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 <[email protected]> Acked-by: Michal Koutný <[email protected]> Signed-off-by: Tejun Heo <[email protected]>
ambv · Feb 12, 2020 · 3010c5b · 3010c5b
1 parent 0418938
commit 3010c5b
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
@@ -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;
 	}