Date: Sun, 13 Jan 2002 22:37:35 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: Michael Reifenberger <root@nihil.plaut.de> Cc: FreeBSD-Current <current@FreeBSD.ORG> Subject: Re: panic during fdisk'ing a md(4) device Message-ID: <20020113222214.X598-100000@gamplex.bde.org> In-Reply-To: <20020112130202.F451-100000@nihil>
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On Sat, 12 Jan 2002, Michael Reifenberger wrote:
> Hi,
> more input:
> The panic occurs in dsname() while dereferencing devsw(dev)->d_name.
> devsw(dev) gives NULL.
This was fairly clear from the panic message (the low fault address
is almost certainly for a null pointer + offset, and it's fairly clear
how dsname() gets a null pointer). Sorry I didn't reply earlier and
save you the work debugging this.
> The call to dsname() occurs from dkmodminor() defined in disklabel.h
> I've seen two calls to dsname, only the second one panics.
> Any thoughts?
dkmodminor() is supposed to modify a minor device that already has a
devswitch. Since dsname() in it panics, the problem is earlier when
the minor device is created without giving it a devswitch. Minor
devices are supposed to be created in a hierarchial order so that
this doesn't happen. E.g.,
ad0 in disk_create() (only ?)
ad0s1 now in dsopen()
ad0s2
ad0s2a now in dsopen()
...
I suggest adding printfs to make_dev() and makedev() to track the order.
The problem occurs when makedev() is called without a corresponding
make_dev().
Bruce
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