+ * @rel: when @timer expires (relative).
+ *
+ * This efficiently adds @timer to @timers, to expire @rel (rounded to
+ * TIMER_GRANULARITY nanoseconds) after the current time. This
+ * is a convenient wrapper around timer_addmono().
+ *
+ * Example:
+ * // Timeout in 100ms.
+ * timer_addrel(&timeouts, &t, time_from_msec(100));
+ */
+void timer_addrel(struct timers *timers, struct timer *timer, struct timerel rel);
+
+/**
+ * timer_addmono - insert an absolute timer.
+ * @timers: the struct timers
+ * @timer: the (initialized or timer_del'd) timer to add
+ * @when: when @timer expires (absolute).