Re: BUG: Null pointer dereference in fs/open.c

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 24 Apr 2007 05:44:42 +0000 (GMT) William Heimbigner <icxcnika@mar.tar.cc> wrote:

> On Mon, 23 Apr 2007, Andrew Morton wrote:
> > On Tue, 24 Apr 2007 05:10:04 +0000 (GMT) William Heimbigner <icxcnika@mar.tar.cc> wrote:
> >
> >>> --- a/drivers/block/pktcdvd.c~packet-fix-error-handling
> >>> +++ a/drivers/block/pktcdvd.c
> >>> @@ -777,7 +777,8 @@ static int pkt_generic_packet(struct pkt
> >>> 		rq->cmd_flags |= REQ_QUIET;
> >>>
> >>> 	blk_execute_rq(rq->q, pd->bdev->bd_disk, rq, 0);
> >>> -	ret = rq->errors;
> >>> +	if (rq->errors)
> >>> +		ret = -EIO;
> >>> out:
> >>> 	blk_put_request(rq);
> >>> 	return ret;
> >>> _
> >>
> >> This patch fixes (or conceals?) the oops.
> >>
> >
> > Fixes.  But does the packet driver actually work OK for you?  Writes
> > files and stuff like that?
> >
> Short answer, no.
> 
> Long answer:
> # pktsetup 0 /dev/hdc
>
> ...
>
> [11508.520800] pktcdvd: pkt_get_last_written failed
> 
> # mkudffs /dev/pktcdvd/0
> [11539.953560] pktcdvd: pkt_get_last_written failed
> trying to change type of multiple extents
> 
> I get the same error with /dev/hdd as well (hdc and hdd are both dvd 
> burners, hdd has a cd-rw and hdc had a dvd-rw)

Yes, I get the same on a sata (piix) dvd burner.

We need to work out who is setting rq->errors and why - should be pretty
simple.  I'll take a look at that after I've nailed one of these other bugs
over here.