1 files changed, 39 insertions, 0 deletions
diff --git a/sys/kern/kern_timeout.c b/sys/kern/kern_timeout.c
index 71c88e0..950cb0e 100644
--- a/sys/kern/kern_timeout.c
+++ b/sys/kern/kern_timeout.c
@@ -1145,6 +1145,45 @@ callout_schedule(struct callout *c, int to_ticks)
 }
 
 int
+callout_drain_async(struct callout *c, callout_func_t *func, void *arg)
+{
+	struct callout_cpu *cc;
+	struct lock_class *class;
+	int retval;
+	int direct;
+
+	/* stop callout */
+	callout_stop(c);
+
+	/* check if callback is being called */
+	cc = callout_lock(c);
+	if (c->c_iflags & CALLOUT_DIRECT) {
+		direct = 1;
+	} else {
+		direct = 0;
+	}
+	retval = (cc_exec_curr(cc, direct) == c);
+
+	/* drop locks, if any */
+	if (retval && c->c_lock != NULL &&
+	    c->c_lock != &Giant.lock_object) {
+		/* ensure we are properly locked */
+		class = LOCK_CLASS(c->c_lock);
+		class->lc_assert(c->c_lock, LA_XLOCKED);
+		/* the final callback should not be called locked */
+		c->c_lock = NULL;
+		c->c_iflags |= CALLOUT_RETURNUNLOCKED;
+	}
+	CC_UNLOCK(cc);
+
+	/* check if we should queue final callback */
+	if (retval)
+		callout_reset(c, 1, func, arg);
+
+	return (retval);
+}
+
+int
 _callout_stop_safe(struct callout *c, int safe)
 {
 	struct callout_cpu *cc, *old_cc;