Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760909AbZLKHyt (ORCPT ); Fri, 11 Dec 2009 02:54:49 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934847AbZLKHyl (ORCPT ); Fri, 11 Dec 2009 02:54:41 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:50757 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760691AbZLKHyg (ORCPT ); Fri, 11 Dec 2009 02:54:36 -0500 Date: Fri, 11 Dec 2009 08:54:08 +0100 From: Ingo Molnar To: Dave Chinner Cc: "Rafael J. Wysocki" , Alan Stern , Linus Torvalds , Zhang Rui , LKML , ACPI Devel Maling List , pm list , Peter Zijlstra , Lachlan McIlroy Subject: Re: spinlock in completion_done() (was: Re: Async resume patch (was: Re: [GIT PULL] PM updates for 2.6.33)) Message-ID: <20091211075408.GB31149@elte.hu> References: <200912082248.14138.rjw@sisk.pl> <20091209092922.GC28428@elte.hu> <200912092337.52492.rjw@sisk.pl> <20091210075947.GD25549@elte.hu> <20091211041041.GJ30608@discord.disaster> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091211041041.GJ30608@discord.disaster> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: 0.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=0.0 required=5.9 tests=none autolearn=no SpamAssassin version=3.2.5 _SUMMARY_ Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1592 Lines: 34 * Dave Chinner wrote: > On Thu, Dec 10, 2009 at 08:59:47AM +0100, Ingo Molnar wrote: > > * Rafael J. Wysocki wrote: > > > On Wednesday 09 December 2009, Ingo Molnar wrote: > > > > * Rafael J. Wysocki wrote: > > > > > On Tuesday 08 December 2009, Alan Stern wrote: > > > > > > On Tue, 8 Dec 2009, Rafael J. Wysocki wrote: > > > > > > > > > > > > > BTW, is there a good reason why completion_done() doesn't use spin_lock_irqsave > > > > > > > and spin_unlock_irqrestore? complete() and complete_all() use them, so why not > > > > > > > here? > > > > > > > > > > > > And likewise in try_wait_for_completion(). It looks like a bug. Maybe > > > > > > these routines were not intended to be called with interrupts disabled, > > > > > > but that requirement doesn't seem to be documented. And it isn't a > > > > > > natural requirement anyway. > > When I implemented them they were not called from anywhere that > disabled interrupts. IIRC the main reason I used spin_lock_irq() > was because that is what wait_for_completion() used at the time.... Obviously wait_for_competion() as a non-atomic API that can block will (and should) use _irq() - but atomic variants (complete, but also the try-wait thing) use irqsafe methods. A fair portion of completions happen in IRQ context. Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/