Re: [PATCH 3/4] scsi_dh_rdac: Adding the match function for rdac device handler

[Hannes Reinecke <hare@suse.de>]

On 11/01/2011 06:19 PM, Moger, Babu wrote:
> This patch introduces the match function for rdac device handler. Without this,
> sometimes handler attach fails during the device_add.  The match function was
> introduced by this patch
> http://www.spinics.net/lists/linux-scsi/msg54284.html
>
> Signed-off-by: Babu Moger<babu.moger@netapp.com>
> ---
>
> --- linux/drivers/scsi/device_handler/scsi_dh_rdac.c.orig	2011-10-31 11:25:44.000000000 -0500
> +++ linux/drivers/scsi/device_handler/scsi_dh_rdac.c	2011-10-31 11:31:34.000000000 -0500
> @@ -819,6 +819,21 @@ static const struct scsi_dh_devlist rdac
>   	{NULL, NULL},
>   };
>
> +static bool rdac_match(struct scsi_device *sdev)
> +{
> +	int i;
> +
> +	for (i = 0; rdac_dev_list[i].vendor; i++) {
> +		if (!strncmp(sdev->vendor, rdac_dev_list[i].vendor,
> +			strlen(rdac_dev_list[i].vendor))&&
> +		    !strncmp(sdev->model, rdac_dev_list[i].model,
> +			strlen(rdac_dev_list[i].model))) {
> +			return true;
> +		}
> +	}
> +	return false;
> +}
> +
>   static int rdac_bus_attach(struct scsi_device *sdev);
>   static void rdac_bus_detach(struct scsi_device *sdev);
>
> @@ -831,6 +846,7 @@ static struct scsi_device_handler rdac_d
>   	.attach = rdac_bus_attach,
>   	.detach = rdac_bus_detach,
>   	.activate = rdac_activate,
> +	.match = rdac_match,
>   };
>
>   static int rdac_bus_attach(struct scsi_device *sdev)
>
As stated in the other mail, I guess we would need to have a check 
if the LUN is in ALUA mode.
And, btw, the _original_ intention was to allow vendor-specific 
device_handler to do some better probing, eg querying some 
vendor-specific VPD pages.
Especially for RDAC it would make far more sense to query the 
existence and format of one of the RDAC-specific VPD pages (eg 0xC2, 
0xC4, or 0xC8) and use that for matching.
Then you could do away with the vendor/model array altogether here 
and we wouldn't need to update the rdac handler every time a new 
array comes out or has been rebranded by some OEM.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
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