Lock the linked list mutex when accessing the memory handles. This should fix the invalid values appearing for short times in the buffering debug screen.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@17497 a1c6a512-1295-4272-9138-f99709370657

apps/buffering.c

@@ -522,6 +522,8 @@ static void update_data_counters(void)
     size_t remaining = 0;
     size_t useful = 0;
 
+    mutex_lock(&llist_mutex);
+
     m = first_handle;
     while (m) {
         buffered += m->available;
@@ -537,6 +539,8 @@ static void update_data_counters(void)
         m = m->next;
     }
 
+    mutex_unlock(&llist_mutex);
+
     data_counters.buffered = buffered;
     data_counters.wasted = wasted;
     data_counters.remaining = remaining;