From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754927AbYIIPHa (ORCPT ); Tue, 9 Sep 2008 11:07:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751442AbYIIPHW (ORCPT ); Tue, 9 Sep 2008 11:07:22 -0400 Received: from e36.co.us.ibm.com ([32.97.110.154]:55586 "EHLO e36.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751176AbYIIPHU (ORCPT ); Tue, 9 Sep 2008 11:07:20 -0400 Date: Tue, 9 Sep 2008 07:54:53 -0700 From: "Paul E. McKenney" To: David Miller Cc: linux-kernel@vger.kernel.org, wli@holomorphy.com, sparclinux@vger.kernel.org, manfred@colorfullife.com, akpm@linux-foundation.org Subject: Re: [PATCH] prevent sparc64 from invoking irq handlers on offline CPUs Message-ID: <20080909145453.GA6711@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20080903004211.GD6748@linux.vnet.ibm.com> <20080903.022138.31681256.davem@davemloft.net> <20080903154217.GA6807@linux.vnet.ibm.com> <20080908.171708.43575256.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080908.171708.43575256.davem@davemloft.net> User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 08, 2008 at 05:17:08PM -0700, David Miller wrote: > From: "Paul E. McKenney" > Date: Wed, 3 Sep 2008 08:42:17 -0700 > > o Timer irqs. Not sure what happens to add_timer() calls from > > a CPU that is going offline. The hope would be that they get > > queued to some other CPU? > > This case is interesting, and I'm no sure what happens here. It turns out that there is a timer_cpu_modifier() that invokes migrate_timers() upon CPU_DEAD or CPU_DEAD_FROZEN. And migrate_timers() looks like it does what its name says. And I believe that CPU_DEAD happens after sparc64's local_irq_enable() window, so we should be OK. Thanx, Paul