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: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 5f9ba58..c288bce 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -800,9 +800,8 @@
* 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);
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index dd55244..2b7354f 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3112,7 +3112,7 @@
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 @@
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 @@
do {
last = pos;
- pos = list_first_or_null_rcu(&pos->children, struct cgroup,
- sibling);
+ pos = cgroup_next_child(NULL, pos);
} while (pos);
return last;