ipv6: Remove setsockopt_needs_rtnl().

JIRA: https://issues.redhat.com/browse/RHEL-115325

commit db38443
Author: Kuniyuki Iwashima <kuniyu@google.com>
Date:   Wed Jul 2 16:01:32 2025 -0700

    ipv6: Remove setsockopt_needs_rtnl().

    We no longer need to hold RTNL for IPv6 socket options.

    Let's remove setsockopt_needs_rtnl().

    Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
    Reviewed-by: Eric Dumazet <edumazet@google.com>
    Link: https://patch.msgid.link/20250702230210.3115355-16-kuni1840@gmail.com
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: CKI Backport Bot <cki-ci-bot+cki-gitlab-backport-bot@redhat.com>

Author: CKI Backport Bot

net/ipv6/ipv6_sockglue.c

@@ -117,11 +117,6 @@ struct ipv6_txoptions *ipv6_update_options(struct sock *sk,
 	return opt;
 }
 
-static bool setsockopt_needs_rtnl(int optname)
-{
-	return false;
-}
-
 static int copy_group_source_from_sockptr(struct group_source_req *greqs,
 		sockptr_t optval, int optlen)
 {
@@ -380,9 +375,8 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 {
 	struct ipv6_pinfo *np = inet6_sk(sk);
 	struct net *net = sock_net(sk);
-	int val, valbool;
 	int retv = -ENOPROTOOPT;
-	bool needs_rtnl = setsockopt_needs_rtnl(optname);
+	int val, valbool;
 
 	if (sockptr_is_null(optval))
 		val = 0;
@@ -547,8 +541,7 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 		return 0;
 	}
 	}
-	if (needs_rtnl)
-		rtnl_lock();
+
 	sockopt_lock_sock(sk);
 
 	/* Another thread has converted the socket into IPv4 with
@@ -954,8 +947,6 @@ int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 
 unlock:
 	sockopt_release_sock(sk);
-	if (needs_rtnl)
-		rtnl_unlock();
 
 	return retv;