1 /* SPDX-License-Identifier: GPL-2.0 */
8  *  Copyright (C) 2004-2006 Silicon Graphics, Inc.
28 #include <linux/cgroup-defs.h>
66 	struct list_head		iters_node;	/* css_set->task_iters */
85  * cgroup_subsys_enabled - fast test on whether a subsys is enabled
86  * @ss: subsystem in question
92  * cgroup_subsys_on_dfl - fast test on whether a subsys is on default hierarchy
93  * @ss: subsystem in question
163  * css_for_each_child - iterate through children of a css
169  * If a subsystem synchronizes ->css_online() and the start of iteration, a
170  * css which finished ->css_online() is guaranteed to be visible in the
172  * A css which hasn't finished ->css_online() or already finished
173  * ->css_offline() may show up during traversal.  It's each subsystem's
185  * css_for_each_descendant_pre - pre-order walk of a css's descendants
192  * If a subsystem synchronizes ->css_online() and the start of iteration, a
193  * css which finished ->css_online() is guaranteed to be visible in the
195  * A css which hasn't finished ->css_online() or already finished
196  * ->css_offline() may show up during traversal.  It's each subsystem's
222  * enclosed inside @pos locking, double-locking the parent isn't necessary
230  * iteration should lock and unlock both @pos->parent and @pos.
232  * Alternatively, a subsystem may choose to use a single global lock to
233  * synchronize ->css_online() and ->css_offline() against tree-walking
245  * css_for_each_descendant_post - post-order walk of a css's descendants
249  * Similar to css_for_each_descendant_pre() but performs post-order
253  * If a subsystem synchronizes ->css_online() and the start of iteration, a
254  * css which finished ->css_online() is guaranteed to be visible in the
256  * A css which hasn't finished ->css_online() or already finished
257  * ->css_offline() may show up during traversal.  It's each subsystem's
260  * Note that the walk visibility guarantee example described in pre-order
261  * walk doesn't apply the same to post-order walks.
268  * cgroup_taskset_for_each - iterate cgroup_taskset
291  * cgroup_taskset_for_each_leader - iterate group leaders in a cgroup_taskset
296  * Iterate threadgroup leaders of @tset.  For single-task migrations, @tset
303 		if ((leader) != (leader)->group_leader)			\
326 	return cgrp->kn->id;  in cgroup_id()
330  * css_is_dying - test whether the specified css is dying
334  * most cases, ->css_online() and ->css_offline() callbacks should be
346 	return !(css->flags & CSS_NO_REF) && percpu_ref_is_dying(&css->refcnt);  in css_is_dying()
351 	css_get(&cgrp->self);  in cgroup_get()
356 	return css_tryget(&cgrp->self);  in cgroup_tryget()
361 	css_put(&cgrp->self);  in cgroup_put()
377  * task_css_set_check - obtain a task's css_set with extra access conditions
391 	rcu_dereference_check((task)->cgroups,				\
395 		((task)->flags & PF_EXITING) || (__c))
398 	rcu_dereference((task)->cgroups)
402  * task_css_check - obtain css for (task, subsys) w/ extra access conds
404  * @subsys_id: the target subsystem ID
411 	task_css_set_check((task), (__c))->subsys[(subsys_id)]
414  * task_css_set - obtain a task's css_set
425  * task_css - obtain css for (task, subsys)
427  * @subsys_id: the target subsystem ID
438  * task_get_css - find and get the css for (task, subsys)
440  * @subsys_id: the target subsystem ID
469  * task_css_is_root - test whether a task belongs to the root css
471  * @subsys_id: the target subsystem ID
473  * Test whether @task belongs to the root css on the specified subsystem.
485 	return task_css(task, subsys_id)->cgroup;  in task_cgroup()
490 	return task_css_set(task)->dfl_cgrp;  in task_dfl_cgroup()
495 	struct cgroup_subsys_state *parent_css = cgrp->self.parent;  in cgroup_parent()
503  * cgroup_is_descendant - test ancestry
514 	if (cgrp->root != ancestor->root || cgrp->level < ancestor->level)  in cgroup_is_descendant()
516 	return cgrp->ancestors[ancestor->level] == ancestor;  in cgroup_is_descendant()
520  * cgroup_ancestor - find ancestor of cgroup
522  * @ancestor_level: level of ancestor to find starting from root
524  * Find ancestor of cgroup at specified level starting from root if it exists
533 	if (ancestor_level < 0 || ancestor_level > cgrp->level)  in cgroup_ancestor()
535 	return cgrp->ancestors[ancestor_level];  in cgroup_ancestor()
539  * task_under_cgroup_hierarchy - test task's membership of cgroup ancestry
552 	return cgroup_is_descendant(cset->dfl_cgrp, ancestor);  in task_under_cgroup_hierarchy()
558 	return cgrp->nr_populated_csets + cgrp->nr_populated_domain_children +  in cgroup_is_populated()
559 		cgrp->nr_populated_threaded_children;  in cgroup_is_populated()
565 	return kernfs_ino(cgrp->kn);  in cgroup_ino()
568 /* cft/css accessors for cftype->write() operation */
571 	return of->kn->priv;  in of_cft()
576 /* cft/css accessors for cftype->seq_*() operations */
579 	return of_cft(seq->private);  in seq_cft()
584 	return of_css(seq->private);  in seq_css()
594 	return kernfs_name(cgrp->kn, buf, buflen);  in cgroup_name()
599 	return kernfs_path(cgrp->kn, buf, buflen);  in cgroup_path()
604 	pr_cont_kernfs_name(cgrp->kn);  in pr_cont_cgroup_name()
609 	pr_cont_kernfs_path(cgrp->kn);  in pr_cont_cgroup_path()
621 	current->no_cgroup_migration = 1;  in cgroup_init_kthreadd()
630 	current->no_cgroup_migration = 0;  in cgroup_kthread_ready()
648 				    struct dentry *dentry) { return -EINVAL; }  in cgroupstats_build()
747  * sock->sk_cgrp_data handling.  For more info, see sock_cgroup_data
748  * definition in cgroup-defs.h.
758 	return skcd->cgroup;  in sock_cgroup_ptr()
804 		refcount_inc(&ns->ns.count);  in get_cgroup_ns()
809 	if (ns && refcount_dec_and_test(&ns->ns.count))  in put_cgroup_ns()
824 	return task->frozen;  in cgroup_task_frozen()
841 	percpu_ref_get(&cgrp->bpf.refcnt);  in cgroup_bpf_get()
846 	percpu_ref_put(&cgrp->bpf.refcnt);  in cgroup_bpf_put()