cgroup: make css_next_child() skip missing csses (3b281afb) · Commits · 戴 / test

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:

Tejun Heo <tj@kernel.org> Acked-by:

Li Zefan <lizefan@huawei.com>

kernel/cgroup.c

+12 −3

Original line number	Diff line number	Diff line
		@@ -2708,10 +2708,19 @@ css_next_child(struct cgroup_subsys_state *pos_css,
		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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