From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751613AbeEDRvY (ORCPT ); Fri, 4 May 2018 13:51:24 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:45332 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751307AbeEDRvX (ORCPT ); Fri, 4 May 2018 13:51:23 -0400 Date: Fri, 4 May 2018 10:52:41 -0700 From: "Paul E. McKenney" To: "Eric W. Biederman" Cc: Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, tglx@linutronix.de, Anna-Maria Gleixner Subject: Re: [PATCH] kernel/signal: Remove no longer required irqsave/restore Reply-To: paulmck@linux.vnet.ibm.com References: <20180504144014.5378-1-bigeasy@linutronix.de> <87fu37e4rn.fsf@xmission.com> <20180504170459.624e7vkro5fn2bgw@linutronix.de> <876043e3xb.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <876043e3xb.fsf@xmission.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18050417-0044-0000-0000-0000040FBC50 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008970; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000258; SDB=6.01027471; UDB=6.00524848; IPR=6.00806605; MB=3.00020930; MTD=3.00000008; XFM=3.00000015; UTC=2018-05-04 17:51:20 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18050417-0045-0000-0000-00000841C609 Message-Id: <20180504175241.GT26088@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-05-04_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1805040163 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 04, 2018 at 12:17:20PM -0500, Eric W. Biederman wrote: > Sebastian Andrzej Siewior writes: > > > On 2018-05-04 11:59:08 [-0500], Eric W. Biederman wrote: > >> Sebastian Andrzej Siewior writes: > >> > From: Anna-Maria Gleixner > > … > >> > This long-term fix has been made in commit 4abf91047cf ("rtmutex: Make > > >> > wait_lock irq safe") for different reason. > >> > >> Which tree has this change been made in? I am not finding the commit > >> you mention above in Linus's tree. > > > > I'm sorry, it should have been commit b4abf91047cf ("rtmutex: Make > > wait_lock irq safe"). > > Can you fix that in your patch description and can you also up the > description of rcu_read_unlock? > > If we don't need to jump through hoops it looks very reasonable to > remove this unnecessary logic. But we should fix the description > in rcu_read_unlock that still says we need these hoops. The hoops are still required for rcu_read_lock(), otherwise you get deadlocks between the scheduler and RCU in PREEMPT=y kernels. What happens with this patch (if I understand it correctly) is that the signal code now uses a different way of jumping through the hoops. But the hoops are still jumped through. Thanx, Paul