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
164  * css_for_each_child - iterate through children of a css
170  * If a subsystem synchronizes ->css_online() and the start of iteration, a
171  * css which finished ->css_online() is guaranteed to be visible in the
173  * A css which hasn't finished ->css_online() or already finished
174  * ->css_offline() may show up during traversal.  It's each subsystem's
186  * css_for_each_descendant_pre - pre-order walk of a css's descendants
193  * If a subsystem synchronizes ->css_online() and the start of iteration, a
194  * css which finished ->css_online() is guaranteed to be visible in the
196  * A css which hasn't finished ->css_online() or already finished
197  * ->css_offline() may show up during traversal.  It's each subsystem's
223  * enclosed inside @pos locking, double-locking the parent isn't necessary
231  * iteration should lock and unlock both @pos->parent and @pos.
233  * Alternatively, a subsystem may choose to use a single global lock to
234  * synchronize ->css_online() and ->css_offline() against tree-walking
246  * css_for_each_descendant_post - post-order walk of a css's descendants
250  * Similar to css_for_each_descendant_pre() but performs post-order
254  * If a subsystem synchronizes ->css_online() and the start of iteration, a
255  * css which finished ->css_online() is guaranteed to be visible in the
257  * A css which hasn't finished ->css_online() or already finished
258  * ->css_offline() may show up during traversal.  It's each subsystem's
261  * Note that the walk visibility guarantee example described in pre-order
262  * walk doesn't apply the same to post-order walks.
269  * cgroup_taskset_for_each - iterate cgroup_taskset
292  * cgroup_taskset_for_each_leader - iterate group leaders in a cgroup_taskset
297  * Iterate threadgroup leaders of @tset.  For single-task migrations, @tset
304 		if ((leader) != (leader)->group_leader)			\
327 	return cgrp->kn->id;  in cgroup_id()
331  * css_is_dying - test whether the specified css is dying
335  * most cases, ->css_online() and ->css_offline() callbacks should be
347 	return css->flags & CSS_DYING;  in css_is_dying()
352 	css_get(&cgrp->self);  in cgroup_get()
357 	return css_tryget(&cgrp->self);  in cgroup_tryget()
362 	css_put(&cgrp->self);  in cgroup_put()
378  * task_css_set_check - obtain a task's css_set with extra access conditions
392 	rcu_dereference_check((task)->cgroups,				\
396 		((task)->flags & PF_EXITING) || (__c))
399 	rcu_dereference((task)->cgroups)
403  * task_css_check - obtain css for (task, subsys) w/ extra access conds
405  * @subsys_id: the target subsystem ID
412 	task_css_set_check((task), (__c))->subsys[(subsys_id)]
415  * task_css_set - obtain a task's css_set
426  * task_css - obtain css for (task, subsys)
428  * @subsys_id: the target subsystem ID
439  * task_get_css - find and get the css for (task, subsys)
441  * @subsys_id: the target subsystem ID
470  * task_css_is_root - test whether a task belongs to the root css
472  * @subsys_id: the target subsystem ID
474  * Test whether @task belongs to the root css on the specified subsystem.
486 	return task_css(task, subsys_id)->cgroup;  in task_cgroup()
491 	return task_css_set(task)->dfl_cgrp;  in task_dfl_cgroup()
496 	struct cgroup_subsys_state *parent_css = cgrp->self.parent;  in cgroup_parent()
504  * cgroup_is_descendant - test ancestry
515 	if (cgrp->root != ancestor->root || cgrp->level < ancestor->level)  in cgroup_is_descendant()
517 	return cgrp->ancestors[ancestor->level] == ancestor;  in cgroup_is_descendant()
521  * cgroup_ancestor - find ancestor of cgroup
523  * @ancestor_level: level of ancestor to find starting from root
525  * Find ancestor of cgroup at specified level starting from root if it exists
534 	if (ancestor_level < 0 || ancestor_level > cgrp->level)  in cgroup_ancestor()
536 	return cgrp->ancestors[ancestor_level];  in cgroup_ancestor()
540  * task_under_cgroup_hierarchy - test task's membership of cgroup ancestry
553 	return cgroup_is_descendant(cset->dfl_cgrp, ancestor);  in task_under_cgroup_hierarchy()
559 	return cgrp->nr_populated_csets + cgrp->nr_populated_domain_children +  in cgroup_is_populated()
560 		cgrp->nr_populated_threaded_children;  in cgroup_is_populated()
566 	return kernfs_ino(cgrp->kn);  in cgroup_ino()
569 /* cft/css accessors for cftype->write() operation */
572 	return of->kn->priv;  in of_cft()
577 /* cft/css accessors for cftype->seq_*() operations */
580 	return of_cft(seq->private);  in seq_cft()
585 	return of_css(seq->private);  in seq_css()
595 	return kernfs_name(cgrp->kn, buf, buflen);  in cgroup_name()
600 	return kernfs_path(cgrp->kn, buf, buflen);  in cgroup_path()
605 	pr_cont_kernfs_name(cgrp->kn);  in pr_cont_cgroup_name()
610 	pr_cont_kernfs_path(cgrp->kn);  in pr_cont_cgroup_path()
622 	current->no_cgroup_migration = 1;  in cgroup_init_kthreadd()
631 	current->no_cgroup_migration = 0;  in cgroup_kthread_ready()
649 				    struct dentry *dentry) { return -EINVAL; }  in cgroupstats_build()
746  * sock->sk_cgrp_data handling.  For more info, see sock_cgroup_data
747  * definition in cgroup-defs.h.
757 	return skcd->cgroup;  in sock_cgroup_ptr()
803 		refcount_inc(&ns->ns.count);  in get_cgroup_ns()
808 	if (ns && refcount_dec_and_test(&ns->ns.count))  in put_cgroup_ns()
823 	return task->frozen;  in cgroup_task_frozen()
840 	percpu_ref_get(&cgrp->bpf.refcnt);  in cgroup_bpf_get()
845 	percpu_ref_put(&cgrp->bpf.refcnt);  in cgroup_bpf_put()