[src/trunk]: src/sys/dev/ic Avoid "hole in RX ring" condition by ensuring a n...

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

details:   https://anonhg.NetBSD.org/src/rev/5058191decb6
branches:  trunk
changeset: 746353:5058191decb6
user:      jmcneill <jmcneill%NetBSD.org@localhost>
date:      Sun Mar 29 13:04:15 2020 +0000

description:
Avoid "hole in RX ring" condition by ensuring a new mbuf is available
before using an existing one.

diffstat:

 sys/dev/ic/bcmgenet.c |  28 ++++++++++++++--------------
 1 files changed, 14 insertions(+), 14 deletions(-)

diffs (63 lines):

diff -r 641f8af4e0f2 -r 5058191decb6 sys/dev/ic/bcmgenet.c
--- a/sys/dev/ic/bcmgenet.c     Sun Mar 29 10:46:10 2020 +0000
+++ b/sys/dev/ic/bcmgenet.c     Sun Mar 29 13:04:15 2020 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: bcmgenet.c,v 1.3 2020/02/27 17:30:07 jmcneill Exp $ */
+/* $NetBSD: bcmgenet.c,v 1.4 2020/03/29 13:04:15 jmcneill Exp $ */
 
 /*-
  * Copyright (c) 2020 Jared McNeill <jmcneill%invisible.ca@localhost>
@@ -34,7 +34,7 @@
 #include "opt_ddb.h"
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: bcmgenet.c,v 1.3 2020/02/27 17:30:07 jmcneill Exp $");
+__KERNEL_RCSID(0, "$NetBSD: bcmgenet.c,v 1.4 2020/03/29 13:04:15 jmcneill Exp $");
 
 #include <sys/param.h>
 #include <sys/bus.h>
@@ -626,7 +626,17 @@
                status = RD4(sc, GENET_RX_DESC_STATUS(index));
                len = __SHIFTOUT(status, GENET_RX_DESC_STATUS_BUFLEN);
 
-               /* XXX check for errors */
+               m = sc->sc_rx.buf_map[index].mbuf;
+
+               if ((m0 = genet_alloc_mbufcl(sc)) == NULL) {
+                       if_statinc(ifp, if_ierrors);
+                       goto next;
+               }
+               error = genet_setup_rxbuf(sc, index, m0);
+               if (error != 0) {
+                       if_statinc(ifp, if_ierrors);
+                       goto next;
+               }
 
                bus_dmamap_sync(sc->sc_rx.buf_tag, sc->sc_rx.buf_map[index].map,
                    0, sc->sc_rx.buf_map[index].map->dm_mapsize,
@@ -637,8 +647,6 @@
                    n, index, status, len, len - ETHER_ALIGN);
 
                if (len > ETHER_ALIGN) {
-                       m = sc->sc_rx.buf_map[index].mbuf;
-
                        m_adj(m, ETHER_ALIGN);
 
                        m_set_rcvif(m, ifp);
@@ -648,15 +656,7 @@
                        if_percpuq_enqueue(ifp->if_percpuq, m);
                }
 
-               if ((m0 = genet_alloc_mbufcl(sc)) != NULL) {
-                       error = genet_setup_rxbuf(sc, index, m0);
-                       if (error != 0) {
-                               /* XXX hole in RX ring */
-                       }
-               } else {
-                       if_statinc(ifp, if_ierrors);
-               }
-
+next:
                index = RX_NEXT(index);
 
                sc->sc_rx.cidx = (sc->sc_rx.cidx + 1) & 0xffff;