Fix deadlock patch

Author: knizhnik

src/backend/storage/lmgr/proc.c

@@ -1669,15 +1669,15 @@ CheckDeadLock(void)
 	int			i;
 
 
-	if (!pg_atomic_test_set_flag(&ProcGlobal->activeDeadlockCheck))
-		return;
-
 	/*
 	 * Ensure that only one backend is checking for deadlock.
 	 * Otherwise under high load cascade of deadlock timeout expirations can cause stuck of Postgres.
 	 */
 	if (!pg_atomic_test_set_flag(&ProcGlobal->activeDeadlockCheck))
+	{
+		enable_timeout_after(DEADLOCK_TIMEOUT, DeadlockTimeout);
 		return;
+	}
 	inside_deadlock_check = true;
 
 	/*