Remove GIANT_REQUIRED from IPv6 input, forward, and frag6 code. The frag6

code is believed to be MPSAFE, and leaving aside the IPv6 route cache in
forwarding, Giant appears not to adequately synchronize the data structures
in the input or forwarding paths.

sys/netinet6/frag6.c

@@ -683,10 +683,6 @@ frag6_slowtimo(void)
 {
 	struct ip6q *q6;
 
-#if 0
-	GIANT_REQUIRED;	/* XXX bz: ip6_forward_rt */
-#endif
-
 	IP6Q_LOCK();
 	q6 = ip6q.ip6q_next;
 	if (q6)

sys/netinet6/ip6_forward.c

@@ -106,7 +106,7 @@ ip6_forward(struct mbuf *m, int srcrt)
 #endif
 	char ip6bufs[INET6_ADDRSTRLEN], ip6bufd[INET6_ADDRSTRLEN];
 
-	GIANT_REQUIRED; /* XXX bz: ip6_forward_rt */
+	/* GIANT_REQUIRED; */ /* XXX bz: ip6_forward_rt */
 
 #ifdef IPSEC
 	/*

sys/netinet6/ip6_input.c

@@ -222,8 +222,6 @@ ip6_input(struct mbuf *m)
 	struct in6_addr odst;
 	int srcrt = 0;
 
-	GIANT_REQUIRED;			/* XXX for now */
-
 #ifdef IPSEC
 	/*
 	 * should the inner packet be considered authentic?