The rwsem_can_spin_on_owner() function can be called with preemption enabled. This patch moves it before preempt_disable() so that it won't do unnecessary preemption operations when spinning is not possible.
Signed-off-by: Waiman Long <[email protected]> --- kernel/locking/rwsem-xadd.c | 6 +++--- 1 files changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c index ddd56d2..c8887ba 100644 --- a/kernel/locking/rwsem-xadd.c +++ b/kernel/locking/rwsem-xadd.c @@ -404,11 +404,11 @@ static bool rwsem_optimistic_spin(struct rw_semaphore *sem) bool taken = false; int spincnt = 0; - preempt_disable(); - /* sem->wait_lock should not be held when doing optimistic spinning */ if (!rwsem_can_spin_on_owner(sem)) - goto done; + return false; + + preempt_disable(); if (!osq_lock(&sem->osq)) goto done; -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
