[SCSI] libsas: sas_rediscover_dev did not look at the SMP exec status.

The discovery function "sas_rediscover_dev" had two bugs: 1) it did
not pay attention to the return status from the SMP task execution;
2) the stack variable used for the returned SAS address was compared
against 0 without being initialized.

Signed-off-by: Jeff Skirvin <[e-mail]>
Signed-off-by: Dan Williams <[e-mail]>
Signed-off-by: James Bottomley <[e-mail]>

drivers/scsi/libsas/sas_expander.c

···
 	u8 sas_addr[8];
 	int res;
 
+	memset(sas_addr, 0, 8);
 	res = sas_get_phy_attached_dev(dev, phy_id, sas_addr, &type);
 	switch (res) {
 	case SMP_RESP_NO_PHY:
···
 		return res;
 	case SMP_RESP_FUNC_ACC:
 		break;
+	case -ECOMM:
+		break;
+	default:
+		return res;
 	}
 
-	if (SAS_ADDR(sas_addr) == 0) {
+	if ((SAS_ADDR(sas_addr) == 0) || (res == -ECOMM)) {
 		phy->phy_state = PHY_EMPTY;
 		sas_unregister_devs_sas_addr(dev, phy_id, last);
 		return res;