diff options
| -rw-r--r-- | arch/x86/include/asm/spinlock.h | 4 | ||||
| -rw-r--r-- | include/linux/spinlock.h | 5 | ||||
| -rw-r--r-- | include/net/sock.h | 5 |
3 files changed, 13 insertions, 1 deletions
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h index b7e5db87639..4e77853321d 100644 --- a/arch/x86/include/asm/spinlock.h +++ b/arch/x86/include/asm/spinlock.h @@ -302,4 +302,8 @@ static inline void __raw_write_unlock(raw_rwlock_t *rw) #define _raw_read_relax(lock) cpu_relax() #define _raw_write_relax(lock) cpu_relax() +/* The {read|write|spin}_lock() on x86 are full memory barriers. */ +static inline void smp_mb__after_lock(void) { } +#define ARCH_HAS_SMP_MB_AFTER_LOCK + #endif /* _ASM_X86_SPINLOCK_H */ diff --git a/include/linux/spinlock.h b/include/linux/spinlock.h index 252b245cfcf..4be57ab0347 100644 --- a/include/linux/spinlock.h +++ b/include/linux/spinlock.h @@ -132,6 +132,11 @@ do { \ #endif /*__raw_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(); } +#endif + /** * spin_unlock_wait - wait until the spinlock gets unlocked * @lock: the spinlock in question. diff --git a/include/net/sock.h b/include/net/sock.h index 4eb8409249f..2c0da9239b9 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1271,6 +1271,9 @@ static inline int sk_has_allocations(const struct sock *sk) * in its cache, and so does the tp->rcv_nxt update on CPU2 side. The CPU1 * could then endup calling schedule and sleep forever if there are no more * data on the socket. + * + * The sk_has_sleeper is always called right after a call to read_lock, so we + * can use smp_mb__after_lock barrier. */ static inline int sk_has_sleeper(struct sock *sk) { @@ -1280,7 +1283,7 @@ static inline int sk_has_sleeper(struct sock *sk) * * This memory barrier is paired in the sock_poll_wait. */ - smp_mb(); + smp_mb__after_lock(); return sk->sk_sleep && waitqueue_active(sk->sk_sleep); } |