we used to handle the vlan tag etc insertion very very very late,

on al already ass embed ethernet frame, which meant:
-copy (most of) the existing ethernet header into a ether_vlan_header
on the stack
-fill the extra fields in ether_vlan_header
-set the ether type
-m_adj() to make room for the extra space ether_vlan_header needs
-m_copyback the ether_vlan_header into the mbuf
that involves moving data around, which isn't all that cheap.
cleaner & easier to have ether_output prepend the ether_vlan_header instead
of the regular ethernet header, which makes the vlan tagging essentially
free in most cases.
help & ok reyk, naddy; waste of time bikeshedding tech@

2 files changed, 51 insertions, 36 deletions

diff --git a/sys/net/if_ethersubr.c b/sys/net/if_ethersubr.c
index 09fb772a4fa..1a473cc6571 100644
--- a/sys/net/if_ethersubr.c
+++ b/sys/net/if_ethersubr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_ethersubr.c,v 1.170 2014/04/21 18:52:25 henning Exp $	*/
+/*	$OpenBSD: if_ethersubr.c,v 1.171 2014/04/22 11:43:07 henning Exp $	*/
 /*	$NetBSD: if_ethersubr.c,v 1.19 1996/05/07 02:40:30 thorpej Exp $	*/
 
 /*
@@ -155,8 +155,8 @@ u_char etherbroadcastaddr[ETHER_ADDR_LEN] =
     { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 #define senderr(e) { error = (e); goto bad;}
 
-static inline int    ether_addheader(struct mbuf **, u_int16_t, u_char *,
-			   u_char *);
+static inline int	ether_addheader(struct mbuf **, struct ifnet *,
+			   u_int16_t, u_char *, u_char *);
 
 int
 ether_ioctl(struct ifnet *ifp, struct arpcom *arp, u_long cmd, caddr_t data)
@@ -193,10 +193,40 @@ ether_ioctl(struct ifnet *ifp, struct arpcom *arp, u_long cmd, caddr_t data)
 }
 
 static inline int
-ether_addheader(struct mbuf **m, u_int16_t etype, u_char *esrc, u_char *edst)
+ether_addheader(struct mbuf **m, struct ifnet *ifp, u_int16_t etype,
+    u_char *esrc, u_char *edst)
 {
 	struct ether_header *eh;
 
+#if NVLAN > 0
+	if ((*m)->m_flags & M_VLANTAG) {
+		struct ifvlan	*ifv = ifp->if_softc;
+		struct ifnet	*p = ifv->ifv_p;
+
+		/* should we use the tx tagging hw offload at all? */
+		if ((p->if_capabilities & IFCAP_VLAN_HWTAGGING) &&
+		    (ifv->ifv_type == ETHERTYPE_VLAN)) {
+			(*m)->m_pkthdr.ether_vtag = ifv->ifv_tag +
+			    ((*m)->m_pkthdr.pf.prio << EVL_PRIO_BITS);
+			/* don't return, need to add regular ethernet header */
+		} else {
+			struct ether_vlan_header	*evh;
+
+			M_PREPEND(*m, sizeof(*evh), M_DONTWAIT);
+			if (*m == 0)
+				return (-1);
+			evh = mtod(*m, struct ether_vlan_header *);
+			memcpy(evh->evl_dhost, edst, sizeof(evh->evl_dhost));
+			memcpy(evh->evl_shost, esrc, sizeof(evh->evl_shost));
+			evh->evl_proto = etype;
+			evh->evl_encap_proto = htons(ifv->ifv_type);
+			evh->evl_tag = htons(ifv->ifv_tag +
+			    ((*m)->m_pkthdr.pf.prio << EVL_PRIO_BITS));
+			(*m)->m_flags &= ~M_VLANTAG;
+			return (0);
+		}
+	}
+#endif /* NVLAN > 0 */
 	M_PREPEND(*m, ETHER_HDR_LEN, M_DONTWAIT);
 	if (*m == 0)
 		return (-1);
@@ -364,7 +394,7 @@ ether_output(struct ifnet *ifp0, struct mbuf *m0, struct sockaddr *dst,
 		esrc = carp_get_srclladdr(ifp0, esrc);
 #endif
 
