From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754741AbYFKIEF (ORCPT ); Wed, 11 Jun 2008 04:04:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753841AbYFKIDn (ORCPT ); Wed, 11 Jun 2008 04:03:43 -0400 Received: from rv-out-0506.google.com ([209.85.198.226]:48299 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753317AbYFKIDk (ORCPT ); Wed, 11 Jun 2008 04:03:40 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:x-enigmail-version:content-type :content-transfer-encoding; b=M6AHsPS7ALIplf+JVdiL5t2iQdRGZPVZFEYArzHu19LPg4H/kQzJG+SwsGX24C0UXB QU3pxSFBPWWxrNCsWYuRQHKXcsbkVS+Ut+K+jgXbeDF2fMNnNC2avne0eIzKg4tHlZNp OEMehUonrQwxjnEhecVHIPK6JS7oDCWtQmVTo= Message-ID: <484F86D4.8050907@gmail.com> Date: Wed, 11 Jun 2008 17:03:32 +0900 From: Tejun Heo User-Agent: Thunderbird 2.0.0.12 (X11/20080226) MIME-Version: 1.0 To: Alan Cox CC: James Bottomley , Jens Axboe , linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Prevent busy looping 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> <20080611080502.4aa43980@core> In-Reply-To: <20080611080502.4aa43980@core> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Alan Cox wrote: >> 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). The term was confusing. I used target to mean both device (ATA_DEFER_LINK) and host (ATA_DEFER_PORT). Hmmm... in simplex case, yeah, blocked counters need to be > 1. We'll need to increase blocked counts after all. I'll test blocked counts of 2 w/ PMP and make sure it doesn't incur unnecessary delays and post the patch. Thanks. -- tejun