From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755520AbaIWLq2 (ORCPT ); Tue, 23 Sep 2014 07:46:28 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36440 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753971AbaIWLqY (ORCPT ); Tue, 23 Sep 2014 07:46:24 -0400 Message-ID: <54215D52.8030201@redhat.com> Date: Tue, 23 Sep 2014 07:45:22 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.7.0 MIME-Version: 1.0 To: Steven Rostedt , Oleg Nesterov CC: Andrew Morton , "Paul E. McKenney" , Peter Zijlstra , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] signal: simplify deadlock-avoidance in lock_task_sighand() References: <20140922164404.GA28910@redhat.com> <20140922164437.GA28939@redhat.com> <20140922145828.4d06108a@gandalf.local.home> <20140922191130.GA4527@redhat.com> <20140922172405.71c4a110@gandalf.local.home> In-Reply-To: <20140922172405.71c4a110@gandalf.local.home> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 09/22/2014 05:24 PM, Steven Rostedt wrote: > On Mon, 22 Sep 2014 21:11:30 +0200 Oleg Nesterov > wrote: >> so this patch doesn't try to change the rules. >> >> But perhaps we can simply remove this preempt_disable/enable? >> >> Or. We can shift rcu_read_unlock() from lock_task_sighand() to >> unlock_task_sighand(). This way we can avoid preempt_disable too, >> but I'd prefer to not do this. > > I really thing the preempt_disable/enable is not needed. > > Paul, Thomas, care to comment? I suspect you are right. On normal kernels, rcu_read_lock() will ensure preemption is disabled. On -rt, the locks within are all sleepable mutexes. Either way, things should be ok. - -- All rights reversed -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAEBAgAGBQJUIV1SAAoJEM553pKExN6DXroIAIFFNLb1tDCHZCmW5q/so0U9 sd0MLhN/oRx9+tZuZw7RfIglTDEukMKuFI7lRvoIkH+uZ9ObRVqjGB35CWNVRaWy wzEyjIPO9OboHTCygBdxmLgC6I9Lg3qFQP2tuwLyEeWJMFylWuDDBtHCmVnbq78G AvUxyz9z+XuFSHLumD+DYMLkYSpMhzzCSSQ7uiOEYP+LA3a2DJuFgNxBvZWQAIu4 j7uWcWLlv3TJYkK7iTudJyXl4DqyhanILh5pHLXIv3w2I0tAycpPv73QH64Qog6S 3R5BoIrfFvfgldx1YaB26lk6jvg3jgi61fSaUx6ZoaMGBM+QBfxiNdI4G7Yn/8k= =EKgM -----END PGP SIGNATURE-----