The in6_setscope() function determines the scope zone id of an address

and embeds it into address. Inside the kernel we keep addresses with
embedded zone id only for two scopes: link-local and interface-local.

For other scopes this function is nop in most cases. To reduce an
overhead of locking, first check that address is capable for embedding.
Also, handle the loopback address before acquire the lock.

Sponsored by:	Yandex LLC
MFC after:	1 week

1 files changed, 15 insertions, 14 deletions

diff --git a/sys/netinet6/scope6.c b/sys/netinet6/scope6.c
index 060fe59..74d034e 100644
--- a/sys/netinet6/scope6.c
+++ b/sys/netinet6/scope6.c
@@ -420,33 +420,34 @@ in6_setscope(struct in6_addr *in6, struct ifnet *ifp, u_int32_t *ret_id)
 	u_int32_t zoneid = 0;
 	struct scope6_id *sid;
 
-	IF_AFDATA_RLOCK(ifp);
-
-	sid = SID(ifp);
-
-#ifdef DIAGNOSTIC
-	if (sid == NULL) { /* should not happen */
-		panic("in6_setscope: scope array is NULL");
-		/* NOTREACHED */
-	}
-#endif
-
 	/*
 	 * special case: the loopback address can only belong to a loopback
 	 * interface.
 	 */
 	if (IN6_IS_ADDR_LOOPBACK(in6)) {
 		if (!(ifp->if_flags & IFF_LOOPBACK)) {
-			IF_AFDATA_RUNLOCK(ifp);
 			return (EINVAL);
 		} else {
 			if (ret_id != NULL)
 				*ret_id = 0; /* there's no ambiguity */
-			IF_AFDATA_RUNLOCK(ifp);
 			return (0);
 		}
 	}
 
+	if (ret_id == NULL && !IN6_IS_SCOPE_EMBED(in6))
+		return (0);
+
+	IF_AFDATA_RLOCK(ifp);
+
+	sid = SID(ifp);
+
+#ifdef DIAGNOSTIC
+	if (sid == NULL) { /* should not happen */
+		panic("in6_setscope: scope array is NULL");
+		/* NOTREACHED */
+	}
+#endif
+
 	scope = in6_addrscope(in6);
 	switch (scope) {
 	case IPV6_ADDR_SCOPE_INTFACELOCAL: /* should be interface index */
@@ -474,7 +475,7 @@ in6_setscope(struct in6_addr *in6, struct ifnet *ifp, u_int32_t *ret_id)
 	if (ret_id != NULL)
 		*ret_id = zoneid;
 
-	if (IN6_IS_SCOPE_LINKLOCAL(in6) || IN6_IS_ADDR_MC_INTFACELOCAL(in6))
+	if (IN6_IS_SCOPE_EMBED(in6))
 		in6->s6_addr16[1] = htons(zoneid & 0xffff); /* XXX */
 
 	return (0);