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From: Darren Hart on 9 Jul 2010 18:40
If the pi_blocked_on variable is NULL, the subsequent WARN_ON's
will cause an OOPS. Only perform the susequent checks if
pi_blocked_on is valid.

Signed-off-by: Darren Hart <dvhltc(a)us.ibm.com>
Cc: Thomas Gleixner <tglx(a)linutronix.de>
Cc: Peter Zijlstra <peterz(a)infradead.org>
Cc: Ingo Molnar <mingo(a)elte.hu>
Cc: Eric Dumazet <eric.dumazet(a)gmail.com>
Cc: John Kacur <jkacur(a)redhat.com>
Cc: Steven Rostedt <rostedt(a)goodmis.org>
Cc: Mike Galbraith <efault(a)gmx.de>
---
kernel/rtmutex.c | 7 ++++---
1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/rtmutex.c b/kernel/rtmutex.c
index 23dd443..baac7d9 100644
--- a/kernel/rtmutex.c
+++ b/kernel/rtmutex.c
@@ -579,9 +579,10 @@ static void wakeup_next_waiter(struct rt_mutex *lock, int savestate)

raw_spin_lock(&pendowner->pi_lock);

- WARN_ON(!pendowner->pi_blocked_on);
- WARN_ON(pendowner->pi_blocked_on != waiter);
- WARN_ON(pendowner->pi_blocked_on->lock != lock);
+ if (!WARN_ON(!pendowner->pi_blocked_on)) {
+ WARN_ON(pendowner->pi_blocked_on != waiter);
+ WARN_ON(pendowner->pi_blocked_on->lock != lock);
+ }

pendowner->pi_blocked_on = NULL;

--
1.7.0.4

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