Index: share/man/man9/Makefile
===================================================================
--- share/man/man9/Makefile
+++ share/man/man9/Makefile
@@ -1367,6 +1367,7 @@
 	kqueue.9 knlist_init.9 \
 	kqueue.9 knlist_init_mtx.9 \
 	kqueue.9 knlist_init_rw_reader.9 \
+	kqueue.9 knlist_init_sx.9 \
 	kqueue.9 knlist_remove.9 \
 	kqueue.9 knlist_remove_inevent.9 \
 	kqueue.9 knote_fdclose.9 \
Index: share/man/man9/kqueue.9
===================================================================
--- share/man/man9/kqueue.9
+++ share/man/man9/kqueue.9
@@ -24,14 +24,14 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd October 12, 2021
+.Dd July 24, 2022
 .Dt KQUEUE 9
 .Os
 .Sh NAME
 .Nm kqueue_add_filteropts , kqueue_del_filteropts ,
 .Nm kqfd_register ,
 .Nm knote_fdclose ,
-.Nm knlist_init , knlist_init_mtx , knlist_init_rw_reader ,
+.Nm knlist_init , knlist_init_mtx , knlist_init_rw_reader , knlist_init_sx ,
 .Nm knlist_add , knlist_remove , knlist_remove_inevent , knlist_empty ,
 .Nm knlist_clear , knlist_delete , knlist_destroy ,
 .Nm KNOTE_LOCKED , KNOTE_UNLOCKED
@@ -59,6 +59,8 @@
 .Ft void
 .Fn knlist_init_rw_reader "struct knlist *knl" "struct rwlock *lock"
 .Ft void
+.Fn knlist_init_sx "struct knlist *knl" "struct sx *lock"
+.Ft void
 .Fn knlist_add "struct knlist *knl" "struct knote *kn" "int islocked"
 .Ft void
 .Fn knlist_remove "struct knlist *knl" "struct knote *kn" "int islocked"
@@ -261,9 +263,10 @@
 .Vt knlist
 must be initialized with either
 .Fn knlist_init ,
-.Fn knlist_init_mtx
+.Fn knlist_init_mtx ,
+.Fn knlist_init_rw_reader
 or
-.Fn knlist_init_rw_reader .
+.Fn knlist_init_sx .
 The
 .Vt knlist
 structure may be embedded into the object structure.
@@ -321,6 +324,16 @@
 function.
 .Pp
 The function
+.Fn knlist_init_sx
+may be used to initialize a
+.Vt knlist
+when
+.Fa lock
+is a
+.Xr sx 9
+lock.
+.Pp
+The function
 .Fn knlist_empty
 returns true when there are no
 .Vt knotes
Index: sys/kern/kern_event.c
===================================================================
--- sys/kern/kern_event.c
+++ sys/kern/kern_event.c
@@ -2535,6 +2535,30 @@
 		rw_assert((struct rwlock *)arg, RA_UNLOCKED);
 }
 
+static void
+knlist_sx_xlock(void *arg)
+{
+
+	sx_xlock((struct sx *)arg);
+}
+
+static void
+knlist_sx_xunlock(void *arg)
+{
+
+	sx_xunlock((struct sx *)arg);
+}
+
+static void
+knlist_sx_assert_lock(void *arg, int what)
+{
+
+	if (what == LA_LOCKED)
+		sx_assert((struct sx *)arg, SX_LOCKED);
+	else
+		sx_assert((struct sx *)arg, SX_UNLOCKED);
+}
+
 void
 knlist_init(struct knlist *knl, void *lock, void (*kl_lock)(void *),
     void (*kl_unlock)(void *),
@@ -2588,6 +2612,14 @@
 	    knlist_rw_assert_lock);
 }
 
+void
+knlist_init_sx(struct knlist *knl, struct sx *lock)
+{
+
+	knlist_init(knl, lock, knlist_sx_xlock, knlist_sx_xunlock,
+	    knlist_sx_assert_lock);
+}
+
 void
 knlist_destroy(struct knlist *knl)
 {
Index: sys/sys/event.h
===================================================================
--- sys/sys/event.h
+++ sys/sys/event.h
@@ -326,6 +326,7 @@
 struct knlist;
 struct mtx;
 struct rwlock;
+struct sx;
 
 void	knote(struct knlist *list, long hint, int lockflags);
 void	knote_fork(struct knlist *list, int pid);
@@ -338,6 +339,7 @@
 	    void (*kl_unlock)(void *), void (*kl_assert_lock)(void *, int));
 void	knlist_init_mtx(struct knlist *knl, struct mtx *lock);
 void	knlist_init_rw_reader(struct knlist *knl, struct rwlock *lock);
+void	knlist_init_sx(struct knlist *knl, struct sx *lock);
 void	knlist_destroy(struct knlist *knl);
 void	knlist_cleardel(struct knlist *knl, struct thread *td,
 	    int islocked, int killkn);