[SCSI] fix bsg queue oops with iscsi logout

Delay bsg unregistration, because we want to wait until all the request/cmds
have released their reference.
Signed-off-by: NMike Christie <michaelc@cs.wisc.edu>
Acked-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/scsi_sysfs.c

@@ -294,6 +294,7 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
 	}
 
 	if (sdev->request_queue) {
+		bsg_unregister_queue(sdev->request_queue);
 		sdev->request_queue->queuedata = NULL;
 		/* user context needed to free queue */
 		scsi_free_queue(sdev->request_queue);
@@ -857,7 +858,6 @@ void __scsi_remove_device(struct scsi_device *sdev)
 	if (scsi_device_set_state(sdev, SDEV_CANCEL) != 0)
 		return;
 
-	bsg_unregister_queue(sdev->request_queue);
 	class_device_unregister(&sdev->sdev_classdev);
 	transport_remove_device(dev);
 	device_del(dev);