[SCSI] scsi_transport_spi: fix for unbalanced reference counting

Check the domain validation flag on the given device before referencing
scsi_device instance, otherwise if the flag is already set we return without
decrementing the reference count.
Signed-off-by: Mike Maslenkin <mihailm@parallels.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/scsi_transport_spi.c

@@ -1010,10 +1010,10 @@ spi_dv_device(struct scsi_device *sdev)
 	u8 *buffer;
 	const int len = SPI_MAX_ECHO_BUFFER_SIZE*2;
 
-	if (unlikely(scsi_device_get(sdev)))
+	if (unlikely(spi_dv_in_progress(starget)))
 		return;
 
-	if (unlikely(spi_dv_in_progress(starget)))
+	if (unlikely(scsi_device_get(sdev)))
 		return;
 	spi_dv_in_progress(starget) = 1;