From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754731Ab2HNIcP (ORCPT ); Tue, 14 Aug 2012 04:32:15 -0400 Received: from www.linutronix.de ([62.245.132.108]:56909 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754482Ab2HNIcK (ORCPT ); Tue, 14 Aug 2012 04:32:10 -0400 Date: Tue, 14 Aug 2012 10:32:06 +0200 (CEST) From: Thomas Gleixner To: Tejun Heo cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, mingo@redhat.com, akpm@linux-foundation.org, peterz@infradead.org Subject: Re: [PATCHSET] timer: clean up initializers and implement irqsafe timers In-Reply-To: <20120813233520.GG25632@google.com> Message-ID: References: <1344449428-24962-1-git-send-email-tj@kernel.org> <20120813233520.GG25632@google.com> User-Agent: Alpine 2.02 (LFD 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 13 Aug 2012, Tejun Heo wrote: > Hello, > > On Wed, Aug 08, 2012 at 11:10:24AM -0700, Tejun Heo wrote: > > Timer internals are protected by irqsafe lock but the lock is > > naturally dropped and irq enabled while a timer is executed. This > > makes dequeueing timer for execution and the actual execution > > non-atomic against IRQs. No matter what the timer function does, IRQs > > can occur between timer dispatch and execution. This means that an > > IRQ handler could interrupt any timer in progress and it's impossible > > for an IRQ handler to cancel and drain a timer. > > If nobody objects, I'll route this through wq/for-3.7 together with > "workqueue: use irqsafe timer in delayed_work" patchset. If you > object, please scream. SCREAM! I'll reply to the original posting later - still processing my vacation backlog. Thanks, tglx