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Commit 389b9c1b authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: keep css_set and task lists in chronological order 



css task iteration will be updated to not leak cgroup internal locking
to iterator users.  In preparation, update css_set and task lists to
be in chronological order.

For tasks, as migration path is already using list_splice_tail_init(),
only cgroup_enable_task_cg_lists() and cgroup_post_fork() need
updating.  For css_sets, link_css_set() is the only place which needs
to be updated.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 91486f61

kernel/cgroup.c

+5 −6
Original line number Diff line number Diff line
@@ -914,12 +914,11 @@ static void link_css_set(struct list_head *tmp_links, struct css_set *cset, 
	link->cset = cset;

	link->cgrp = cgrp;



	list_move(&link->cset_link, &cgrp->cset_links);



	/*

	 * Always add links to the tail of the list so that the list

	 * is sorted by order of hierarchy creation

	 * Always add links to the tail of the lists so that the lists are

	 * in choronological order.

	 */

	list_move_tail(&link->cset_link, &cgrp->cset_links);

	list_add_tail(&link->cgrp_link, &cset->cgrp_links);



	if (cgroup_parent(cgrp))
@@ -1780,7 +1779,7 @@ static void cgroup_enable_task_cg_lists(void) 


			if (!css_set_populated(cset))

				css_set_update_populated(cset, true);

			list_add(&p->cg_list, &cset->tasks);

			list_add_tail(&p->cg_list, &cset->tasks);

			get_css_set(cset);

		}

		spin_unlock_irq(&p->sighand->siglock);
@@ -5480,7 +5479,7 @@ void cgroup_post_fork(struct task_struct *child, 
		cset = task_css_set(current);

		if (list_empty(&child->cg_list)) {

			rcu_assign_pointer(child->cgroups, cset);

			list_add(&child->cg_list, &cset->tasks);

			list_add_tail(&child->cg_list, &cset->tasks);

			get_css_set(cset);

		}

		up_write(&css_set_rwsem);