lkml.org 
[lkml]   [2003]   [Dec]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: IDE-SCSI oops in 2.6.0-test11
On Tue, Dec 02 2003, Linus Torvalds wrote:
>
>
> On Tue, 2 Dec 2003 ross.alexander@uk.neceur.com wrote:
> >
> > I can't get the source, otherwise I would have compiled it against
> > 2.6.0. However I don't find this point particularly relevant since
> > 2.6.0 should be backward compatible with 2.4,0, atleast at the binary
> > level.
> >
> > I tried the earlier versions of dvdrtools and cdrtools and their didn't
> > like ide-cd. This version (cdrecord-dvdpro) does but it still don't
> > alter the fact that while using ide-scsi is no longer recommended, it
> > still should work.
>
> Well, we're trying, but nobody has had a lot of luck with it.
>
> However, your particular case looks pretty straightforward:
>
> > Here the the oops again.
> >
> > Dec 2 12:02:46 mig27 kernel: Unable to handle kernel NULL pointer dereference at virtual address 00000000
> > Dec 2 12:02:46 mig27 kernel: printing eip:
> > Dec 2 12:02:46 mig27 kernel: 00000000
>
> Somebody jumped through a NULL pointer, and it was:
>
> > Dec 2 12:02:46 mig27 kernel: Process cdrecord-prodvd (pid: 369, threadinfo=e4160000 task=f65d4100)
> > Dec 2 12:02:46 mig27 kernel: Call Trace:
> > Dec 2 12:02:46 mig27 kernel: [<f9859b1b>] idescsi_transfer_pc+0x11b/0x120 [ide_scsi]
>
> That's the code that does:
>
> ...
> if (test_bit (PC_DMA_OK, &pc->flags)) {
> set_bit (PC_DMA_IN_PROGRESS, &pc->flags);
> (void) (HWIF(drive)->ide_dma_begin(drive));
> }
> ...
>
> and it looks like the PC_DMA_OK flag is incorrect.
>
> Doing a bit more digging shows that "idescsi_issue_pc()" seems to use some
> variables without ever actually _initializing_ them. How about this
> trivial one-liner? Does that make it work for you?
>
> Jens? Comments?
>
> Linus
>
> ---
> ===== drivers/scsi/ide-scsi.c 1.33 vs edited =====
> --- 1.33/drivers/scsi/ide-scsi.c Tue Nov 18 23:40:45 2003
> +++ edited/drivers/scsi/ide-scsi.c Tue Dec 2 10:36:33 2003
> @@ -516,6 +516,7 @@
> pc->actually_transferred=0; /* We haven't transferred any data yet */
> pc->current_position=pc->buffer;
> bcount.all = IDE_MIN(pc->request_transfer, 63 * 1024); /* Request to transfer the entire buffer at once */
> + feature.all = 0;
>
> if (drive->using_dma && rq->bio) {
> if (test_bit(PC_WRITING, &pc->flags))

Your fix is correct Linus, the very same bug was fixed in 2.4 recently
as well.

--
Jens Axboe

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:59    [W:0.494 / U:0.016 seconds]
©2003-2014 Jasper Spaans. Advertise on this site