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| author | Sage Weil <sage@inktank.com> | 2013-08-15 11:11:45 -0700 |
|---|---|---|
| committer | Sage Weil <sage@inktank.com> | 2013-08-15 11:11:45 -0700 |
| commit | ee3e542fec6e69bc9fb668698889a37d93950ddf (patch) | |
| tree | e74ee766a4764769ef1d3d45d266b4dea64101d3 /include/linux/spinlock.h | |
| parent | fe2a801b50c0bb8039d627e5ae1fec249d10ff39 (diff) | |
| parent | f1d6e17f540af37bb1891480143669ba7636c4cf (diff) | |
Merge remote-tracking branch 'linus/master' into testing
Diffstat (limited to 'include/linux/spinlock.h')
| -rw-r--r-- | include/linux/spinlock.h | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index 7d537ced949..75f34949d9a 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -117,9 +117,17 @@ do { \ #endif /*arch_spin_is_contended*/ #endif -/* The lock does not imply full memory barrier. */ -#ifndef ARCH_HAS_SMP_MB_AFTER_LOCK -static inline void smp_mb__after_lock(void) { smp_mb(); } +/* + * Despite its name it doesn't necessarily has to be a full barrier. + * It should only guarantee that a STORE before the critical section + * can not be reordered with a LOAD inside this section. + * spin_lock() is the one-way barrier, this LOAD can not escape out + * of the region. So the default implementation simply ensures that + * a STORE can not move into the critical section, smp_wmb() should + * serialize it with another STORE done by spin_lock(). + */ +#ifndef smp_mb__before_spinlock +#define smp_mb__before_spinlock() smp_wmb() #endif /** |