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

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

details:   https://anonhg.NetBSD.org/src/rev/12d3acd36218
branches:  trunk
changeset: 369588:12d3acd36218
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Mon Aug 22 15:39:26 2022 +0000

description:
ale_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_ale.c |  60 ++++++++++++++++++++-------------------------------
 1 files changed, 24 insertions(+), 36 deletions(-)

diffs (131 lines):

diff -r 1df271e85748 -r 12d3acd36218 sys/dev/pci/if_ale.c
--- a/sys/dev/pci/if_ale.c      Mon Aug 22 13:57:24 2022 +0000
+++ b/sys/dev/pci/if_ale.c      Mon Aug 22 15:39:26 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_ale.c,v 1.40 2020/03/01 02:28:14 thorpej Exp $      */
+/*     $NetBSD: if_ale.c,v 1.41 2022/08/22 15:39:26 thorpej Exp $      */
 
 /*-
  * Copyright (c) 2008, Pyun YongHyeon <yongari%FreeBSD.org@localhost>
@@ -32,7 +32,7 @@
 /* Driver for Atheros AR8121/AR8113/AR8114 PCIe Ethernet. */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_ale.c,v 1.40 2020/03/01 02:28:14 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_ale.c,v 1.41 2022/08/22 15:39:26 thorpej Exp $");
 
 #include "vlan.h"
 
@@ -102,7 +102,7 @@
 
 static int     ale_dma_alloc(struct ale_softc *);
 static void    ale_dma_free(struct ale_softc *);
-static int     ale_encap(struct ale_softc *, struct mbuf **);
+static int     ale_encap(struct ale_softc *, struct mbuf *);
 static void    ale_init_rx_pages(struct ale_softc *);
 static void    ale_init_tx_ring(struct ale_softc *);
 
@@ -908,16 +908,14 @@
 }
 
 static int
-ale_encap(struct ale_softc *sc, struct mbuf **m_head)
+ale_encap(struct ale_softc *sc, struct mbuf * const m)
 {
        struct ale_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;
 
@@ -926,39 +924,26 @@
        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);
                }
-
-               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",
+               if (mnew == NULL || error == EFBIG) {
+                       printf("%s: Tx packet consumes too many "
+                           "DMA segments, dropping...\n",
                            device_xname(sc->sc_dev));
-                       m_freem(*m_head);
-                       *m_head = NULL;
-                       return error;
+                       return EFBIG;
                }
-       } else if (error) {
-               printf("%s: could not load TX mbuf\n", device_xname(sc->sc_dev));
+       } else if (error != 0) {
                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->ale_cdata.ale_tx_cnt + nsegs >= ALE_TX_RING_CNT - 2) {
@@ -968,7 +953,6 @@
        bus_dmamap_sync(sc->sc_dmat, map, 0, map->dm_mapsize,
            BUS_DMASYNC_PREWRITE);
 
-       m = *m_head;
        /* Configure Tx checksum offload. */
        if ((m->m_pkthdr.csum_flags & ALE_CSUM_FEATURES) != 0) {
                /*
@@ -1044,7 +1028,7 @@
 {
        struct ale_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;
@@ -1064,9 +1048,13 @@
                 * don't have room, set the OACTIVE flag and wait
                 * for the NIC to drain the ring.
                 */
-               if (ale_encap(sc, &m_head)) {
-                       if (m_head == NULL)
-                               break;
+               if ((error = ale_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;