Each of them is the only IGMPCTL_STATS, PFSYNCCTL_STATS and
RIPV6CTL_STATS per-CPU counters.

sysctl_rdstruct() has "newp != NULL" check within and also returns
EPERM, no need for redundant check in igmp_sysctl().

ok?

Index: sys/netinet/igmp.c
===================================================================
RCS file: /cvs/src/sys/netinet/igmp.c,v
diff -u -p -r1.84 igmp.c
--- sys/netinet/igmp.c	12 Aug 2024 11:25:27 -0000	1.84
+++ sys/netinet/igmp.c	16 Aug 2024 13:11:21 -0000
@@ -687,8 +687,6 @@ igmp_sysctl(int *name, u_int namelen, vo
 
 	switch (name[0]) {
 	case IGMPCTL_STATS:
-		if (newp != NULL)
-			return (EPERM);
 		return (igmp_sysctl_igmpstat(oldp, oldlenp, newp));
 	default:
 		return (EOPNOTSUPP);
Index: sys/netinet/in_proto.c
===================================================================
RCS file: /cvs/src/sys/netinet/in_proto.c,v
diff -u -p -r1.108 in_proto.c
--- sys/netinet/in_proto.c	16 Aug 2024 09:20:35 -0000	1.108
+++ sys/netinet/in_proto.c	16 Aug 2024 13:11:21 -0000
@@ -270,7 +270,7 @@ const struct protosw inetsw[] = {
   .pr_type	= SOCK_RAW,
   .pr_domain	= &inetdomain,
   .pr_protocol	= IPPROTO_IGMP,
-  .pr_flags	= PR_ATOMIC|PR_ADDR|PR_MPSOCKET,
+  .pr_flags	= PR_ATOMIC|PR_ADDR|PR_MPSOCKET|PR_MPSYSCTL,
   .pr_input	= igmp_input,
   .pr_ctloutput	= rip_ctloutput,
   .pr_usrreqs	= &rip_usrreqs,
@@ -342,7 +342,7 @@ const struct protosw inetsw[] = {
   .pr_type	= SOCK_RAW,
   .pr_domain	= &inetdomain,
   .pr_protocol	= IPPROTO_PFSYNC,
-  .pr_flags	= PR_ATOMIC|PR_ADDR|PR_MPSOCKET,
+  .pr_flags	= PR_ATOMIC|PR_ADDR|PR_MPSOCKET|PR_MPSYSCTL,
   .pr_input	= pfsync_input4,
   .pr_ctloutput	= rip_ctloutput,
   .pr_usrreqs	= &rip_usrreqs,
Index: sys/netinet6/in6_proto.c
===================================================================
RCS file: /cvs/src/sys/netinet6/in6_proto.c,v
diff -u -p -r1.118 in6_proto.c
--- sys/netinet6/in6_proto.c	16 Aug 2024 09:20:35 -0000	1.118
+++ sys/netinet6/in6_proto.c	16 Aug 2024 13:11:21 -0000
@@ -158,7 +158,7 @@ const struct protosw inet6sw[] = {
   .pr_type	= SOCK_RAW,
   .pr_domain	= &inet6domain,
   .pr_protocol	= IPPROTO_RAW,
-  .pr_flags	= PR_ATOMIC|PR_ADDR|PR_MPINPUT|PR_MPSOCKET,
+  .pr_flags	= PR_ATOMIC|PR_ADDR|PR_MPINPUT|PR_MPSOCKET|PR_MPSYSCTL,
   .pr_input	= rip6_input,
   .pr_ctlinput	= rip6_ctlinput,
   .pr_ctloutput	= rip6_ctloutput,