Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759711AbYG3Jop (ORCPT ); Wed, 30 Jul 2008 05:44:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760340AbYG3JoN (ORCPT ); Wed, 30 Jul 2008 05:44:13 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:35962 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759951AbYG3JoK (ORCPT ); Wed, 30 Jul 2008 05:44:10 -0400 Date: Wed, 30 Jul 2008 02:43:29 -0700 From: Andrew Morton To: Simon Horman Cc: Keith Owens , linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, Tony Luck Subject: Re: [patch] IA64: only call up() in salinfo_work_to_do() if down_trylock() was successful Message-Id: <20080730024329.404eccc3.akpm@linux-foundation.org> In-Reply-To: <20080729130742.GA20158@verge.net.au> References: <20080729094718.GA5247@verge.net.au> <1163.1217335629@ocs10w> <20080729130742.GA20158@verge.net.au> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1873 Lines: 46 On Tue, 29 Jul 2008 23:07:45 +1000 Simon Horman wrote: > On Tue, Jul 29, 2008 at 10:47:09PM +1000, Keith Owens wrote: > > Simon Horman (on Tue, 29 Jul 2008 19:47:20 +1000) wrote: > > >Aesthetic issues aside is it safe to call up() if down_trylock() failed? > > > > > >arch/ia64/kernel/salinfo.c: In function `salinfo_work_to_do': > > >arch/ia64/kernel/salinfo.c:195: warning: ignoring return value of `down_trylock' > > > > > >Signed-off-by: Simon Horman > > > > > >Index: linux-2.6/arch/ia64/kernel/salinfo.c > > >=================================================================== > > >--- linux-2.6.orig/arch/ia64/kernel/salinfo.c 2008-07-29 19:06:33.000000000 +1000 > > >+++ linux-2.6/arch/ia64/kernel/salinfo.c 2008-07-29 19:40:02.000000000 +1000 > > >@@ -192,8 +192,8 @@ struct salinfo_platform_oemdata_parms { > > > static void > > > salinfo_work_to_do(struct salinfo_data *data) > > > { > > >- down_trylock(&data->mutex); > > >- up(&data->mutex); > > >+ if (down_trylock(&data->mutex) == 0) > > >+ up(&data->mutex); > > > } > > > > > > static void > > > > NAK. The whole point of this function is to set the mutex to the up > > state, irrespective of whether it was already down or not. Tracking > > the state of data->mutex in all the possible contexts is just too > > fragile, especially since it can be modified from NMI context. > > salinfo_work_to_do() ensures that the mtuex ends in the up state. boggle. I daren't look. > > To remove the warning, just stick '(void)' in front of down_trylock(). > > Thanks, will do. > For gawd's sake add a comment there too. -- 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/