From: Madhuparna Bhowmik <madhuparnabhowmik10@xxxxxxxxx>
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@xxxxxxxxx>
---
kernel/cgroup/cgroup.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 735af8f15f95..c2959764ad95 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -4152,7 +4152,8 @@ 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;
}
--
2.17.1
