From owner-freebsd-scsi  Wed Jun 30 21:17:19 1999
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Subject: Re: FreeBSD panics with Mylex DAC960SX
In-Reply-To: <199907010257.MAA30296@godzilla.zeta.org.au> from Bruce Evans at "Jul 1, 1999 12:57:43 pm"
To: bde@zeta.org.au (Bruce Evans)
Date: Wed, 30 Jun 1999 22:15:23 -0600 (MDT)
Cc: jgreco@ns.sol.net, wilko@yedi.iaf.nl, scsi@FreeBSD.ORG
From: "Kenneth D. Merry" <ken@plutotech.com>
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Bruce Evans wrote...
> >Now, based on some trace printf's I sprinkled in dscheck, it looks to
> >me like I get as far as
> >
> >if (bp->b_bcount % ssp->dss_secsize)
> >	goto bad_bcount;
> >
> >around line #191 of kern/subr_diskslice.c.  (you can see the "ckpt1c"
> >interspersed with other output if you look carefully).  It does not
> >hit the printf() right after that, so I am guessing that ssp->dss_secsize
> >is probably zero.
> 
> Try this "fix" for dsopen().  This should cause open() to fail before the
> sector size is used; in particular it should prevent divisions by sector
> sizes of 0.  I don't know how open() gets so far before the sector size is
> known.

I don't know either, but I intend to find out. :)

In any case, that "fix" might actually be useful to catch pathological
cases -- i.e. where the drive doesn't return an error for a read capacity,
but the data it returns is bogus.  (e.g. sector size of 0)

Ken
-- 
Kenneth Merry
ken@plutotech.com


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