From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753493AbaE0Sy2 (ORCPT ); Tue, 27 May 2014 14:54:28 -0400 Received: from mail-pa0-f46.google.com ([209.85.220.46]:41566 "EHLO mail-pa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753479AbaE0SyY (ORCPT ); Tue, 27 May 2014 14:54:24 -0400 Message-ID: <5384DF5E.3020304@kernel.dk> Date: Tue, 27 May 2014 12:54:22 -0600 From: Jens Axboe User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Christoph Hellwig CC: Ming Lei , Linux Kernel Mailing List , stable Subject: Re: [PATCH] block: mq flush: fix race between IPI handler and mq flush worker References: <1400511950-18522-1-git-send-email-tom.leiming@gmail.com> <20140519151824.GA21762@lst.de> <20140520152303.GA20352@lst.de> <20140521053634.GA4764@lst.de> <20140527181305.GA7975@lst.de> <5384DB97.70606@kernel.dk> <20140527185301.GA8466@lst.de> In-Reply-To: <20140527185301.GA8466@lst.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014-05-27 12:53, Christoph Hellwig wrote: > On Tue, May 27, 2014 at 12:38:15PM -0600, Jens Axboe wrote: >> On 2014-05-27 12:13, Christoph Hellwig wrote: >>> Here is my counter proposal that requeues via two lists and a work struct >>> in the request_queue. I've also tested it with scsi-mq. >>> >> >> I like this, moves the state out of the request. But how about we >> consolidate the two requeue requests lists, and just mark the request as >> needing head insertion instead? Just add a cmd_flags flag, REQ_REQUEUE_HEAD >> or something. > > That should be doable, just didn't like introducing even more flags. Space is plenty big again now... The down side is that the splice trick wont work, but if we have more than a few requests on the requeue list, we're doing it wrong anyway. -- Jens Axboe