From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752592AbbJMLRM (ORCPT ); Tue, 13 Oct 2015 07:17:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41464 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752152AbbJMLRJ (ORCPT ); Tue, 13 Oct 2015 07:17:09 -0400 From: Vitaly Kuznetsov To: Hannes Reinecke Cc: "James E.J. Bottomley" , linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, "K. Y. Srinivasan" , Long Li , Dexuan Cui Subject: Re: [PATCH v3] scsi: report 'INQUIRY result too short' once per host References: <1444323291-16447-1-git-send-email-vkuznets@redhat.com> <561BA89B.2040504@suse.de> <87egh0yv5s.fsf@vitty.brq.redhat.com> <561CA1C6.2010207@suse.de> Date: Tue, 13 Oct 2015 13:17:05 +0200 In-Reply-To: <561CA1C6.2010207@suse.de> (Hannes Reinecke's message of "Tue, 13 Oct 2015 08:16:38 +0200") Message-ID: <87eggzxbke.fsf@vitty.brq.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hannes Reinecke writes: > On 10/12/2015 05:16 PM, Vitaly Kuznetsov wrote: >> Hannes Reinecke writes: >> >>> On 10/08/2015 06:54 PM, Vitaly Kuznetsov wrote: >>>> Some host adapters (e.g. Hyper-V storvsc) are known for not respecting the >>>> SPC-2/3/4 requirement for 'INQUIRY data (see table ...) shall contain at >>>> least 36 bytes'. As a result we get tons on 'scsi 0:7:1:1: scsi scan: >>>> INQUIRY result too short (5), using 36' messages on console. This can be >>>> problematic for slow consoles. Introduce short_inquiry flag in struct >>>> Scsi_Host to print the message once per host. >>>> >>>> Signed-off-by: Vitaly Kuznetsov >>>> --- >>>> Changes since v2: >>>> - This is a successor of previously sent (and still not merged) "scsi: >>>> introduce short_inquiry flag for broken host adapters" patch. I'm not >>>> particularly sure which solution is better but I'm leaning towards this >>>> one as it doesn't require changes to adapter drivers. >>>> --- >>>> drivers/scsi/scsi_scan.c | 9 ++++++--- >>>> include/scsi/scsi_host.h | 3 +++ >>>> 2 files changed, 9 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c >>>> index f9f3f82..cd347e4 100644 >>>> --- a/drivers/scsi/scsi_scan.c >>>> +++ b/drivers/scsi/scsi_scan.c >>>> @@ -701,9 +701,12 @@ static int scsi_probe_lun(struct scsi_device *sdev, unsigned char *inq_result, >>>> * strings. >>>> */ >>>> if (sdev->inquiry_len < 36) { >>>> - sdev_printk(KERN_INFO, sdev, >>>> - "scsi scan: INQUIRY result too short (%d)," >>>> - " using 36\n", sdev->inquiry_len); >>>> + if (!sdev->host->short_inquiry) { >>>> + shost_printk(KERN_INFO, sdev->host, >>>> + "scsi scan: INQUIRY result too short (%d)," >>>> + " using 36\n", sdev->inquiry_len); >>>> + sdev->host->short_inquiry = 1; >>>> + } >>>> sdev->inquiry_len = 36; >>>> } >>>> >>> At least you need to check if you've received any valid data here; >>> 'INQUIRY result too short' is also a common error if the interrupt >>> is hosed when trying to access the device. >>> So please check for 'inquiry_len > 4' before setting 'short_inquiry'. >> >> Currently we proceed even with a shorter reply... Should we abort the >> scan (and return -EOI?) in case we got inquiry_len <= 4? >> > Yes please. We need to ensure that we actually received some data, > and not running into an error scenario here. > So we need to read at least five bytes of data, as byte 4 carries > the response length. If we read less than that we have no way of > figuring out if the response data is even remotely sane. > I just checked and it seems such check would be redundant. inquiry_len is always >=5 as we have the following code: response_len = inq_result[4] + 5; where inq_result is unsigned char * After that we do: sdev->inquiry_len = min(try_inquiry_len, response_len); As far as I can see try_inquiry_len can be lower than 36 only in case some driver sets it manually. I don't see a '>=5' check for it but I'm not sure it is needed. -- Vitaly