diff options
Diffstat (limited to 'include/linux/spinlock.h')
| -rw-r--r-- | include/linux/spinlock.h | 35 |
1 files changed, 25 insertions, 10 deletions
diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index 80e535897de..3f2867ff0ce 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -55,8 +55,8 @@ #include <linux/kernel.h> #include <linux/stringify.h> #include <linux/bottom_half.h> +#include <asm/barrier.h> -#include <asm/system.h> /* * Must define these before including other files, inline functions need them @@ -81,7 +81,7 @@ #include <linux/spinlock_types.h> /* - * Pull the arch_spin*() functions/declarations (UP-nondebug doesnt need them): + * Pull the arch_spin*() functions/declarations (UP-nondebug doesn't need them): */ #ifdef CONFIG_SMP # include <asm/spinlock.h> @@ -117,9 +117,27 @@ 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 + +/* + * Place this after a lock-acquisition primitive to guarantee that + * an UNLOCK+LOCK pair act as a full barrier. This guarantee applies + * if the UNLOCK and LOCK are executed by the same CPU or if the + * UNLOCK and LOCK operate on the same lock variable. + */ +#ifndef smp_mb__after_unlock_lock +#define smp_mb__after_unlock_lock() do { } while (0) #endif /** @@ -375,16 +393,13 @@ static inline int spin_can_lock(spinlock_t *lock) return raw_spin_can_lock(&lock->rlock); } -static inline void assert_spin_locked(spinlock_t *lock) -{ - assert_raw_spin_locked(&lock->rlock); -} +#define assert_spin_locked(lock) assert_raw_spin_locked(&(lock)->rlock) /* * Pull the atomic_t declaration: * (asm-mips/atomic.h needs above definitions) */ -#include <asm/atomic.h> +#include <linux/atomic.h> /** * atomic_dec_and_lock - lock on reaching reference count zero * @atomic: the atomic counter |