Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754077Ab1EEMkC (ORCPT ); Thu, 5 May 2011 08:40:02 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:58777 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753901Ab1EEMkA (ORCPT ); Thu, 5 May 2011 08:40:00 -0400 Date: Thu, 5 May 2011 08:39:59 -0400 From: Christoph Hellwig To: Dave Chinner Cc: linux-kernel@vger.kernel.org, Markus Trippelsdorf , Bruno Pr?mont , xfs-masters@oss.sgi.com, xfs@oss.sgi.com, Christoph Hellwig , Alex Elder , Dave Chinner Subject: Re: 2.6.39-rc3, 2.6.39-rc4: XFS lockup - regression since 2.6.38 Message-ID: <20110505123959.GA21098@infradead.org> References: <20110423224403.5fd1136a@neptune.home> <20110427050850.GG12436@dastard> <20110427182622.05a068a2@neptune.home> <20110428194528.GA1627@x4.trippels.de> <20110429011929.GA13542@dastard> <20110504005736.GA2958@cucamonga.audible.transient.net> <20110505002126.GA26797@dastard> <20110505022613.GA26837@dastard> <20110505122117.GB26837@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110505122117.GB26837@dastard> User-Agent: Mutt/1.5.21 (2010-09-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1421 Lines: 35 > The third problem is that updating the push target is not safe on 32 > bit machines. We cannot copy a 64 bit LSN without the possibility of > corrupting the result when racing with another updating thread. We > have function to do this update safely without needing to care about > 32/64 bit issues - xfs_trans_ail_copy_lsn() - so use that when > updating the AIL push target. But reading xa_target without xa_lock isn't safe on 32-bit either, is it? For the first read it can trivially be moved into the critical section a few lines below, and the second one should probably use XFS_LSN_CMP. > @@ -482,19 +481,24 @@ xfs_ail_worker( > /* assume we have more work to do in a short while */ > tout = 10; > if (!count) { > +out_done: Jumping into conditionals is really ugly. By initializing count a bit earlier you can just jump in front of the if/else clauses. And while you're there maybe moving the tout = 10; into an else clause would also make the code more readable. an uninitialied used of tout. > + if (ailp->xa_target == target || > + (test_and_set_bit(XFS_AIL_PUSHING_BIT, &ailp->xa_flags))) no need for braces around the test_and_set_bit call. -- 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/