Commit 3b281afb authored by Tejun Heo's avatar Tejun Heo

cgroup: make css_next_child() skip missing csses

css_next_child() walks the children of the specified css.  It does
this by finding the next cgroup and then returning the requested css.
On the default unified hierarchy, a cgroup may not have a css
associated with it even if the hierarchy has the subsystem enabled.
This patch updates css_next_child() so that it skips children without
the requested css associated.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarLi Zefan <lizefan@huawei.com>
parent 2d8f243a
...@@ -2708,10 +2708,19 @@ css_next_child(struct cgroup_subsys_state *pos_css, ...@@ -2708,10 +2708,19 @@ css_next_child(struct cgroup_subsys_state *pos_css,
break; break;
} }
if (&next->sibling == &cgrp->children) /*
return NULL; * @next, if not pointing to the head, can be dereferenced and is
* the next sibling; however, it might have @ss disabled. If so,
* fast-forward to the next enabled one.
*/
while (&next->sibling != &cgrp->children) {
struct cgroup_subsys_state *next_css = cgroup_css(next, parent_css->ss);
return cgroup_css(next, parent_css->ss); if (next_css)
return next_css;
next = list_entry_rcu(next->sibling.next, struct cgroup, sibling);
}
return NULL;
} }
/** /**
......
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