-	if (ether_addheader(&m, etype, esrc, edst) == -1)
+	if (ether_addheader(&m, ifp, etype, esrc, edst) == -1)
 		senderr(ENOBUFS);
 
 #if NBRIDGE > 0
diff --git a/sys/net/if_vlan.c b/sys/net/if_vlan.c
index 274364993b1..2c9bb1284cf 100644
--- a/sys/net/if_vlan.c
+++ b/sys/net/if_vlan.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_vlan.c,v 1.102 2014/03/10 12:21:35 mpi Exp $	*/
+/*	$OpenBSD: if_vlan.c,v 1.103 2014/04/22 11:43:07 henning Exp $	*/
 
 /*
  * Copyright 1998 Massachusetts Institute of Technology
@@ -80,6 +80,8 @@ u_long vlan_tagmask, svlan_tagmask;
 #define TAG_HASH(tag)		(tag & vlan_tagmask)
 LIST_HEAD(vlan_taghash, ifvlan)	*vlan_tagh, *svlan_tagh;
 
+int	vlan_output(struct ifnet *, struct mbuf *, struct sockaddr *,
+	    struct rtentry *);
 void	vlan_start(struct ifnet *ifp);
 int	vlan_ioctl(struct ifnet *ifp, u_long cmd, caddr_t addr);
 int	vlan_unconfig(struct ifnet *ifp, struct ifnet *newp);
@@ -152,6 +154,7 @@ vlan_clone_create(struct if_clone *ifc, int unit)
 	/* Now undo some of the damage... */
 	ifp->if_type = IFT_L2VLAN;
 	ifp->if_hdrlen = EVL_ENCAPLEN;
+	ifp->if_output = vlan_output;
 
 	return (0);
 }
@@ -177,6 +180,18 @@ vlan_ifdetach(void *ptr)
 	vlan_clone_destroy(&ifv->ifv_if);
 }
 
+int
+vlan_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
+    struct rtentry *rt)
+{
+	/*
+	 * we have to use a custom output function because ether_output
+	 * can't figure out ifp is a vlan in a reasonable way
+	 */
+	m->m_flags |= M_VLANTAG;
+	return (ether_output(ifp, m, dst, rt));
+}
+
 void
 vlan_start(struct ifnet *ifp)
 {
@@ -208,36 +223,6 @@ vlan_start(struct ifnet *ifp)
 #endif
 
 		/*
-		 * If the IFCAP_VLAN_HWTAGGING capability is set on the parent,
-		 * it can do VLAN tag insertion itself and doesn't require us
-	 	 * to create a special header for it. In this case, we just pass
-		 * the packet along.
-		 */
-		if ((p->if_capabilities & IFCAP_VLAN_HWTAGGING) &&
-		    (ifv->ifv_type == ETHERTYPE_VLAN)) {
-			m->m_pkthdr.ether_vtag = ifv->ifv_tag +
-			    (m->m_pkthdr.pf.prio << EVL_PRIO_BITS);
-			m->m_flags |= M_VLANTAG;
-		} else {
-			struct ether_vlan_header evh;
-
-			m_copydata(m, 0, ETHER_HDR_LEN, (caddr_t)&evh);
-			evh.evl_proto = evh.evl_encap_proto;
-			evh.evl_encap_proto = htons(ifv->ifv_type);
-			evh.evl_tag = htons(ifv->ifv_tag +
-			    (m->m_pkthdr.pf.prio << EVL_PRIO_BITS));
-
-			m_adj(m, ETHER_HDR_LEN);
-			M_PREPEND(m, sizeof(evh), M_DONTWAIT);
-			if (m == NULL) {
-				ifp->if_oerrors++;
-				continue;
-			}
-
-			m_copyback(m, 0, sizeof(evh), &evh, M_NOWAIT);
-		}
-
-		/*
 		 * Send it, precisely as ether_output() would have.
 		 * We are already running at splnet.
 		 */