- struct class_device *cdev, *next;
- struct unit_directory *ud;
-
- list_for_each_entry_safe(cdev, next, &nodemgr_ud_class.children, node) {
- ud = container_of(cdev, struct unit_directory, class_dev);
-
- if (ud->ne != ne)
- continue;
-
+ struct class_device *cdev;
+ struct unit_directory *tmp, *ud;
+
+ /* Iteration over nodemgr_ud_class.children has to be protected by
+ * nodemgr_ud_class.sem, but class_device_unregister() will eventually
+ * take nodemgr_ud_class.sem too. Therefore pick out one ud at a time,
+ * release the semaphore, and then unregister the ud. Since this code
+ * may be called from other contexts besides the knodemgrds, protect the
+ * gap after release of the semaphore by nodemgr_serialize_remove_uds.
+ */
+ mutex_lock(&nodemgr_serialize_remove_uds);
+ for (;;) {
+ ud = NULL;
+ down(&nodemgr_ud_class.sem);
+ list_for_each_entry(cdev, &nodemgr_ud_class.children, node) {
+ tmp = container_of(cdev, struct unit_directory,
+ class_dev);
+ if (tmp->ne == ne) {
+ ud = tmp;
+ break;
+ }
+ }
+ up(&nodemgr_ud_class.sem);
+ if (ud == NULL)
+ break;