diff options
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 { \ | |||
117 | #endif /*arch_spin_is_contended*/ | 117 | #endif /*arch_spin_is_contended*/ |
118 | #endif | 118 | #endif |
119 | 119 | ||
120 | /* The lock does not imply full memory barrier. */ | 120 | /* |
121 | #ifndef ARCH_HAS_SMP_MB_AFTER_LOCK | 121 | * Despite its name it doesn't necessarily has to be a full barrier. |
122 | static inline void smp_mb__after_lock(void) { smp_mb(); } | 122 | * It should only guarantee that a STORE before the critical section |
123 | * can not be reordered with a LOAD inside this section. | ||
124 | * spin_lock() is the one-way barrier, this LOAD can not escape out | ||
125 | * of the region. So the default implementation simply ensures that | ||
126 | * a STORE can not move into the critical section, smp_wmb() should | ||
127 | * serialize it with another STORE done by spin_lock(). | ||
128 | */ | ||
129 | #ifndef smp_mb__before_spinlock | ||
130 | #define smp_mb__before_spinlock() smp_wmb() | ||
123 | #endif | 131 | #endif |
124 | 132 | ||
125 | /** | 133 | /** |