Commit 3010c5b9 authored Jan 18, 2020 by Madhuparna Bhowmik Committed by Tejun Heo Feb 12, 2020

cgroup.c: Use built-in RCU list checking



list_for_each_entry_rcu has built-in RCU and lock checking.
Pass cond argument to list_for_each_entry_rcu() to silence
false lockdep warning when  CONFIG_PROVE_RCU_LIST is enabled
by default.

Even though the function css_next_child() already checks if
cgroup_mutex or rcu_read_lock() is held using
cgroup_assert_mutex_or_rcu_locked(), there is a need to pass
cond to list_for_each_entry_rcu() to avoid false positive
lockdep warning.

Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
Acked-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

parent 04189382

kernel/cgroup/cgroup.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -4148,7 +4148,8 @@ struct cgroup_subsys_state css_next_child(struct cgroup_subsys_state pos,
		} else if (likely(!(pos->flags & CSS_RELEASED))) {
		next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling);
		} else {
		list_for_each_entry_rcu(next, &parent->children, sibling)
		list_for_each_entry_rcu(next, &parent->children, sibling,
		lockdep_is_held(&cgroup_mutex))
		if (next->serial_nr > pos->serial_nr)
		break;
		}

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