ieee1394: lock smaller region by host_num_alloc mutex

We need the mutex only around the iteration over existing hosts.
Signed-off-by: NStefan Richter <stefanr@s5r6.in-berlin.de>

drivers/ieee1394/hosts.c

@@ -157,10 +157,9 @@ struct hpsb_host *hpsb_alloc_host(struct hpsb_host_driver *drv, size_t extra,
 	h->speed_map = (u8 *)(h->csr.speed_map + 2);
 
 	mutex_lock(&host_num_alloc);
-
 	while (nodemgr_for_each_host(&hostnum, alloc_hostnum_cb))
 		hostnum++;
-
+	mutex_unlock(&host_num_alloc);
 	h->id = hostnum;
 
 	memcpy(&h->device, &nodemgr_dev_template_host, sizeof(h->device));
@@ -175,8 +174,6 @@ struct hpsb_host *hpsb_alloc_host(struct hpsb_host_driver *drv, size_t extra,
 	class_device_register(&h->class_dev);
 	get_device(&h->device);
 
-	mutex_unlock(&host_num_alloc);
-
 	return h;
 }