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

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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: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
This commit is contained in:
Tejun Heo 2013-08-08 20:11:24 -04:00
parent 3b287a505e
commit f48e3924dc
2 changed files with 5 additions and 7 deletions
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5
include/linux/cgroup.h
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@ -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);

7
kernel/cgroup.c
View File

@ -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;