locking/rtmutex: Use READ_ONCE() in rt_mutex_owner()
authorThomas Gleixner <tglx@linutronix.de>
Wed, 30 Nov 2016 21:04:42 +0000 (21:04 +0000)
committerIngo Molnar <mingo@kernel.org>
Fri, 2 Dec 2016 10:13:26 +0000 (11:13 +0100)
commit1be5d4fa0af34fb7bafa205aeb59f5c7cc7a089d
treefc9508b47018bfd363d78fff07b2591d96d3c300
parentdbb26055defd03d59f678cb5f2c992abe05b064a
locking/rtmutex: Use READ_ONCE() in rt_mutex_owner()

While debugging the rtmutex unlock vs. dequeue race Will suggested to use
READ_ONCE() in rt_mutex_owner() as it might race against the
cmpxchg_release() in unlock_rt_mutex_safe().

Will: "It's a minor thing which will most likely not matter in practice"

Careful search did not unearth an actual problem in todays code, but it's
better to be safe than surprised.

Suggested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: David Daney <ddaney@caviumnetworks.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20161130210030.431379999@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
kernel/locking/rtmutex_common.h