[PATCH] lock/lockdep: Add missing graph_unlock in validate_chain

[Xuewen Yan]

The lookup_chain_cache_add will get graph_lock, but the
validate_chain do not unlock before return 0.

So add graph_unlock before return 0.

Signed-off-by: Xuewen Yan <xuewen.yan@xxxxxxxxxx>
Signed-off-by: Zhiguo Niu <zhiguo.niu@xxxxxxxxxx>
---
 kernel/locking/lockdep.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 151bd3de5936..24995e1ebc62 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3855,8 +3855,11 @@ static int validate_chain(struct task_struct *curr,
 		 */
 		int ret = check_deadlock(curr, hlock);
 
-		if (!ret)
+		if (!ret) {
+			graph_unlock();
 			return 0;
+		}
+
 		/*
 		 * Add dependency only if this lock is not the head
 		 * of the chain, and if the new lock introduces no more
@@ -3865,9 +3868,9 @@ static int validate_chain(struct task_struct *curr,
 		 * serializes nesting locks), see the comments for
 		 * check_deadlock().
 		 */
-		if (!chain_head && ret != 2) {
-			if (!check_prevs_add(curr, hlock))
-				return 0;
+		if (!chain_head && ret != 2 && !check_prevs_add(curr, hlock)) {
+			graph_unlock();
+			return 0;
 		}
 
 		graph_unlock();
-- 
2.25.1