When processing a received packet, only sync the amount of bytes

mcx(4) told us has arrived.  The DMA map's mapsize on RX packets
is the length of the allocated buffer.  For mcx(4), this can be
more than around 9000 bytes, as each buffer will be at least as
big as the maximum supported MTU.  There's no need to sync the
whole buffer, if it's only a small packet.

ok dlg@ jmatthew@

diff --git a/sys/dev/pci/if_mcx.c b/sys/dev/pci/if_mcx.c
index 38437e5..99b7c5f 100644 (file)
--- a/sys/dev/pci/if_mcx.c
+++ b/sys/dev/pci/if_mcx.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: if_mcx.c,v 1.100 2021/02/25 02:48:20 dlg Exp $ */
+/*     $OpenBSD: if_mcx.c,v 1.101 2021/06/02 19:16:11 patrick Exp $ */
 
 /*
  * Copyright (c) 2017 David Gwynne <dlg@openbsd.org>
@@ -6800,20 +6800,20 @@ mcx_process_rx(struct mcx_softc *sc, struct mcx_rx *rx,
 {
        struct mcx_slot *ms;
        struct mbuf *m;
-       uint32_t flags;
+       uint32_t flags, len;
        int slot;
 
+       len = bemtoh32(&cqe->cq_byte_cnt);
        slot = betoh16(cqe->cq_wqe_count) % (1 << MCX_LOG_RQ_SIZE);
 
        ms = &rx->rx_slots[slot];
-       bus_dmamap_sync(sc->sc_dmat, ms->ms_map, 0, ms->ms_map->dm_mapsize,
-           BUS_DMASYNC_POSTREAD);
+       bus_dmamap_sync(sc->sc_dmat, ms->ms_map, 0, len, BUS_DMASYNC_POSTREAD);
        bus_dmamap_unload(sc->sc_dmat, ms->ms_map);
 
        m = ms->ms_m;
        ms->ms_m = NULL;
 
-       m->m_pkthdr.len = m->m_len = bemtoh32(&cqe->cq_byte_cnt);
+       m->m_pkthdr.len = m->m_len = len;
 
        if (cqe->cq_rx_hash_type) {
                m->m_pkthdr.ph_flowid = betoh32(cqe->cq_rx_hash);