsparam_flag ("none", Opt_none),
|
|
fsparam_flag ("noprefix", Opt_noprefix),
|
|
fsparam_string("release_agent", Opt_release_agent),
|
|
fsparam_flag ("xattr", Opt_xattr),
|
|
{}
|
|
};
|
|
|
|
int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param)
|
|
{
|
|
struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
|
|
struct cgroup_subsys *ss;
|
|
struct fs_parse_result result;
|
|
int opt, i;
|
|
|
|
opt = fs_parse(fc, cgroup1_fs_parameters, param, &result);
|
|
if (opt == -ENOPARAM) {
|
|
if (strcmp(param->key, "source") == 0) {
|
|
fc->source = param->string;
|
|
param->string = NULL;
|
|
return 0;
|
|
}
|
|
for_each_subsys(ss, i) {
|
|
if (strcmp(param->key, ss->legacy_name))
|
|
continue;
|
|
ctx->subsys_mask |= (1 << i);
|
|
return 0;
|
|
}
|
|
return invalfc(fc, "Unknown subsys name '%s'", param->key);
|
|
}
|
|
if (opt < 0)
|
|
return opt;
|
|
|
|
switch (opt) {
|
|
case Opt_none:
|
|
/* Explicitly have no subsystems */
|
|
ctx->none = true;
|
|
break;
|
|
case Opt_all:
|
|
ctx->all_ss = true;
|
|
break;
|
|
case Opt_noprefix:
|
|
ctx->flags |= CGRP_ROOT_NOPREFIX;
|
|
break;
|
|
case Opt_clone_children:
|
|
ctx->cpuset_clone_children = true;
|
|
break;
|
|
case Opt_cpuset_v2_mode:
|
|
ctx->flags |= CGRP_ROOT_CPUSET_V2_MODE;
|
|
break;
|
|
case Opt_xattr:
|
|
ctx->flags |= CGRP_ROOT_XATTR;
|
|
break;
|
|
case Opt_release_agent:
|
|
/* Specifying two release agents is forbidden */
|
|
if (ctx->release_agent)
|
|
return invalfc(fc, "release_agent respecified");
|
|
ctx->release_agent = param->string;
|
|
param->string = NULL;
|
|
break;
|
|
case Opt_name:
|
|
/* blocked by boot param? */
|
|
if (cgroup_no_v1_named)
|
|
return -ENOENT;
|
|
/* Can't specify an empty name */
|
|
if (!param->size)
|
|
return invalfc(fc, "Empty name");
|
|
if (param->size > MAX_CGROUP_ROOT_NAMELEN - 1)
|
|
return invalfc(fc, "Name too long");
|
|
/* Must match [\w.-]+ */
|
|
for (i = 0; i < param->size; i++) {
|
|
char c = param->string[i];
|
|
if (isalnum(c))
|
|
continue;
|
|
if ((c == '.') || (c == '-') || (c == '_'))
|
|
continue;
|
|
return invalfc(fc, "Invalid name");
|
|
}
|
|
/* Specifying two names is forbidden */
|
|
if (ctx->name)
|
|
return invalfc(fc, "name respecified");
|
|
ctx->name = param->string;
|
|
param->string = NULL;
|
|
break;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int check_cgroupfs_options(struct fs_context *fc)
|
|
{
|
|
struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
|
|
u16 mask = U16_MAX;
|
|
u16 enabled = 0;
|
|
struct cgroup_subsys *ss;
|
|
int i;
|
|
|
|
#ifdef CONFIG_CPUSETS
|
|
mask = ~((u16)1 << cpuset_cgrp_id);
|
|
#endif
|
|
for_each_subsys(ss, i)
|
|
if (cgroup_ssid_enabled(i) && !cgroup1_ssid_disabled(i))
|
|
enabled |= 1 << i;
|
|
|
|
ctx->subsys_mask &= enabled;
|
|
|
|
/*
|
|
* In absense of 'none', 'name=' or subsystem name options,
|
|
* let's default to 'all'.
|
|
*/
|
|
if (!ctx->subsys_mask && !ctx->none && !ctx->name)
|
|
ctx->all_ss = true;
|
|
|
|
if (ctx->all_ss) {
|
|
/* Mutually exclusive option 'all' + subsystem name */
|
|
if (ctx->subsys_mask)
|
|
return invalfc(fc, "subsys name conflicts with all");
|
|
/* 'all' => select all the subsystems */
|
|
ctx->subsys_mask = enabled;
|
|
}
|
|
|
|
/*
|
|
* We either have to specify by name or by subsystems. (So all
|
|
* empty hierarchies must have a name).
