Index: uspace/lib/c/generic/loc.c
===================================================================
--- uspace/lib/c/generic/loc.c	(revision 88057e3e2bdf0d2bd3fdb2418dc8268527b72c2b)
+++ uspace/lib/c/generic/loc.c	(revision a6240a31de71ce1b22250da6712a30e0ca520c66)
@@ -47,4 +47,5 @@
 static FIBRIL_MUTEX_INITIALIZE(loc_callback_mutex);
 static bool loc_callback_created = false;
+static loc_cat_change_cb_t cat_change_cb = NULL;
 
 static async_sess_t *loc_supp_block_sess = NULL;
@@ -54,10 +55,6 @@
 static async_sess_t *loc_consumer_sess = NULL;
 
-static loc_cat_change_cb_t cat_change_cb = NULL;
-
 static void loc_cb_conn(ipc_callid_t iid, ipc_call_t *icall, void *arg)
 {
-	loc_cat_change_cb_t cb_fun;
-	
 	while (true) {
 		ipc_call_t call;
@@ -69,21 +66,19 @@
 		}
 		
-		int retval;
-		
 		switch (IPC_GET_IMETHOD(call)) {
 		case LOC_EVENT_CAT_CHANGE:
 			fibril_mutex_lock(&loc_callback_mutex);
-			cb_fun = cat_change_cb;
-			if (cb_fun != NULL) {
+			loc_cat_change_cb_t cb_fun = cat_change_cb;
+			fibril_mutex_unlock(&loc_callback_mutex);
+			
+			async_answer_0(callid, EOK);
+			
+			if (cb_fun != NULL)
 				(*cb_fun)();
-			}
-			fibril_mutex_unlock(&loc_callback_mutex);
-			retval = 0;
+			
 			break;
 		default:
-			retval = ENOTSUP;
+			async_answer_0(callid, ENOTSUP);
 		}
-		
-		async_answer_0(callid, retval);
 	}
 }
@@ -101,14 +96,16 @@
 }
 
+/** Create callback
+ *
+ * Must be called with loc_callback_mutex locked.
+ *
+ * @return EOK on success.
+ *
+ */
 static int loc_callback_create(void)
 {
-	async_exch_t *exch;
-	sysarg_t retval;
-	int rc = EOK;
-
-	fibril_mutex_lock(&loc_callback_mutex);
-	
 	if (!loc_callback_created) {
-		exch = loc_exchange_begin_blocking(LOC_PORT_CONSUMER);
+		async_exch_t *exch =
+		    loc_exchange_begin_blocking(LOC_PORT_CONSUMER);
 		
 		ipc_call_t answer;
@@ -117,7 +114,6 @@
 		loc_exchange_end(exch);
 		
-		async_wait_for(req, &retval);
 		if (rc != EOK)
-			goto done;
+			return rc;
 		
 		if (retval != EOK) {
@@ -129,8 +125,5 @@
 	}
 	
-	rc = EOK;
-done:
-	fibril_mutex_unlock(&loc_callback_mutex);
-	return rc;
+	return EOK;
 }
 
@@ -861,8 +854,13 @@
 int loc_register_cat_change_cb(loc_cat_change_cb_t cb_fun)
 {
-	if (loc_callback_create() != EOK)
+	fibril_mutex_lock(&loc_callback_mutex);
+	if (loc_callback_create() != EOK) {
+		fibril_mutex_unlock(&loc_callback_mutex);
 		return EIO;
-
+	}
+	
 	cat_change_cb = cb_fun;
+	fibril_mutex_unlock(&loc_callback_mutex);
+	
 	return EOK;
 }