[PATCH] rt_mutex: don't initialize lockdep when not required

["Levin, Alexander (Sasha Levin)" <alexander.levin@verizon.com>]

pi_mutex isn't supposed to be tracked by lockdep, but just
passing NULLs for name and key will cause lockdep to spew a
warning and die, which is not what we want it to do.

Skip lockdep initialization if the caller passed NULLs for
name and key, suggesting such initialization isn't desired.

Fixes: f5694788ad8d ("rt_mutex: Add lockdep annotations")
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
---
 kernel/locking/rtmutex.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 43123533e9b1..78069895032a 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1661,7 +1661,8 @@ void __rt_mutex_init(struct rt_mutex *lock, const char *name,
 	lock->waiters = RB_ROOT;
 	lock->waiters_leftmost = NULL;
 
-	debug_rt_mutex_init(lock, name, key);
+	if (name && key)
+		debug_rt_mutex_init(lock, name, key);
 }
 EXPORT_SYMBOL_GPL(__rt_mutex_init);
 
-- 
2.11.0