|
|
*/
|
|
if (!ctx->subsys_mask && !ctx->name)
|
|
return invalfc(fc, "Need name or subsystem set");
|
|
|
|
/*
|
|
* Option noprefix was introduced just for backward compatibility
|
|
* with the old cpuset, so we allow noprefix only if mounting just
|
|
* the cpuset subsystem.
|
|
*/
|
|
if ((ctx->flags & CGRP_ROOT_NOPREFIX) && (ctx->subsys_mask & mask))
|
|
return invalfc(fc, "noprefix used incorrectly");
|
|
|
|
/* Can't specify "none" and some subsystems */
|
|
if (ctx->subsys_mask && ctx->none)
|
|
return invalfc(fc, "none used incorrectly");
|
|
|
|
return 0;
|
|
}
|
|
|
|
int cgroup1_reconfigure(struct fs_context *fc)
|
|
{
|
|
struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
|
|
struct kernfs_root *kf_root = kernfs_root_from_sb(fc->root->d_sb);
|
|
struct cgroup_root *root = cgroup_root_from_kf(kf_root);
|
|
int ret = 0;
|
|
u16 added_mask, removed_mask;
|
|
|
|
cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
|
|
|
|
/* See what subsystems are wanted */
|
|
ret = check_cgroupfs_options(fc);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
if (ctx->subsys_mask != root->subsys_mask || ctx->release_agent)
|
|
pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
|
|
task_tgid_nr(current), current->comm);
|
|
|
|
added_mask = ctx->subsys_mask & ~root->subsys_mask;
|
|
removed_mask = root->subsys_mask & ~ctx->subsys_mask;
|
|
|
|
/* Don't allow flags or name to change at remount */
|
|
if ((ctx->flags ^ root->flags) ||
|
|
(ctx->name && strcmp(ctx->name, root->name))) {
|
|
errorfc(fc, "option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"",
|
|
ctx->flags, ctx->name ?: "", root->flags, root->name);
|
|
ret = -EINVAL;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* remounting is not allowed for populated hierarchies */
|
|
if (!list_empty(&root->cgrp.self.children)) {
|
|
ret = -EBUSY;
|
|
goto out_unlock;
|
|
}
|
|
|
|
ret = rebind_subsystems(root, added_mask);
|
|
if (ret)
|
|
goto out_unlock;
|
|
|
|
WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask));
|
|
|
|
if (ctx->release_agent) {
|
|
spin_lock(&release_agent_path_lock);
|
|
strcpy(root->release_agent_path, ctx->release_agent);
|
|
spin_unlock(&release_agent_path_lock);
|
|
}
|
|
|
|
trace_cgroup_remount(root);
|
|
|
|
out_unlock:
|
|
mutex_unlock(&cgroup_mutex);
|
|
return ret;
|
|
}
|
|
|
|
struct kernfs_syscall_ops cgroup1_kf_syscall_ops = {
|
|
.rename = cgroup1_rename,
|
|
.show_options = cgroup1_show_options,
|
|
.mkdir = cgroup_mkdir,
|
|
.rmdir = cgroup_rmdir,
|
|
.show_path = cgroup_show_path,
|
|
};
|
|
|
|
/*
|
|
* The guts of cgroup1 mount - find or create cgroup_root to use.
|
|
* Called with cgroup_mutex held; returns 0 on success, -E... on
|
|
* error and positive - in case when the candidate is busy dying.
|
|
* On success it stashes a reference to cgroup_root into given
|
|
* cgroup_fs_context; that reference is *NOT* counting towards the
|
|
* cgroup_root refcount.
|
|
*/
|
|
static int cgroup1_root_to_use(struct fs_context *fc)
|
|
{
|
|
struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
|
|
struct cgroup_root *root;
|
|
struct cgroup_subsys *ss;
|
|
int i, ret;
|
|
|
|
/* First find the desired set of subsystems */
|
|
ret = check_cgroupfs_options(fc);
|
|
if (ret)
|
|
return ret;
|
|
|
|
/*
|
|
* Destruction of cgroup root is asynchronous, so subsystems may
|
|
* still be dying after the previous unmount. Let's drain the
|
|
* dying subsystems. We just need to ensure that the ones
|
|
* unmounted previously finish dying and don't care about new ones
|
|
* starting. Testing ref liveliness is good enough.
|
|
*/
|
|
for_each_subsys(ss, i) {
|
|
if (!(ctx->subsys_mask & (1 << i)) ||
|
|
ss->root == &cgrp_dfl_root)
|
|
continue;
|
|
|
|
if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt))
|
|
return 1; /* restart */
|
|
cgroup_put(&ss->root->cgrp);
|
|
}
|
|
|
|
for_each_root(root) {
|
|
bool name_match = false;
|
|
|
|
if (root == &cgrp_dfl_root)
|
|
continue;
|
|
|
|
/*
|
|
* If we asked for a name then it must match. Also, if
|
|
* name matches but sybsys_mask doesn't, we should fail.
