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



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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