Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261233AbVCWJvF (ORCPT ); Wed, 23 Mar 2005 04:51:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261278AbVCWJvE (ORCPT ); Wed, 23 Mar 2005 04:51:04 -0500 Received: from arnor.apana.org.au ([203.14.152.115]:45833 "EHLO arnor.apana.org.au") by vger.kernel.org with ESMTP id S261233AbVCWJu5 (ORCPT ); Wed, 23 Mar 2005 04:50:57 -0500 Date: Wed, 23 Mar 2005 20:49:54 +1100 To: Ingo Molnar Cc: paulmck@us.ibm.com, linux-kernel@vger.kernel.org, simlo@phys.au.dk Subject: Re: [patch] Real-Time Preemption, -RT-2.6.12-rc1-V0.7.41-07 Message-ID: <20050323094954.GA14052@gondor.apana.org.au> References: <20050323063317.GB31626@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.6+20040907i From: Herbert Xu Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 999 Lines: 24 On Wed, Mar 23, 2005 at 08:38:11PM +1100, Herbert Xu wrote: > > > ok. It's enough to put a barrier into the else branch here, because the > > atomic op in the main brain is a barrier by itself. > > Since the else branch is only taken when rcu_read_lock_nesting > 0, do > we need the barrier at all? Actually, since atomic_inc isn't a barrier, we do need that mb. However, it should only be necessary in the main branch and we can use smp_mb__after_atomic_inc which is optimised away on a number of architectures (i386 in particular). Cheers, -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt - 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/