From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754886Ab2HMXf2 (ORCPT ); Mon, 13 Aug 2012 19:35:28 -0400 Received: from mail-yx0-f174.google.com ([209.85.213.174]:53217 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754155Ab2HMXf0 (ORCPT ); Mon, 13 Aug 2012 19:35:26 -0400 Date: Mon, 13 Aug 2012 16:35:20 -0700 From: Tejun Heo To: linux-kernel@vger.kernel.org Cc: torvalds@linux-foundation.org, mingo@redhat.com, akpm@linux-foundation.org, tglx@linutronix.de, peterz@infradead.org Subject: Re: [PATCHSET] timer: clean up initializers and implement irqsafe timers Message-ID: <20120813233520.GG25632@google.com> References: <1344449428-24962-1-git-send-email-tj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1344449428-24962-1-git-send-email-tj@kernel.org> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Thanks. -- tejun