2 files changed, 21 insertions, 1 deletions

diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile
index fb010231d710..52a5d373a417 100644
--- a/share/man/man9/Makefile
+++ b/share/man/man9/Makefile
@@ -859,6 +859,7 @@ MLINKS+=condvar.9 cv_broadcast.9 \
 	condvar.9 cv_wait_unlock.9 \
 	condvar.9 cv_wmesg.9
 MLINKS+=config_intrhook.9 config_intrhook_disestablish.9 \
+	config_intrhook.9 config_intrhook_drain.9 \
 	config_intrhook.9 config_intrhook_establish.9 \
 	config_intrhook.9 config_intrhook_oneshot.9
 MLINKS+=contigmalloc.9 contigmalloc_domainset.9 \
diff --git a/share/man/man9/config_intrhook.9 b/share/man/man9/config_intrhook.9
index 0414ad88218a..6892a089b00f 100644
--- a/share/man/man9/config_intrhook.9
+++ b/share/man/man9/config_intrhook.9
@@ -26,7 +26,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd August 10, 2017
+.Dd March 8, 2021
 .Dt CONFIG_INTRHOOK 9
 .Os
 .Sh NAME
@@ -40,6 +40,8 @@ but before root is mounted
 .Fn config_intrhook_establish "struct intr_config_hook *hook"
 .Ft void
 .Fn config_intrhook_disestablish "struct intr_config_hook *hook"
+.Ft int
+.Fn config_intrhook_drain "struct intr_config_hook *hook"
 .Ft void
 .Fn config_intrhook_oneshot "ich_func_t func" "void *arg"
 .Sh DESCRIPTION
@@ -55,6 +57,23 @@ The
 function removes the entry from the hook queue.
 .Pp
 The
+.Fn config_intrhook_drain
+function removes the entry from the hook queue in a safe way.
+If the hook is not currently active it removes
+.Fa hook
+from the hook queue and returns
+.Vt ICHS_QUEUED .
+If the hook is active, it waits for the hook to complete before returning
+.Vt ICHS_RUNNING .
+If the hook has previously completed, it returns
+.Vt ICHS_DONE .
+Because a
+.Vt config_intrhook
+is undefined prior to
+.Fn config_intrhook_establish ,
+this function may only be called after that function has returned.
+.Pp
+The
 .Fn config_intrhook_oneshot
 function schedules a function to be run as described for
 .Fn config_intrhook_establish ;