Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751379AbWHXNW3 (ORCPT ); Thu, 24 Aug 2006 09:22:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751381AbWHXNW3 (ORCPT ); Thu, 24 Aug 2006 09:22:29 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:41903 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S1751379AbWHXNW2 (ORCPT ); Thu, 24 Aug 2006 09:22:28 -0400 Subject: Re: [PATCH] Fix x86_64 _spin_lock_irqsave() From: Arjan van de Ven To: Suleiman Souhlal Cc: Andi Kleen , Edward Falk , linux-kernel@vger.kernel.org In-Reply-To: <44ED9CB4.7070302@FreeBSD.org> References: <44ED157D.6050607@google.com> <44ED87AC.8070106@FreeBSD.org> <200608241332.40139.ak@suse.de> <44ED9CB4.7070302@FreeBSD.org> Content-Type: text/plain Organization: Intel International BV Date: Thu, 24 Aug 2006 15:21:58 +0200 Message-Id: <1156425718.3014.64.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1438 Lines: 40 On Thu, 2006-08-24 at 14:33 +0200, Suleiman Souhlal wrote: > Andi Kleen wrote: > > On Thursday 24 August 2006 13:04, Suleiman Souhlal wrote: > > > >>Andi Kleen wrote: > >> > >>>Edward Falk writes: > >>> > >>> > >>> > >>>>Add spin_lock_string_flags and _raw_spin_lock_flags() to > >>>>asm-x86_64/spinlock.h so that _spin_lock_irqsave() has the same > >>>>semantics on x86_64 as it does on i386 and does *not* have interrupts > >>>>disabled while it is waiting for the lock. > >>> > >>> > >>>Did it fix anything for you? > >> > >>I think this was to work around the fact that some buggy drivers try to > >>grab spinlocks without disabling interrupts when they should, which > >>would cause deadlocks when trying to rendez-vous every cpu via IPIs. > > > > > > That doesn't help them at all because they could then deadlock later. > > If the driver uses spin_lock() when it knows that the hardware won't > generate the interrupt that would need to be masked, and > spin_lock_irqsave() elsewhere, there shouldn't be any deadlocks unless > IPIs are involved. this still is bad practice and lockdep will also scream about it Can you point at ANY place that does this? - 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/