Index: sys/arch/amd64/conf/GENERIC.MP
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/arch/amd64/conf/GENERIC.MP,v
diff -u -p -u -p -r1.16 GENERIC.MP
--- sys/arch/amd64/conf/GENERIC.MP	9 Feb 2021 14:06:19 -0000	1.16
+++ sys/arch/amd64/conf/GENERIC.MP	5 Dec 2023 23:58:23 -0000
@@ -4,6 +4,6 @@ include "arch/amd64/conf/GENERIC"
 
 option	MULTIPROCESSOR
 #option	MP_LOCKDEBUG
-#option	WITNESS
+option	WITNESS
 
 cpu*		at mainbus?
Index: sys/arch/arm64/conf/GENERIC.MP
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/arch/arm64/conf/GENERIC.MP,v
diff -u -p -u -p -r1.5 GENERIC.MP
--- sys/arch/arm64/conf/GENERIC.MP	1 Jul 2018 21:05:07 -0000	1.5
+++ sys/arch/arm64/conf/GENERIC.MP	5 Dec 2023 23:58:23 -0000
@@ -4,6 +4,6 @@ include "arch/arm64/conf/GENERIC"
 
 option	MULTIPROCESSOR
 #option	MP_LOCKDEBUG
-#option	WITNESS
+option	WITNESS
 
 cpu*		at mainbus?
Index: sys/arch/i386/conf/GENERIC.MP
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/arch/i386/conf/GENERIC.MP,v
diff -u -p -u -p -r1.11 GENERIC.MP
--- sys/arch/i386/conf/GENERIC.MP	3 Jun 2018 05:18:33 -0000	1.11
+++ sys/arch/i386/conf/GENERIC.MP	5 Dec 2023 23:58:23 -0000
@@ -7,6 +7,6 @@ include "arch/i386/conf/GENERIC"
 
 option		MULTIPROCESSOR	# Multiple processor support
 #option		MP_LOCKDEBUG
-#option		WITNESS
+option		WITNESS
 
 cpu*		at mainbus?
Index: sys/arch/macppc/conf/GENERIC.MP
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/arch/macppc/conf/GENERIC.MP,v
diff -u -p -u -p -r1.2 GENERIC.MP
--- sys/arch/macppc/conf/GENERIC.MP	15 Apr 2020 08:09:33 -0000	1.2
+++ sys/arch/macppc/conf/GENERIC.MP	5 Dec 2023 23:58:23 -0000
@@ -4,6 +4,6 @@ include "arch/macppc/conf/GENERIC"
 
 option	MULTIPROCESSOR
 #option	MP_LOCKDEBUG
-#option	WITNESS
+option	WITNESS
 
 cpu*	at mainbus?
Index: sys/arch/powerpc64/conf/GENERIC.MP
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/arch/powerpc64/conf/GENERIC.MP,v
diff -u -p -u -p -r1.1 GENERIC.MP
--- sys/arch/powerpc64/conf/GENERIC.MP	21 Jul 2020 21:38:31 -0000	1.1
+++ sys/arch/powerpc64/conf/GENERIC.MP	5 Dec 2023 23:58:23 -0000
@@ -4,6 +4,6 @@ include "arch/powerpc64/conf/GENERIC"
 
 option	MULTIPROCESSOR
 #option	MP_LOCKDEBUG
-#option	WITNESS
+option	WITNESS
 
 cpu*		at mainbus?
Index: sys/arch/riscv64/conf/GENERIC.MP
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/arch/riscv64/conf/GENERIC.MP,v
diff -u -p -u -p -r1.1 GENERIC.MP
--- sys/arch/riscv64/conf/GENERIC.MP	29 Jun 2021 21:27:52 -0000	1.1
+++ sys/arch/riscv64/conf/GENERIC.MP	5 Dec 2023 23:58:23 -0000
@@ -4,6 +4,6 @@ include "arch/riscv64/conf/GENERIC"
 
 option	MULTIPROCESSOR
 #option	MP_LOCKDEBUG
-#option	WITNESS
+option	WITNESS
 
 cpu*		at mainbus?
Index: sys/netinet/ip_mroute.c
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/netinet/ip_mroute.c,v
diff -u -p -u -p -r1.139 ip_mroute.c
--- sys/netinet/ip_mroute.c	14 Jun 2023 14:30:08 -0000	1.139
+++ sys/netinet/ip_mroute.c	5 Dec 2023 23:58:17 -0000
@@ -1048,11 +1048,18 @@ del_mfc(struct socket *so, struct mbuf *
 }
 
 int
-socket_send(struct socket *s, struct mbuf *mm, struct sockaddr_in *src)
+socket_send(struct socket *so, struct mbuf *mm, struct sockaddr_in *src)
 {
-	if (s != NULL) {
-		if (sbappendaddr(s, &s->so_rcv, sintosa(src), mm, NULL) != 0) {
-			sorwakeup(s);
+	if (so != NULL) {
+		struct inpcb *inp = sotoinpcb(so);
+		int ret;
+
+		mtx_enter(&inp->inp_mtx);
+		ret = sbappendaddr(so, &so->so_rcv, sintosa(src), mm, NULL);
+		mtx_leave(&inp->inp_mtx);
+
+		if (ret != 0) {
+			sorwakeup(so);
 			return (0);
 		}
 	}
Index: sys/netinet6/ip6_mroute.c
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/netinet6/ip6_mroute.c,v
diff -u -p -u -p -r1.137 ip6_mroute.c
--- sys/netinet6/ip6_mroute.c	14 Jun 2023 14:30:08 -0000	1.137
+++ sys/netinet6/ip6_mroute.c	5 Dec 2023 23:58:17 -0000
@@ -853,11 +853,18 @@ del_m6fc(struct socket *so, struct mf6cc
 }
 
 int
-socket6_send(struct socket *s, struct mbuf *mm, struct sockaddr_in6 *src)
+socket6_send(struct socket *so, struct mbuf *mm, struct sockaddr_in6 *src)
 {
-	if (s) {
-		if (sbappendaddr(s, &s->so_rcv, sin6tosa(src), mm, NULL) != 0) {
-			sorwakeup(s);
+	if (so != NULL) {
+		struct inpcb *inp = sotoinpcb(so);
+		int ret;
+
+		mtx_enter(&inp->inp_mtx);
+		ret = sbappendaddr(so, &so->so_rcv, sin6tosa(src), mm, NULL);
+		mtx_leave(&inp->inp_mtx);
+
+		if (ret != 0) {
+			sorwakeup(so);
 			return 0;
 		}
 	}