From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755114AbYFKHWR (ORCPT ); Wed, 11 Jun 2008 03:22:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753054AbYFKHWF (ORCPT ); Wed, 11 Jun 2008 03:22:05 -0400 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:45267 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752848AbYFKHWE (ORCPT ); Wed, 11 Jun 2008 03:22:04 -0400 Date: Wed, 11 Jun 2008 08:05:02 +0100 From: Alan Cox To: Tejun Heo Cc: Tejun Heo , James Bottomley , Jens Axboe , linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Prevent busy looping Message-ID: <20080611080502.4aa43980@core> In-Reply-To: <484F7A8D.1040809@gmail.com> References: <20080416151305.8788.63912.stgit@denkblock.local> <20080416163152.GK12774@kernel.dk> <87r6d5l9pb.fsf@denkblock.local> <20080417071335.GR12774@kernel.dk> <87ve2gc1bn.fsf@denkblock.local> <484F7A8D.1040809@gmail.com> X-Mailer: Claws Mail 3.3.1 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a Lloegr o'r rhif cofrestru 3798903 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Elias's synthetic test case triggered infinite loop because it wasn't > a proper ->qc_defer(). ->qc_defer() should never defer commands when > the target is idle. Target or host ? We *do* defer commands in the case of an idle channel when dealing with certain simplex controllers that can only issue one command per host not one per cable (and in fact in the general case we can defer commands due to activity on the other drive on the cable). Alan