Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756908AbZGCJVK (ORCPT ); Fri, 3 Jul 2009 05:21:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754616AbZGCJUz (ORCPT ); Fri, 3 Jul 2009 05:20:55 -0400 Received: from gw1.cosmosbay.com ([212.99.114.194]:38692 "EHLO gw1.cosmosbay.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753211AbZGCJUz (ORCPT ); Fri, 3 Jul 2009 05:20:55 -0400 Message-ID: <4A4DCD54.1080908@gmail.com> Date: Fri, 03 Jul 2009 11:20:20 +0200 From: Eric Dumazet User-Agent: Thunderbird 2.0.0.22 (Windows/20090605) MIME-Version: 1.0 To: Ingo Molnar CC: Jiri Olsa , Peter Zijlstra , Mathieu Desnoyers , 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 Subject: Re: [PATCHv5 2/2] memory barrier: adding smp_mb__after_lock References: <20090703081219.GE2902@jolsa.lab.eng.brq.redhat.com> <20090703081445.GG2902@jolsa.lab.eng.brq.redhat.com> <20090703090606.GA3902@elte.hu> In-Reply-To: <20090703090606.GA3902@elte.hu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-1.6 (gw1.cosmosbay.com [0.0.0.0]); Fri, 03 Jul 2009 11:20:21 +0200 (CEST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1320 Lines: 45 Ingo Molnar a ?crit : > * Jiri Olsa 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 This was following existing implementations of various smp_mb__??? helpers : # grep -4 smp_mb__before_clear_bit include/asm-generic/bitops.h /* * clear_bit may not imply a memory barrier */ #ifndef smp_mb__before_clear_bit #define smp_mb__before_clear_bit() smp_mb() #define smp_mb__after_clear_bit() smp_mb() #endif -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/