|
|
* Remember whether name matched.
|
|
*/
|
|
if (ctx->name) {
|
|
if (strcmp(ctx->name, root->name))
|
|
continue;
|
|
name_match = true;
|
|
}
|
|
|
|
/*
|
|
* If we asked for subsystems (or explicitly for no
|
|
* subsystems) then they must match.
|
|
*/
|
|
if ((ctx->subsys_mask || ctx->none) &&
|
|
(ctx->subsys_mask != root->subsys_mask)) {
|
|
if (!name_match)
|
|
continue;
|
|
return -EBUSY;
|
|
}
|
|
|
|
if (root->flags ^ ctx->flags)
|
|
pr_warn("new mount options do not match the existing superblock, will be ignored\n");
|
|
|
|
ctx->root = root;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* No such thing, create a new one. name= matching without subsys
|
|
* specification is allowed for already existing hierarchies but we
|
|
* can't create new one without subsys specification.
|
|
*/
|
|
if (!ctx->subsys_mask && !ctx->none)
|
|
return invalfc(fc, "No subsys list or none specified");
|
|
|
|
/* Hierarchies may only be created in the initial cgroup namespace. */
|
|
if (ctx->ns != &init_cgroup_ns)
|
|
return -EPERM;
|
|
|
|
root = kzalloc(sizeof(*root), GFP_KERNEL);
|
|
if (!root)
|
|
return -ENOMEM;
|
|
|
|
ctx->root = root;
|
|
init_cgroup_root(ctx);
|
|
|
|
ret = cgroup_setup_root(root, ctx->subsys_mask);
|
|
if (ret)
|
|
cgroup_free_root(root);
|
|
return ret;
|
|
}
|
|
|
|
int cgroup1_get_tree(struct fs_context *fc)
|
|
{
|
|
struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
|
|
int ret;
|
|
|
|
/* Check if the caller has permission to mount. */
|
|
if (!ns_capable(ctx->ns->user_ns, CAP_SYS_ADMIN))
|
|
return -EPERM;
|
|
|
|
cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
|
|
|
|
ret = cgroup1_root_to_use(fc);
|
|
if (!ret && !percpu_ref_tryget_live(&ctx->root->cgrp.self.refcnt))
|
|
ret = 1; /* restart */
|
|
|
|
mutex_unlock(&cgroup_mutex);
|
|
|
|
if (!ret)
|
|
ret = cgroup_do_get_tree(fc);
|
|
|
|
if (!ret && percpu_ref_is_dying(&ctx->root->cgrp.self.refcnt)) {
|
|
struct super_block *sb = fc->root->d_sb;
|
|
dput(fc->root);
|
|
deactivate_locked_super(sb);
|
|
ret = 1;
|
|
}
|
|
|
|
if (unlikely(ret > 0)) {
|
|
msleep(10);
|
|
return restart_syscall();
|
|
}
|
|
return ret;
|
|
}
|
|
|
|
static int __init cgroup1_wq_init(void)
|
|
{
|
|
/*
|
|
* Used to destroy pidlists and separate to serve as flush domain.
|
|
* Cap @max_active to 1 too.
|
|
*/
|
|
cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
|
|
0, 1);
|
|
BUG_ON(!cgroup_pidlist_destroy_wq);
|
|
return 0;
|
|
}
|
|
core_initcall(cgroup1_wq_init);
|
|
|
|
static int __init cgroup_no_v1(char *str)
|
|
{
|
|
struct cgroup_subsys *ss;
|
|
char *token;
|
|
int i;
|
|
|
|
while ((token = strsep(&str, ",")) != NULL) {
|
|
if (!*token)
|
|
continue;
|
|
|
|
if (!strcmp(token, "all")) {
|
|
cgroup_no_v1_mask = U16_MAX;
|
|
continue;
|
|
}
|
|
|
|
if (!strcmp(token, "named")) {
|
|
cgroup_no_v1_named = true;
|
|
continue;
|
|
}
|
|
|
|
for_each_subsys(ss, i) {
|
|
if (strcmp(token, ss->name) &&
|
|
strcmp(token, ss->legacy_name))
|
|
continue;
|
|
|
|
cgroup_no_v1_mask |= 1 << i;
|
|
}
|
|
}
|
|
return 1;
|
|
}
|
|
__setup("cgroup_no_v1=", cgroup_no_v1);
|