From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 95813C433E0 for ; Tue, 21 Jul 2020 06:38:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 77C7520658 for ; Tue, 21 Jul 2020 06:38:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728212AbgGUGi4 (ORCPT ); Tue, 21 Jul 2020 02:38:56 -0400 Received: from mx2.suse.de ([195.135.220.15]:43924 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726053AbgGUGiz (ORCPT ); Tue, 21 Jul 2020 02:38:55 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 46337ACDB; Tue, 21 Jul 2020 06:39:00 +0000 (UTC) Subject: Re: [PATCH v2 24/24] scsi: aic7xxx: aic79xx_osm: Remove set but unused variabes 'saved_scsiid' and 'saved_modes' To: jejb@linux.ibm.com, Lee Jones Cc: martin.petersen@oracle.com, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, Hannes Reinecke References: <20200713080001.128044-1-lee.jones@linaro.org> <20200713080001.128044-25-lee.jones@linaro.org> <559e47de-fa26-9ae5-a3c5-4adeae606309@suse.de> <1594741430.4545.15.camel@linux.ibm.com> <20200714213951.GL1398296@dell> <1594767794.14804.21.camel@linux.ibm.com> From: Hannes Reinecke Message-ID: <6cc1f2fe-ae61-2a54-89df-35d994dc388b@suse.de> Date: Tue, 21 Jul 2020 08:38:51 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <1594767794.14804.21.camel@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/15/20 1:03 AM, James Bottomley wrote: > On Tue, 2020-07-14 at 22:39 +0100, Lee Jones wrote: >> On Tue, 14 Jul 2020, James Bottomley wrote: >> >>> On Tue, 2020-07-14 at 09:46 +0200, Hannes Reinecke wrote: >>>> On 7/13/20 10:00 AM, Lee Jones wrote: >>>>> Haven't been used since 2006. >>>>> >>>>> Fixes the following W=1 kernel build warning(s): >>>>> >>>>> drivers/scsi/aic7xxx/aic79xx_osm.c: In function >>>>> ‘ahd_linux_queue_abort_cmd’: >>>>> drivers/scsi/aic7xxx/aic79xx_osm.c:2155:17: warning: variable >>>>> ‘saved_modes’ set but not used [-Wunused-but-set-variable] >>>>> drivers/scsi/aic7xxx/aic79xx_osm.c:2148:9: warning: variable >>>>> ‘saved_scsiid’ set but not used [-Wunused-but-set-variable] >>>>> >>>>> Cc: Hannes Reinecke >>>>> Signed-off-by: Lee Jones >>>>> --- >>>>> drivers/scsi/aic7xxx/aic79xx_osm.c | 4 ---- >>>>> 1 file changed, 4 deletions(-) >>>>> >>>>> diff --git a/drivers/scsi/aic7xxx/aic79xx_osm.c >>>>> b/drivers/scsi/aic7xxx/aic79xx_osm.c >>>>> index 3782a20d58885..140c4e74ddd7e 100644 >>>>> --- a/drivers/scsi/aic7xxx/aic79xx_osm.c >>>>> +++ b/drivers/scsi/aic7xxx/aic79xx_osm.c >>>>> @@ -2141,14 +2141,12 @@ ahd_linux_queue_abort_cmd(struct >>>>> scsi_cmnd >>>>> *cmd) >>>>> u_int saved_scbptr; >>>>> u_int active_scbptr; >>>>> u_int last_phase; >>>>> - u_int saved_scsiid; >>>>> u_int cdb_byte; >>>>> int retval; >>>>> int was_paused; >>>>> int paused; >>>>> int wait; >>>>> int disconnected; >>>>> - ahd_mode_state saved_modes; >>>>> unsigned long flags; >>>>> >>>>> pending_scb = NULL; >>>>> @@ -2239,7 +2237,6 @@ ahd_linux_queue_abort_cmd(struct >>>>> scsi_cmnd >>>>> *cmd) >>>>> goto done; >>>>> } >>>>> >>>>> - saved_modes = ahd_save_modes(ahd); >>>>> ahd_set_modes(ahd, AHD_MODE_SCSI, AHD_MODE_SCSI); >>>>> last_phase = ahd_inb(ahd, LASTPHASE); >>>>> saved_scbptr = ahd_get_scbptr(ahd); >>>>> @@ -2257,7 +2254,6 @@ ahd_linux_queue_abort_cmd(struct >>>>> scsi_cmnd >>>>> *cmd) >>>>> * passed in command. That command is currently >>>>> active on >>>>> the >>>>> * bus or is in the disconnected state. >>>>> */ >>>>> - saved_scsiid = ahd_inb(ahd, SAVED_SCSIID); >>>>> if (last_phase != P_BUSFREE >>>>> && SCB_GET_TAG(pending_scb) == active_scbptr) { >>>>> >>>>> >>>> >>>> Reviewed-by: Hannes Reinecke >>> >>> Hey, you don't get to do that ... I asked you to figure out why >>> we're missing an ahd_restore_modes(). Removing the >>> ahd_save_modes() is cosmetic: it gets rid of a warning but doesn't >>> fix the problem. I'd rather keep the warning until the problem is >>> fixed and the problem is we need a mode save/restore around the >>> ahd_set_modes() which is only partially implemented in this >>> function. >> >> I had a look. Traced it back to the dawn of time (time == Git), then >> delved even further back by downloading and trawling through ~10-15 >> tarballs. It looks as though drivers/scsi/aic7xxx/aic79xx_osm.c was >> upstreamed in v2.5.60, nearly 20 years ago. 'saved_modes' has been >> unused since at least then. If no one has complained in 2 decades, >> I'd say it probably isn't an issue worth perusing. > > Well, we have what looks like a fix now. The reason it matters is that > if the bus is not in AHD_MODE_SCSI when the routine is called, it ends > up being in a wrong state when the routine exits, so you abort one > command and screw up another. Ultimately I bet escalation to bus reset > fixes it, so everything appears to work, but it might have worked a lot > better if the original mode were restored. > > This is error handling code, so most installations run just fine > without ever invoking it. > And since you mention it, it might also explain why every time this routine got invoked it failed to fixup anything and got escalated to bus reset. (And yes, I _did_ have some customer issues with aic79xx EH escalations over the years). Testing will be tricky, though, as you'd have to inject timeouts onto the parallel bus or device. Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer