linux-kernel - Re: [PATCH v3] scsi: report 'INQUIRY result too short' once per host

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Date:	Mon, 12 Oct 2015 14:33:31 +0200
From:	Hannes Reinecke <hare@...e.de>
To:	Vitaly Kuznetsov <vkuznets@...hat.com>,
	"James E.J. Bottomley" <JBottomley@...n.com>
CC:	linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Long Li <longli@...rosoft.com>,
	Dexuan Cui <decui@...rosoft.com>
Subject: Re: [PATCH v3] scsi: report 'INQUIRY result too short' once per host

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 <vkuznets@...hat.com>
> ---
> 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'.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		               zSeries & Storage
hare@...e.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
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