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| author | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2013-11-14 17:38:05 -0800 |
|---|---|---|
| committer | Dmitry Torokhov <dmitry.torokhov@gmail.com> | 2013-11-14 17:38:05 -0800 |
| commit | 42249094f79422fbf5ed4b54eeb48ff096809b8f (patch) | |
| tree | 91e6850c8c7e8cc284cf8bb6363f8662f84011f4 /include/linux/spinlock.h | |
| parent | 936816161978ca716a56c5e553c68f25972b1e3a (diff) | |
| parent | 2c027b7c48a888ab173ba45babb4525e278375d9 (diff) | |
| download | lwn-42249094f79422fbf5ed4b54eeb48ff096809b8f.tar.gz lwn-42249094f79422fbf5ed4b54eeb48ff096809b8f.zip | |
Merge branch 'next' into for-linus
Merge first round of changes for 3.13 merge window.
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 /** |