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Commit f48e3924 authored by Tejun Heo's avatar Tejun Heo
Browse files

cgroup: always use cgroup_next_child() to walk the children list 



There are several places where the children list is accessed directly.
This patch converts those places to use cgroup_next_child().  This
will help updating the hierarchy iterators to use @css instead of
@cgrp.

While cgroup_next_child() can be heavy in pathological cases - e.g. a
lot of dead children, this shouldn't cause any noticeable behavior
differences.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent 3b287a50

include/linux/cgroup.h

+2 −3
Original line number Diff line number Diff line
@@ -800,9 +800,8 @@ struct cgroup *cgroup_next_child(struct cgroup *pos, struct cgroup *cgrp); 
 * the start of the next iteration by, for example, bumping the css refcnt.

 */

#define cgroup_for_each_child(pos, cgrp)				\

	for ((pos) = list_first_or_null_rcu(&(cgrp)->children,		\

					    struct cgroup, sibling);	\

	     (pos); (pos) = cgroup_next_child((pos), (cgrp)))

	for ((pos) = cgroup_next_child(NULL, (cgrp)); (pos);		\

	     (pos) = cgroup_next_child((pos), (cgrp)))



struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,

					  struct cgroup *cgroup);

kernel/cgroup.c

+3 −4
Original line number Diff line number Diff line
@@ -3112,7 +3112,7 @@ struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos, 
		pos = cgroup;



	/* visit the first child if exists */

	next = list_first_or_null_rcu(&pos->children, struct cgroup, sibling);

	next = cgroup_next_child(NULL, pos);

	if (next)

		return next;
@@ -3151,7 +3151,7 @@ struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos) 
		last = pos;

		/* ->prev isn't RCU safe, walk ->next till the end */

		pos = NULL;

		list_for_each_entry_rcu(tmp, &last->children, sibling)

		cgroup_for_each_child(tmp, last)

			pos = tmp;

	} while (pos);
@@ -3165,8 +3165,7 @@ static struct cgroup *cgroup_leftmost_descendant(struct cgroup *pos) 


	do {

		last = pos;

		pos = list_first_or_null_rcu(&pos->children, struct cgroup,

					     sibling);

		pos = cgroup_next_child(NULL, pos);

	} while (pos);



	return last;