From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754598AbcGESAE (ORCPT ); Tue, 5 Jul 2016 14:00:04 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:35026 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751105AbcGESAA (ORCPT ); Tue, 5 Jul 2016 14:00:00 -0400 X-IBM-Helo: d01dlp02.pok.ibm.com X-IBM-MailFrom: paulmck@linux.vnet.ibm.com Date: Tue, 5 Jul 2016 10:59:59 -0700 From: "Paul E. McKenney" To: Peter Zijlstra Cc: Stephen Rothwell , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Daniel Vetter , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, Chris Wilson Subject: Re: linux-next: build failure after merge of the tip tree (from the drm-intel tree) Reply-To: paulmck@linux.vnet.ibm.com References: <20160705135303.6a1bc80a@canb.auug.org.au> <20160705082512.GX30921@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160705082512.GX30921@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16070517-0040-0000-0000-000000BBADA6 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16070517-0041-0000-0000-00000495CE58 Message-Id: <20160705175959.GW4650@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-07-05_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1607050160 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 05, 2016 at 10:25:12AM +0200, Peter Zijlstra wrote: > On Tue, Jul 05, 2016 at 01:53:03PM +1000, Stephen Rothwell wrote: > > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > > index d3502c0603e5..1f91f187b2a8 100644 > > --- a/drivers/gpu/drm/i915/i915_gem.c > > +++ b/drivers/gpu/drm/i915/i915_gem.c > > @@ -3290,7 +3290,7 @@ i915_gem_retire_work_handler(struct work_struct *work) > > * We do not need to do this test under locking as in the worst-case > > * we queue the retire worker once too often. > > */ > > - if (lockless_dereference(dev_priv->gt.awake)) > > + if (/*lockless_dereference*/(dev_priv->gt.awake)) > > queue_delayed_work(dev_priv->wq, > > &dev_priv->gt.retire_work, > > round_jiffies_up_relative(HZ)); > > diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c > > index f6de8dd567a2..2c1926418691 100644 > > --- a/drivers/gpu/drm/i915/i915_irq.c > > +++ b/drivers/gpu/drm/i915/i915_irq.c > > @@ -3095,7 +3095,7 @@ static void i915_hangcheck_elapsed(struct work_struct *work) > > if (!i915.enable_hangcheck) > > return; > > > > - if (!lockless_dereference(dev_priv->gt.awake)) > > + if (!/*lockless_dereference*/(dev_priv->gt.awake)) > > return; > > > > /* As enabling the GPU requires fairly extensive mmio access, > > Right, neither case appears to include a data dependency and thus > lockless_dereference() seems misguided. Agreed! At first glance, this code wants READ_ONCE() rather than lockless_dereference(). Thanx, Paul