[src/trunk]: src/sys/dev/pci On NetBSD it's spelled "__NO_STRICT_ALIGNMENT". ...

[thorpej <thorpej%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/6d15669eea8c
branches:  trunk
changeset: 1008084:6d15669eea8c
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Tue Mar 10 01:23:42 2020 +0000

description:
On NetBSD it's spelled "__NO_STRICT_ALIGNMENT".  Adjust txp_rx_reclaim()
accordingly and structure it like other NetBSD drivers so as to re-use
the original Rx buffer rather than doing a needless free/alloc cycle.

Note this happened to work previously on my Qube2 because IP, TCP, etc.
perform their own alignment checks and react accordingly.  However, it's
not clear that ALL protocols do this yet, so it's better to just do the
safe thing for now.

diffstat:

 sys/dev/pci/if_txp.c |  94 +++++++++++++++++++++++++++------------------------
 1 files changed, 49 insertions(+), 45 deletions(-)

diffs (137 lines):

diff -r c9b60b373d2a -r 6d15669eea8c sys/dev/pci/if_txp.c
--- a/sys/dev/pci/if_txp.c      Tue Mar 10 01:17:33 2020 +0000
+++ b/sys/dev/pci/if_txp.c      Tue Mar 10 01:23:42 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: if_txp.c,v 1.72 2020/03/10 00:26:47 thorpej Exp $ */
+/* $NetBSD: if_txp.c,v 1.73 2020/03/10 01:23:42 thorpej Exp $ */
 
 /*
  * Copyright (c) 2001
@@ -32,7 +32,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_txp.c,v 1.72 2020/03/10 00:26:47 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_txp.c,v 1.73 2020/03/10 01:23:42 thorpej Exp $");
 
 #include "opt_inet.h"
 
@@ -714,6 +714,7 @@
        struct mbuf *m;
        struct txp_swdesc *sd;
        uint32_t roff, woff;
+       uint16_t len;
        int sumflags = 0;
        int idx;
 
@@ -741,44 +742,43 @@
 
                bus_dmamap_sync(sc->sc_dmat, sd->sd_map, 0,
                    sd->sd_map->dm_mapsize, BUS_DMASYNC_POSTREAD);
+
+               len = le16toh(rxd->rx_len);
+
+#ifdef __NO_STRICT_ALIGNMENT
                bus_dmamap_unload(sc->sc_dmat, sd->sd_map);
                m = sd->sd_mbuf;
                sd->sd_mbuf = NULL;
                txp_rxd_free(sc, sd);
-               m->m_pkthdr.len = m->m_len = le16toh(rxd->rx_len);
-
-#ifdef __STRICT_ALIGNMENT
-               {
-                       /*
-                        * XXX Nice chip, except it won't accept "off by 2"
-                        * buffers, so we're force to copy.  Supposedly
-                        * this will be fixed in a newer firmware rev
-                        * and this will be temporary.
-                        */
-                       struct mbuf *mnew;
-
-                       MGETHDR(mnew, M_DONTWAIT, MT_DATA);
-                       if (mnew == NULL) {
+#else
+               /*
+                * The Typhoon's receive buffers must be 4-byte aligned.
+                * But this means the data after the Ethernet header
+                * is misaligned.  We must allocate a new buffer and
+                * copy the data, shifted forward 2 bytes.
+                */
+               MGETHDR(m, M_DONTWAIT, MT_DATA);
+               if (m == NULL) {
+ dropit:
+                       if_statinc(ifp, if_ierrors);
+                       txp_rxd_free(sc, sd);
+                       goto next;
+               }
+               MCLAIM(m, &sc->sc_arpcom.ec_rx_mowner);
+               if (len > (MHLEN - ETHER_ALIGN)) {
+                       MCLGET(m, M_DONTWAIT);
+                       if ((m->m_flags & M_EXT) == 0) {
                                m_freem(m);
-                               goto next;
+                               goto dropit;
                        }
-                       MCLAIM(mnew, &sc->sc_arpcom.ec_rx_mowner);
-                       if (m->m_len > (MHLEN - 2)) {
-                               MCLGET(mnew, M_DONTWAIT);
-                               if (!(mnew->m_flags & M_EXT)) {
-                                       m_freem(mnew);
-                                       m_freem(m);
-                                       goto next;
-                               }
-                       }
-                       m_set_rcvif(mnew, ifp);
-                       mnew->m_pkthdr.len = mnew->m_len = m->m_len;
-                       mnew->m_data += 2;
-                       memcpy(mnew->m_data, m->m_data, m->m_len);
-                       m_freem(m);
-                       m = mnew;
                }
-#endif
+               m_set_rcvif(m, ifp);
+               m->m_data += ETHER_ALIGN;
+               memcpy(mtod(m, void *), mtod(sd->sd_mbuf, void *), len);
+               txp_rxd_free(sc, sd);
+#endif /* __NO_STRICT_ALIGNMENT */
+
+               m->m_pkthdr.len = m->m_len = len;
 
                if (rxd->rx_stat & htole32(RX_STAT_IPCKSUMBAD))
                        sumflags |= (M_CSUM_IPv4 | M_CSUM_IPv4_BAD);
@@ -845,19 +845,23 @@
                if (sd == NULL)
                        break;
 
-               MGETHDR(sd->sd_mbuf, M_DONTWAIT, MT_DATA);
-               if (sd->sd_mbuf == NULL)
-                       goto err_sd;
-               MCLAIM(sd->sd_mbuf, &sc->sc_arpcom.ec_rx_mowner);
+               /* We might already have a buffer allocated. */
+               if (sd->sd_mbuf == NULL) {
+                       MGETHDR(sd->sd_mbuf, M_DONTWAIT, MT_DATA);
+                       if (sd->sd_mbuf == NULL)
+                               goto err_sd;
+                       MCLAIM(sd->sd_mbuf, &sc->sc_arpcom.ec_rx_mowner);
 
-               MCLGET(sd->sd_mbuf, M_DONTWAIT);
-               if ((sd->sd_mbuf->m_flags & M_EXT) == 0)
-                       goto err_mbuf;
-               m_set_rcvif(sd->sd_mbuf, ifp);
-               sd->sd_mbuf->m_pkthdr.len = sd->sd_mbuf->m_len = MCLBYTES;
-               if (bus_dmamap_load_mbuf(sc->sc_dmat, sd->sd_map, sd->sd_mbuf,
-                   BUS_DMA_NOWAIT)) {
-                       goto err_mbuf;
+                       MCLGET(sd->sd_mbuf, M_DONTWAIT);
+                       if ((sd->sd_mbuf->m_flags & M_EXT) == 0)
+                               goto err_mbuf;
+                       m_set_rcvif(sd->sd_mbuf, ifp);
+                       sd->sd_mbuf->m_pkthdr.len =
+                           sd->sd_mbuf->m_len = MCLBYTES;
+                       if (bus_dmamap_load_mbuf(sc->sc_dmat, sd->sd_map,
+                           sd->sd_mbuf, BUS_DMA_NOWAIT)) {
+                               goto err_mbuf;
+                       }
                }
 
                bus_dmamap_sync(sc->sc_dmat, sc->sc_rxbufring_dma.dma_map,