[src/trunk]: src/sys/dev/pci age_encap(): Use m_defrag(), not m_pullup(), to ...

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

details:   https://anonhg.NetBSD.org/src/rev/44b41b32d0f7
branches:  trunk
changeset: 369591:44b41b32d0f7
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Mon Aug 22 16:14:31 2022 +0000

description:
age_encap(): Use m_defrag(), not m_pullup(), to compact an mbuf chain
if it has too many DMA segments.  Let the caller handle dispose of the
packet on fatal errors.

diffstat:

 sys/dev/pci/if_age.c |  64 ++++++++++++++++++++++-----------------------------
 1 files changed, 28 insertions(+), 36 deletions(-)

diffs (136 lines):

diff -r 492a57109f43 -r 44b41b32d0f7 sys/dev/pci/if_age.c
--- a/sys/dev/pci/if_age.c      Mon Aug 22 15:59:42 2022 +0000
+++ b/sys/dev/pci/if_age.c      Mon Aug 22 16:14:31 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_age.c,v 1.70 2022/05/31 08:43:15 andvar Exp $ */
+/*     $NetBSD: if_age.c,v 1.71 2022/08/22 16:14:31 thorpej Exp $ */
 /*     $OpenBSD: if_age.c,v 1.1 2009/01/16 05:00:34 kevlo Exp $        */
 
 /*-
@@ -31,7 +31,7 @@
 /* Driver for Attansic Technology Corp. L1 Gigabit Ethernet. */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_age.c,v 1.70 2022/05/31 08:43:15 andvar Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_age.c,v 1.71 2022/08/22 16:14:31 thorpej Exp $");
 
 #include "vlan.h"
 
@@ -98,7 +98,7 @@
 static void    age_get_macaddr(struct age_softc *, uint8_t[]);
 static void    age_phy_reset(struct age_softc *);
 
-static int     age_encap(struct age_softc *, struct mbuf **);
+static int     age_encap(struct age_softc *, struct mbuf *);
 static void    age_init_tx_ring(struct age_softc *);
 static int     age_init_rx_ring(struct age_softc *);
 static void    age_init_rr_ring(struct age_softc *);
@@ -1056,7 +1056,7 @@
 {
        struct age_softc *sc = ifp->if_softc;
        struct mbuf *m_head;
-       int enq;
+       int enq, error;
 
        if ((ifp->if_flags & (IFF_RUNNING | IFF_OACTIVE)) != IFF_RUNNING)
                return;
@@ -1076,9 +1076,13 @@
                 * don't have room, set the OACTIVE flag and wait
                 * for the NIC to drain the ring.
                 */
-               if (age_encap(sc, &m_head)) {
-                       if (m_head == NULL)
-                               break;
+               if ((error = age_encap(sc, m_head)) != 0) {
+                       if (error == EFBIG) {
+                               /* This is fatal for the packet. */
+                               m_freem(m_head);
+                               if_statinc(ifp, if_oerrors);
+                               continue;
+                       }
                        IF_PREPEND(&ifp->if_snd, m_head);
                        ifp->if_flags |= IFF_OACTIVE;
                        break;
@@ -1213,16 +1217,14 @@
 }
 
 static int
-age_encap(struct age_softc *sc, struct mbuf **m_head)
+age_encap(struct age_softc *sc, struct mbuf * const m)
 {
        struct age_txdesc *txd, *txd_last;
        struct tx_desc *desc;
-       struct mbuf *m;
        bus_dmamap_t map;
        uint32_t cflags, poff, vtag;
        int error, i, nsegs, prod;
 
-       m = *m_head;
        cflags = vtag = 0;
        poff = 0;
 
@@ -1231,40 +1233,31 @@
        txd_last = txd;
        map = txd->tx_dmamap;
 
-       error = bus_dmamap_load_mbuf(sc->sc_dmat, map, *m_head, BUS_DMA_NOWAIT);
-
+       error = bus_dmamap_load_mbuf(sc->sc_dmat, map, m, BUS_DMA_NOWAIT);
        if (error == EFBIG) {
-               error = 0;
-
-               *m_head = m_pullup(*m_head, MHLEN);
-               if (*m_head == NULL) {
-                       printf("%s: can't defrag TX mbuf\n",
-                           device_xname(sc->sc_dev));
-                       return ENOBUFS;
+               struct mbuf *mnew = m_defrag(m, M_NOWAIT);
+               if (mnew != NULL) {
+                       KASSERT(m == mnew);
+                       error = bus_dmamap_load_mbuf(sc->sc_dmat, map, mnew,
+                           BUS_DMA_NOWAIT);
+               } else {
+                       /* Just drop if we can't defrag. */
+                       error = EFBIG;
                }
-
-               error = bus_dmamap_load_mbuf(sc->sc_dmat, map, *m_head,
-                           BUS_DMA_NOWAIT);
-
-               if (error != 0) {
-                       printf("%s: could not load defragged TX mbuf\n",
-                           device_xname(sc->sc_dev));
-                       m_freem(*m_head);
-                       *m_head = NULL;
+               if (error) {
+                       if (error == EFBIG) {
+                               printf("%s: Tx packet consumes too many "
+                                   "DMA segments, dropping...\n",
+                                   device_xname(sc->sc_dev));
+                       }
                        return error;
                }
        } else if (error) {
-               printf("%s: could not load TX mbuf\n", device_xname(sc->sc_dev));
                return error;
        }
 
        nsegs = map->dm_nsegs;
-
-       if (nsegs == 0) {
-               m_freem(*m_head);
-               *m_head = NULL;
-               return EIO;
-       }
+       KASSERT(nsegs != 0);
 
        /* Check descriptor overrun. */
        if (sc->age_cdata.age_tx_cnt + nsegs >= AGE_TX_RING_CNT - 2) {
@@ -1274,7 +1267,6 @@
        bus_dmamap_sync(sc->sc_dmat, map, 0, map->dm_mapsize,
            BUS_DMASYNC_PREWRITE);
 
-       m = *m_head;
        /* Configure Tx IP/TCP/UDP checksum offload. */
        if ((m->m_pkthdr.csum_flags & AGE_CSUM_FEATURES) != 0) {
                cflags |= AGE_TD_CSUM;