Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758854AbYAFQUF (ORCPT ); Sun, 6 Jan 2008 11:20:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754239AbYAFQT4 (ORCPT ); Sun, 6 Jan 2008 11:19:56 -0500 Received: from gw-colo-pa.panasas.com ([66.238.117.130]:25626 "EHLO cassoulet.panasas.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754209AbYAFQTz (ORCPT ); Sun, 6 Jan 2008 11:19:55 -0500 Message-ID: <4780FF85.4020501@panasas.com> Date: Sun, 06 Jan 2008 18:19:17 +0200 From: Boaz Harrosh User-Agent: Thunderbird 2.0.0.9 (X11/20071031) MIME-Version: 1.0 To: James Bottomley , Matthew Wilcox CC: Linus Torvalds , Peter Osterlund , Ingo Molnar , Linux Kernel Mailing List , Andrew Morton , Jens Axboe , Al Viro Subject: Re: [patch] scsi: revert "[SCSI] Get rid of scsi_cmnd->done" References: <20080102162534.GA4041@elte.hu> <1199292381.3258.32.camel@localhost.localdomain> <20080102194030.GC11638@parisc-linux.org> <1199304735.3258.53.camel@localhost.localdomain> <1199316785.3258.85.camel@localhost.localdomain> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 06 Jan 2008 16:19:22.0955 (UTC) FILETIME=[E5FAD9B0:01C8507F] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1340 Lines: 33 On Sun, Jan 06 2008 at 5:43 +0200, Linus Torvalds wrote: > > > This all still leaves the question unanswered why that commit > 6f5391c283d7fdcf24bf40786ea79061919d1e1d changed any behaviour at all. > Because the thing that Peter is describing has nothing to do with any > low-level drivers what-so-ever. > > Linus > James Matthew. I have a (very) wild guess at what maybe have changed with the cmnd->done patch: Do you remember the effective loop in scsi_lib:scsi_end_request() where if bufflen was smaller then original request size, do to truncation of bufflen by ULD, then the remaining of the request is re-queued again as a new scsi-command. Well I think that the old system would call cmnd->done for every iteration, and the new system, since the done is called by the block-Q, does not see the resubmit of the new command. I have not followed all code path of the matter, but I know that sr does alters bufflen in some cases. All this is not a bug in itself, but it is a change in behavior that might cause the current sr hack to fail. Boaz -- 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/