+ /* A retaddr of zero is invalid so we really shouldn't have ended
+ * up here. The target code has likely forgotten to check retaddr
+ * != 0 before attempting to restore state. We return early to
+ * avoid blowing up on a recursive tb_lock(). The target must have
+ * previously survived a failed cpu_restore_state because
+ * tb_find_pc(0) would have failed anyway. It still should be
+ * fixed though.
+ */
+
+ if (!retaddr) {
+ return r;
+ }
+