From: Hernan Ponce de Leon <hernanl.leon@xxxxxxxxxx> Following the defition of data race in tools/memory-model/linux-kernel.cat the dartagnan tool https://github.com/hernanponcedeleon/Dat3M reported a race between mark_rt_mutex_waiters and rt_mutex_cmpxchg_release. Commit 23f78d4a03c5 ("[PATCH] pi-futex: rt mutex core") later removed in commit d0aa7a70bf03 ("futex_requeue_pi optimization") and reverted in commit bd197234b0a6 ("Revert "futex_requeue_pi optimization"") The original commit introduced the data race. Cc: stable@xxxxxxxxxxxxxxx # v2.6.18.x Fixes: 23f78d4a03c5 ("[PATCH] pi-futex: rt mutex core") Signed-off-by: Hernan Ponce de Leon <hernanl.leon@xxxxxxxxxx> --- kernel/locking/rtmutex.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 010cf4e6d0b8..7ed9472edd48 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -235,7 +235,7 @@ static __always_inline void mark_rt_mutex_waiters(struct rt_mutex_base *lock) unsigned long owner, *p = (unsigned long *) &lock->owner; do { - owner = *p; + owner = READ_ONCE(*p); } while (cmpxchg_relaxed(p, owner, owner | RT_MUTEX_HAS_WAITERS) != owner); -- 2.25.1
