Date: Mon, 5 Jan 2004 21:53:21 +0100 From: Maxime Henrion <mux@freebsd.org> To: Don Lewis <truckman@FreeBSD.org> Cc: current@FreeBSD.org Subject: Re: 5.2-RC oerrs and collisions on dc0 Message-ID: <20040105205321.GN2060@elvis.mu.org> In-Reply-To: <200401052007.i05K7K7E012100@gw.catspoiler.org> References: <20040105183445.GK2060@elvis.mu.org> <200401052007.i05K7K7E012100@gw.catspoiler.org>
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Don Lewis wrote:
> On 5 Jan, Maxime Henrion wrote:
> > Don Lewis wrote:
> >> I just took a closer look at the busdma diff, and this change to
> >> dc_txeof() looks very suspicious:
> >>
> >> @@ -2663,7 +2809,7 @@
> >> if (txstat & DC_TXSTAT_OWN)
> >> break;
> >>
> >> - if (!(cur_tx->dc_ctl & DC_TXCTL_LASTFRAG) ||
> >> + if (!(cur_tx->dc_ctl & DC_TXCTL_FIRSTFRAG) ||
> >> cur_tx->dc_ctl & DC_TXCTL_SETUP) {
> >> if (cur_tx->dc_ctl & DC_TXCTL_SETUP) {
> >> /*
> >>
> >> The code in the "if" block ends with a "continue" which will cause the
> >> error handling code to be skipped if the "if" condition is true. I'm
> >> pretty sure that the error status bits are only set in the last
> >> descriptor for the frame, so we want to execute the "continue" unless
> >> the DC_TXCTL_LASTFRAG bit is set.
> >>
> >> Try reverting this part of the busdma change.
> >
> > I think you actually found the culprit, though fixing this is not as
> > simple as reverting this line. I changed the check to
> > DC_TXCTL_FIRSTFRAG because that's the descriptor which will have a link
> > to the mbuf, while it was previously done for the LASTFRAG descriptor.
> > However, I didn't think about the code flow enough it seems. If you
> > don't have a fix for this soon, I should be able to do it pretty easily,
> > assuming I find the time.
>
> How about something like the following. I can't test it because I don't
> have the appropriate hardware, but at least it compiles ;-)
>
> Index: sys/pci/if_dc.c
> ===================================================================
> RCS file: /home/ncvs/src/sys/pci/if_dc.c,v
> retrieving revision 1.137
> diff -u -r1.137 if_dc.c
> --- sys/pci/if_dc.c 6 Dec 2003 02:29:31 -0000 1.137
> +++ sys/pci/if_dc.c 5 Jan 2004 20:00:04 -0000
> @@ -2859,7 +2859,7 @@
> if (txstat & DC_TXSTAT_OWN)
> break;
>
> - if (!(ctl & DC_TXCTL_FIRSTFRAG) || ctl & DC_TXCTL_SETUP) {
> + if (!(ctl & DC_TXCTL_LASTFRAG) || ctl & DC_TXCTL_SETUP) {
> if (ctl & DC_TXCTL_SETUP) {
> /*
> * Yes, the PNIC is so brain damaged
> @@ -3262,6 +3262,7 @@
> sc->dc_cdata.dc_tx_prod = frag;
> sc->dc_cdata.dc_tx_cnt += nseg;
> sc->dc_ldata->dc_tx_list[cur].dc_ctl |= htole32(DC_TXCTL_LASTFRAG);
> + sc->dc_cdata.dc_tx_chain[cur] = sc->dc_cdata.dc_tx_mapping;
> if (sc->dc_flags & DC_TX_INTR_FIRSTFRAG)
> sc->dc_ldata->dc_tx_list[first].dc_ctl |=
> htole32(DC_TXCTL_FINT);
> @@ -3311,13 +3312,13 @@
> * of fragments or hit the end of the mbuf chain.
> */
> idx = sc->dc_cdata.dc_tx_prod;
> + sc->dc_cdata.dc_tx_mapping = *m_head;
> error = bus_dmamap_load_mbuf(sc->dc_mtag, sc->dc_cdata.dc_tx_map[idx],
> *m_head, dc_dma_map_txbuf, sc, 0);
> if (error)
> return (error);
> if (sc->dc_cdata.dc_tx_err != 0)
> return (sc->dc_cdata.dc_tx_err);
> - sc->dc_cdata.dc_tx_chain[idx] = *m_head;
> bus_dmamap_sync(sc->dc_mtag, sc->dc_cdata.dc_tx_map[idx],
> BUS_DMASYNC_PREWRITE);
> bus_dmamap_sync(sc->dc_ltag, sc->dc_lmap,
> Index: sys/pci/if_dcreg.h
> ===================================================================
> RCS file: /home/ncvs/src/sys/pci/if_dcreg.h,v
> retrieving revision 1.40
> diff -u -r1.40 if_dcreg.h
> --- sys/pci/if_dcreg.h 6 Dec 2003 02:29:31 -0000 1.40
> +++ sys/pci/if_dcreg.h 5 Jan 2004 19:58:05 -0000
> @@ -486,6 +486,7 @@
> struct dc_chain_data {
> struct mbuf *dc_rx_chain[DC_RX_LIST_CNT];
> struct mbuf *dc_tx_chain[DC_TX_LIST_CNT];
> + struct mbuf *dc_tx_mapping;
> bus_dmamap_t dc_rx_map[DC_RX_LIST_CNT];
> bus_dmamap_t dc_tx_map[DC_TX_LIST_CNT];
> u_int32_t *dc_sbuf;
Looks mostly good, but you missed some occurences of DC_TXCTL_FIRSTFRAG
that need to be changed.
Cheers,
Maxime
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