memory barrier: adding smp_mb__after_lock (ad462769) · Commits · 戴 / test

arch/x86/include/asm/spinlock.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -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 */

+5 −0

Original line number	Diff line number	Diff line
		@@ -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.

+4 −1

Original line number	Diff line number	Diff line
		@@ -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);
		}