Subject: Re: [PATCHv5 2/2] memory barrier: adding smp_mb__after_lock

From: Ingo Molnar <[email-masked]>
Date: Fri, 3 Jul 2009 11:06:06 +0200

* Jiri Olsa <[email-masked]> wrote:

> +++ b/arch/x86/include/asm/spinlock.h
> @@ -302,4 +302,7 @@ 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. */
> +#define smp_mb__after_lock() do { } while (0)

Two small stylistic comments, please make this an inline function:

static inline void smp_mb__after_lock(void) { }
#define smp_mb__after_lock

(untested)

> +/* The lock does not imply full memory barrier. */
> +#ifndef smp_mb__after_lock
> +#define smp_mb__after_lock() smp_mb()
> +#endif

ditto.

	Ingo