Re: kern/42662: iop driver makes kernel crash or freeze

[Aleksej Saushev <asau%inbox.ru@localhost>]

The following reply was made to PR kern/42662; it has been noted by GNATS.

From: Aleksej Saushev <asau%inbox.ru@localhost>
To: Manuel Bouyer <bouyer%antioche.eu.org@localhost>
Cc: gnats-bugs%NetBSD.org@localhost,  kern-bug-people%NetBSD.org@localhost,  
gnats-admin%NetBSD.org@localhost,  netbsd-bugs%NetBSD.org@localhost
Subject: Re: kern/42662: iop driver makes kernel crash or freeze
Date: Mon, 08 Feb 2010 20:21:09 +0300

 Manuel Bouyer <bouyer%antioche.eu.org@localhost> writes:
 
 > On Sat, Jan 30, 2010 at 06:42:37PM +0300, Aleksej Saushev wrote:
 >> I applied it to the current instead, it crashes with the same diagnostic
 >> message and similar backtrace, only it seems to do it a bit later.
 >> I can try to replace as many instances of the pattern as needed,
 >> can you recommend how many of them? All in that subroutine?
 >
 > All of them, mixing PRE and POST in bus_dma(9) is not allowed.
 > I also found one mistake where a PRE should have been a POST.
 > Please try the attached patch (still against netbsd-5).
 
 The following fixes the problem for me, I can boot installation CD and
 have access to disk storage (am able to read disklabel).
 
 --- sys/dev/i2o/iop.c  21 Oct 2009 21:12:05 -0000      1.77
 +++ sys/dev/i2o/iop.c  8 Feb 2010 17:19:57 -0000
 @@ -928,7 +928,7 @@
            BUS_DMASYNC_PREWRITE);
        memset(st, 0, sizeof(*st));
        bus_dmamap_sync(sc->sc_dmat, sc->sc_scr_dmamap, 0, sizeof(*st),
 -          BUS_DMASYNC_PREREAD|BUS_DMASYNC_POSTWRITE);
 +          BUS_DMASYNC_POSTWRITE);
  
        if ((rv = iop_post(sc, (u_int32_t *)&mf)) != 0)
                return (rv);
 @@ -993,7 +993,7 @@
            BUS_DMASYNC_PREWRITE);
        *sw = 0;
        bus_dmamap_sync(sc->sc_dmat, sc->sc_scr_dmamap, 0, sizeof(*sw),
 -          BUS_DMASYNC_PREREAD|BUS_DMASYNC_POSTWRITE);
 +          BUS_DMASYNC_POSTWRITE);
  
        if ((rv = iop_post(sc, mb)) != 0)
                return (rv);