scsi: st: fix blk_get_queue usage

If blk_queue_get() in st_probe fails, disk->queue must not be set to
SDp->request_queue, as that would result in put_disk() dropping a not
taken reference.

Thus, disk->queue should be set only after a successful blk_queue_get().

Fixes: 2b5bebccd282 ("st: Take additional queue ref in st_probe")
Signed-off-by: Bodo Stroesser <bstroesser@ts.fujitsu.com>
Acked-by: Shirish Pargaonkar <spargaonkar@suse.com>
Signed-off-by: Hannes Reinecke <hare@suse.com>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Acked-by: Kai Mäkisara <kai.makisara@kolumbus.fi>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/st.c

@@ -4299,11 +4299,11 @@ static int st_probe(struct device *dev)
 	kref_init(&tpnt->kref);
 	tpnt->disk = disk;
 	disk->private_data = &tpnt->driver;
-	disk->queue = SDp->request_queue;
 	/* SCSI tape doesn't register this gendisk via add_disk().  Manually
 	 * take queue reference that release_disk() expects. */
-	if (!blk_get_queue(disk->queue))
+	if (!blk_get_queue(SDp->request_queue))
 		goto out_put_disk;
+	disk->queue = SDp->request_queue;
 	tpnt->driver = &st_template;
 
 	tpnt->device = SDp;