>From memory ordering point of view, spin_unlock_wait() provides the same guarantees as spin_lock(); spin_unlock().
Therefore the smp_mb() after spin_lock() is not necessary, spin_unlock_wait() must provide the memory ordering. Signed-off-by: Manfred Spraul <[email protected]> Cc: Will Deacon <[email protected]> --- ipc/sem.c | 8 -------- 1 file changed, 8 deletions(-) diff --git a/ipc/sem.c b/ipc/sem.c index 6586e0a..a5da82c 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -355,14 +355,6 @@ static inline int sem_lock(struct sem_array *sma, struct sembuf *sops, */ spin_lock(&sem->lock); - /* - * See 51d7d5205d33 - * ("powerpc: Add smp_mb() to arch_spin_is_locked()"): - * A full barrier is required: the write of sem->lock - * must be visible before the read is executed - */ - smp_mb(); - if (!smp_load_acquire(&sma->complex_mode)) { /* fast path successful! */ return sops->sem_num; -- 2.7.4
