From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tim Gardner Subject: Re: [PATCH V3] block: Mitigate lock unbalance caused by lock switching Date: Tue, 29 May 2012 07:45:22 -0600 Message-ID: <4FC4D2F2.2070309@gmail.com> References: <20120528102214.GB15202@dhcp-172-17-108-109.mtv.corp.google.com> <1338255542-22247-1-git-send-email-asias@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Jens Axboe , Tejun Heo , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, tim.gardner@canonical.com To: Asias He Return-path: Received: from mail.tpi.com ([70.99.223.143]:3856 "EHLO mail.tpi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752129Ab2E2Nqc (ORCPT ); Tue, 29 May 2012 09:46:32 -0400 In-Reply-To: <1338255542-22247-1-git-send-email-asias@redhat.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On 05/28/2012 07:39 PM, Asias He wrote: > @@ -440,6 +435,11 @@ void blk_cleanup_queue(struct request_queue *q) > del_timer_sync(&q->backing_dev_info.laptop_mode_wb_timer); > blk_sync_queue(q); > > + spin_lock_irq(lock); > + if (q->queue_lock != &q->__queue_lock) > + q->queue_lock = &q->__queue_lock; > + spin_unlock_irq(lock); > + Isn't the 'if' clause superfluous ? You could just do the assignment, e.g., + spin_lock_irq(lock); + q->queue_lock = &q->__queue_lock; + spin_unlock_irq(lock); rtg -- Tim Gardner tim.gardner@canonical.com