Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753590AbcCILlB (ORCPT ); Wed, 9 Mar 2016 06:41:01 -0500 Received: from port70.net ([81.7.13.123]:45138 "EHLO port70.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753448AbcCILkx (ORCPT ); Wed, 9 Mar 2016 06:40:53 -0500 Date: Wed, 9 Mar 2016 12:40:51 +0100 From: Szabolcs Nagy To: Ingo Molnar , Andy Lutomirski , x86@kernel.org, linux-kernel@vger.kernel.org, Borislav Petkov , "musl@lists.openwall.com" , Linus Torvalds , Andrew Morton , Thomas Gleixner , Peter Zijlstra Subject: Re: [musl] Re: [RFC PATCH] x86/vdso/32: Add AT_SYSINFO cancellation helpers Message-ID: <20160309114051.GA29662@port70.net> Mail-Followup-To: Ingo Molnar , Andy Lutomirski , x86@kernel.org, linux-kernel@vger.kernel.org, Borislav Petkov , "musl@lists.openwall.com" , Linus Torvalds , Andrew Morton , Thomas Gleixner , Peter Zijlstra References: <06079088639eddd756e2092b735ce4a682081308.1457486598.git.luto@kernel.org> <20160309085631.GA3247@gmail.com> <20160309113449.GZ29662@port70.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160309113449.GZ29662@port70.net> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 568 Lines: 13 * Szabolcs Nagy [2016-03-09 12:34:50 +0100]: > * Ingo Molnar [2016-03-09 09:56:31 +0100]: > > Why is so much complexity added to avoid a ~3 instructions window where > > calcellation is tested? Cancellation at work atom boundaries is a fundamentally > > 'polling' model anyway, and signal delivery is asynchronous, with a fundamental > > IPI delay if it's cross-CPU. > > > > to avoid the race when the thread is cancelled after the test but before > the syscall see http://ewontfix.com/16/ > wrong link http://ewontfix.com/2/