From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCHv5 2/2] memory barrier: adding smp_mb__after_lock
Date: Fri, 3 Jul 2009 11:06:06 +0200
Message-ID: <20090703090606.GA3902@elte.hu>
References: <20090703081219.GE2902@jolsa.lab.eng.brq.redhat.com> <20090703081445.GG2902@jolsa.lab.eng.brq.redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	fbl@redhat.com, nhorman@redhat.com, davem@redhat.com,
	htejun@gmail.com, jarkao2@gmail.com, oleg@redhat.com,
	davidel@xmailserver.org, eric.dumazet@gmail.com
To: Jiri Olsa <jolsa@redhat.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Return-path: <netdev-owner@vger.kernel.org>
Received: from mx3.mail.elte.hu ([157.181.1.138]:59293 "EHLO mx3.mail.elte.hu"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1750896AbZGCJGW (ORCPT <rfc822;netdev@vger.kernel.org>);
	Fri, 3 Jul 2009 05:06:22 -0400
Content-Disposition: inline
In-Reply-To: <20090703081445.GG2902@jolsa.lab.eng.brq.redhat.com>
Sender: netdev-owner@vger.kernel.org
List-ID: <netdev.vger.kernel.org>


* Jiri Olsa <jolsa@redhat.com> 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