SCSI fixes on 20150314

This is a simple fix for a domain revalidation crash which has recently turned
 up in the libsas code (applies to mvsas, isc and aic94xx).
 
 Signed-off-by: James Bottomley <JBottomley@Parallels.com>
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Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

Pull SCSI fix from James Bottomley:
 "This is a simple fix for a domain revalidation crash which has
  recently turned up in the libsas code (applies to mvsas, isc and
  aic94xx)"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  libsas: Fix Kernel Crash in smp_execute_task

drivers/scsi/libsas/sas_discover.c

@@ -500,6 +500,7 @@ static void sas_revalidate_domain(struct work_struct *work)
 	struct sas_discovery_event *ev = to_sas_discovery_event(work);
 	struct asd_sas_port *port = ev->port;
 	struct sas_ha_struct *ha = port->ha;
+	struct domain_device *ddev = port->port_dev;
 
 	/* prevent revalidation from finding sata links in recovery */
 	mutex_lock(&ha->disco_mutex);
@@ -514,8 +515,9 @@ static void sas_revalidate_domain(struct work_struct *work)
 	SAS_DPRINTK("REVALIDATING DOMAIN on port %d, pid:%d\n", port->id,
 		    task_pid_nr(current));
 
-	if (port->port_dev)
-		res = sas_ex_revalidate_domain(port->port_dev);
+	if (ddev && (ddev->dev_type == SAS_FANOUT_EXPANDER_DEVICE ||
+		     ddev->dev_type == SAS_EDGE_EXPANDER_DEVICE))
+		res = sas_ex_revalidate_domain(ddev);
 
 	SAS_DPRINTK("done REVALIDATING DOMAIN on port %d, pid:%d, res 0x%x\n",
 		    port->id, task_pid_nr(current), res);