From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: spinlock in completion_done() (was: Re: Async resume patch (was: Re: [GIT PULL] PM updates for 2.6.33)) Date: Wed, 9 Dec 2009 10:29:22 +0100 Message-ID: <20091209092922.GC28428@elte.hu> References: <200912082248.14138.rjw@sisk.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx3.mail.elte.hu ([157.181.1.138]:52019 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752611AbZLIJaT (ORCPT ); Wed, 9 Dec 2009 04:30:19 -0500 Content-Disposition: inline In-Reply-To: <200912082248.14138.rjw@sisk.pl> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "Rafael J. Wysocki" Cc: Alan Stern , Linus Torvalds , Zhang Rui , LKML , ACPI Devel Maling List , pm list , Peter Zijlstra , David Chinner , Lachlan McIlroy * 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. > > OK, let's ask Ingo about that. > > Ingo, is there any particular reason why completion_done() and > try_wait_for_completion() don't use spin_lock_irqsave() and > spin_unlock_irqrestore()? that's a bug that should be fixed - all the wakeup side (and atomic) variants of completetion API should be irq safe. It appears that these new completion APIs were added via the XFS tree about a year ago: 39d2f1a: [XFS] extend completions to provide XFS object flush requirements Please Cc: scheduler folks to all scheduler patches. Ingo