linux-kernel - Re: [PATCH 1/2] scsi: Do not attach VPD to devices that don't support it

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Date:	Thu, 21 Jan 2016 08:37:11 +0100
From:	Hannes Reinecke <hare@...e.de>
To:	Alexander Duyck <aduyck@...antis.com>
Cc:	James Bottomley <James.Bottomley@...senPartnership.com>,
	linux-scsi@...r.kernel.org, alexander.duyck@...il.com,
	martin.petersen@...cle.com, linux-kernel@...r.kernel.org,
	shane.seymour@....com, jthumshirn@...e.de
Subject: Re: [PATCH 1/2] scsi: Do not attach VPD to devices that don't support
 it

On 01/21/2016 07:35 AM, Alexander Duyck wrote:
> The patch "scsi: rescan VPD attributes" introduced a regression in which
> devices that don't support VPD were being scanned for VPD attributes
> anyway.  This could cause issues for this parts and should be avoided so
> the check for scsi_level has been moved out of scsi_add_lun and into
> scsi_attach_vpd so that all callers will not scan VPD for devices that
> don't support it.
> 
> Fixes: 09e2b0b14690 ("scsi: rescan VPD attributes")
> Signed-off-by: Alexander Duyck <aduyck@...antis.com>
> ---
>  drivers/scsi/scsi.c      |    3 +++
>  drivers/scsi/scsi_scan.c |    3 +--
>  2 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
> index b1bf42b93fcc..ed085e78c893 100644
> --- a/drivers/scsi/scsi.c
> +++ b/drivers/scsi/scsi.c
> @@ -784,6 +784,9 @@ void scsi_attach_vpd(struct scsi_device *sdev)
>  	int pg83_supported = 0;
>  	unsigned char __rcu *vpd_buf, *orig_vpd_buf = NULL;
>  
> +	if (sdev->scsi_level < SCSI_3)
> +		return;
> +
>  	if (sdev->skip_vpd_pages)
>  		return;
>  retry_pg0:
> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> index 6a820668d442..1b16c89e0cf9 100644
> --- a/drivers/scsi/scsi_scan.c
> +++ b/drivers/scsi/scsi_scan.c
> @@ -986,8 +986,7 @@ static int scsi_add_lun(struct scsi_device *sdev, unsigned char *inq_result,
>  		}
>  	}
>  
> -	if (sdev->scsi_level >= SCSI_3)
> -		scsi_attach_vpd(sdev);
> +	scsi_attach_vpd(sdev);
>  
>  	sdev->max_queue_depth = sdev->queue_depth;
>  
> 
Isn't this slightly pointless, given that we're testing the inverse
condition in scsi_attach_vpd()?

And in anycase, I guess we should be using the same logic sd.c is
using. Please see the attached patch.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
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)

View attachment "0001-scsi-Do-not-attach-VPD-to-devices-that-don-t-support.patch" of type "text/x-patch" (3794 bytes)