From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753218Ab0CWM07 (ORCPT ); Tue, 23 Mar 2010 08:26:59 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:32921 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753080Ab0CWM04 convert rfc822-to-8bit (ORCPT ); Tue, 23 Mar 2010 08:26:56 -0400 Subject: Re: [PATCH] smp_call_function_many SMP race From: Peter Zijlstra To: Anton Blanchard Cc: Xiao Guangrong , Ingo Molnar , Jens Axboe , Nick Piggin , Rusty Russell , Andrew Morton , Linus Torvalds , paulmck@linux.vnet.ibm.com, Milton Miller , Nick Piggin , linux-kernel@vger.kernel.org In-Reply-To: <20100323111556.GK24064@kryten> References: <20100323111556.GK24064@kryten> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Tue, 23 Mar 2010 13:26:43 +0100 Message-ID: <1269347203.5279.1650.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2010-03-23 at 22:15 +1100, Anton Blanchard wrote: > > It turns out commit c0f68c2fab4898bcc4671a8fb941f428856b4ad5 (generic-ipi: > cleanup for generic_smp_call_function_interrupt()) is at fault. It removes > locking from smp_call_function_many and in doing so creates a rather > complicated race. A rather simple question since my brain isn't quite ready processing the content here.. Isn't reverting that one patch a simpler solution than adding all that extra logic? If not, then the above statement seems false and we had a bug even with that preempt_enable/disable() pair. Just wondering.. :-)