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| author | David S. Miller <davem@davemloft.net> | 2013-08-16 15:37:26 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-08-16 15:37:26 -0700 |
| commit | 2ff1cf12c9fe70e75e600404e6a4274b19d293ed (patch) | |
| tree | beafddac0a8098e3f07d2ec60e44a2a7d006e605 /include/linux/spinlock.h | |
| parent | 16b304f3404f8e0243d5ee2b70b68767b7b59b2b (diff) | |
| parent | 0f7dd1aa8f959216f1faa71513b9d3c1a9065e5a (diff) | |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
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 7d537ced949a..75f34949d9ab 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 /** |