[SCSI] sg: set class_data after success

If cdev_add fails in sg_add, sg_remove crashes since class_data is
bogus.
Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: NDouglas Gilbert <dougg@torque.net>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/sg.c

@@ -1422,7 +1422,6 @@ sg_add(struct class_device *cl_dev, struct class_interface *cl_intf)
 		goto out;
 	}
 
-	class_set_devdata(cl_dev, sdp);
 	error = cdev_add(cdev, MKDEV(SCSI_GENERIC_MAJOR, sdp->index), 1);
 	if (error)
 		goto cdev_add_err;
@@ -1451,6 +1450,8 @@ sg_add(struct class_device *cl_dev, struct class_interface *cl_intf)
 		    "Attached scsi generic sg%d type %d\n", sdp->index,
 		    scsidp->type);
 
+	class_set_devdata(cl_dev, sdp);
+
 	return 0;
 
 cdev_add_err: