SEO

txp(4) is calling m_prepend() directly instead of using the better
M_PREPEND() makro. The following diff changes this, additionally it moves
the vlan handling above the strict aligenment block and add some head
space in the mbufs. These two additional changes are optimizations so that
no additional mbuf is prepended when the vlan header is inserted.

As I do not have the HW I need somebody to test this with and without
vlans. Thanks in advance.
--
:wq Claudio

Index: if_txp.c
================================================== =================
RCS file: /cvs/src/sys/dev/pci/if_txp.c,v
retrieving revision 1.83
diff -u -p -r1.83 if_txp.c
--- if_txp.c 29 Jun 2006 21:36:40 -0000 1.83
+++ if_txp.c 15 Mar 2007 12:07:37 -0000
@@ -657,6 +657,31 @@ txp_rx_reclaim(sc, r, dma)
free(sd, M_DEVBUF);
m->m_pkthdr.len = m->m_len = letoh16(rxd->rx_len);

+#if NVLAN > 0
+ /*
+ * XXX Another firmware bug: the vlan encapsulation
+ * is always removed, even when we tell the card not
+ * to do that. Restore the vlan encapsulation below.
+ */
+ if (rxd->rx_stat & htole32(RX_STAT_VLAN)) {
+ struct ether_vlan_header vh;
+
+ if (m->m_pkthdr.len < ETHER_HDR_LEN) {
+ m_freem(m);
+ goto next;
+ }
+ m_copydata(m, 0, ETHER_HDR_LEN, (caddr_t)&vh);
+ vh.evl_proto = vh.evl_encap_proto;
+ vh.evl_tag = rxd->rx_vlan >> 16;
+ vh.evl_encap_proto = htons(ETHERTYPE_VLAN);
+ m_adj(m, ETHER_HDR_LEN);
+ M_PREPEND(m, sizeof(vh), M_DONTWAIT);
+ if (m == NULL)
+ goto next;
+ m_copyback(m, 0, sizeof(vh), &vh);
+ }
+#endif
+
#ifdef __STRICT_ALIGNMENT
{
/*
@@ -689,34 +714,6 @@ txp_rx_reclaim(sc, r, dma)
}
#endif

-#if NVLAN > 0
- /*
- * XXX Another firmware bug: the vlan encapsulation
- * is always removed, even when we tell the card not
- * to do that. Restore the vlan encapsulation below.
- */
- if (rxd->rx_stat & htole32(RX_STAT_VLAN)) {
- struct ether_vlan_header vh;
-
- if (m->m_pkthdr.len < ETHER_HDR_LEN) {
- m_freem(m);
- goto next;
- }
- m_copydata(m, 0, ETHER_HDR_LEN, (caddr_t)&vh);
- vh.evl_proto = vh.evl_encap_proto;
- vh.evl_tag = rxd->rx_vlan >> 16;
- vh.evl_encap_proto = htons(ETHERTYPE_VLAN);
- m_adj(m, ETHER_HDR_LEN);
- if ((m = m_prepend(m, sizeof(vh), M_DONTWAIT)) == NULL)
- goto next;
- m->m_pkthdr.len += sizeof(vh);
- if (m->m_len < sizeof(vh) &&
- (m = m_pullup(m, sizeof(vh))) == NULL)
- goto next;
- m_copyback(m, 0, sizeof(vh), &vh);
- }
-#endif
-
#if NBPFILTER > 0
/*
* Handle BPF listeners. Let the BPF user see the packet.
@@ -795,8 +792,10 @@ txp_rxbuf_reclaim(sc)
MCLGET(sd->sd_mbuf, M_DONTWAIT);
if ((sd->sd_mbuf->m_flags & M_EXT) == 0)
goto err_mbuf;
+ /* reserve some space for a possible VLAN header */
+ sd->sd_mbuf->m_data += 8;
+ sd->sd_mbuf->m_pkthdr.len = sd->sd_mbuf->m_len = MCLBYTES - 8;
sd->sd_mbuf->m_pkthdr.rcvif = ifp;
- sd->sd_mbuf->m_pkthdr.len = sd->sd_mbuf->m_len = MCLBYTES;
if (bus_dmamap_create(sc->sc_dmat, TXP_MAX_PKTLEN, 1,
TXP_MAX_PKTLEN, 0, BUS_DMA_NOWAIT, &sd->sd_map))
goto err_mbuf;
@@ -1081,7 +1080,9 @@ txp_alloc_rings(sc)
if ((sd->sd_mbuf->m_flags & M_EXT) == 0) {
goto bail_rxbufring;
}
- sd->sd_mbuf->m_pkthdr.len = sd->sd_mbuf->m_len = MCLBYTES;
+ /* reserve some space for a possible VLAN header */
+ sd->sd_mbuf->m_data += 8;
+ sd->sd_mbuf->m_pkthdr.len = sd->sd_mbuf->m_len = MCLBYTES - 8;
sd->sd_mbuf->m_pkthdr.rcvif = ifp;
if (bus_dmamap_create(sc->sc_dmat, TXP_MAX_PKTLEN, 1,
TXP_MAX_PKTLEN, 0, BUS_DMA_NOWAIT, &sd->sd_map)) {