From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shan Hai Subject: Re: [PATCH V2 1/1] lib/atomic64 using raw_spin_lock_irq[save|resotre] for atomicity Date: Fri, 02 Sep 2011 08:48:33 +0800 Message-ID: <4E6027E1.1090905@gmail.com> References: <1314847923-26428-1-git-send-email-haishan.bai@gmail.com> <1314847923-26428-2-git-send-email-haishan.bai@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: akpm@linux-foundation.org, eric.dumazet@gmail.com, vapier@gentoo.org, asharma@fb.com, linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org To: Thomas Gleixner Return-path: Received: from mail-wy0-f174.google.com ([74.125.82.174]:50736 "EHLO mail-wy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932747Ab1IBAsZ (ORCPT ); Thu, 1 Sep 2011 20:48:25 -0400 In-Reply-To: Sender: linux-rt-users-owner@vger.kernel.org List-ID: On 09/01/2011 06:11 PM, Thomas Gleixner wrote: > On Thu, 1 Sep 2011, Thomas Gleixner wrote: > >> On Thu, 1 Sep 2011, Shan Hai wrote: >> >>> The spin_lock_irq[save|restore] could break the atomicity of the >>> atomic64_* operations in the PREEMPT-RT configuration, because >>> the spin_lock_irq[save|restore] themselves are preemptable in the >>> PREEMPT-RT, using raw variant of the spin lock could provide the >>> atomicity that atomic64_* need. >> Good catch. Queued for the next release. > Though the changelog is misleading. The reason is not that they are > preemtible. > > The reason for your OOPs is that the sleeping locks are not IRQ > safe. And your system simply deadlocked due to that. > Will correct it in the V3 patch, thanks for the advice. Cheers Shan Hai > Thanks, > > tglx > -- > 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/