Add iomux_from_timers() function to recover an IOMux from

the associated UCTimers

include/ucore/iomux.h

@@ -132,6 +132,11 @@ int iomux_update_events(struct IOMux *mux, struct IOMuxFD *fd, unsigned int what
  */
 struct UCTimers *iomux_get_timers(struct IOMux *mux);
 
+/** Given an UCTimers associated with an IOMux, return the associated IOMux.
+ * (the UCTimers must previously been obtained from iomux_get_timers directly,
+ * or indirectly by the UCTimers provieded in a timer callback handler.
+ */
+struct IOMux *iomux_from_timers(struct UCTimers *timers);
 #ifdef __cplusplus
 }
 #endif