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SubjectRe: 'bad: scheduling while atomic!', preempt kernel, 2.6.1-test11, reading an apparently duff DVD-R
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On Mon, Dec 15, 2003 at 10:54:11AM -0500, Jeff Garzik wrote:
> Linus Torvalds wrote:
> >
> >On Mon, 15 Dec 2003, Toad wrote:
> >
> >>I got the following when trying to mount a particular DVD-R on Linux
> >>2.6.0-test11, using an IDE DVD-RW drive, using SCSI emulation, with the
> >>preempt kernel option enabled, and taskfile I/O:
> >>(the middle bit was repeated several times):
> >
> >
> >ide-scsi does
> >
> > spin_lock_irqsave(&ide_lock, flags);
> > while (HWGROUP(drive)->handler) {
> > HWGROUP(drive)->handler = NULL;
> > schedule_timeout(1);
> > }
> >
> >which is obvious crap. Scheduling while holding a spinlock is not a good
> >idea.
> >
> >You could try dropping the lock over the schedule and re-aquire it
> >afterwards, but the comment tries to say that it is required for avoiding
> >new requests.
> >
> >This is why ide-scsi needs a maintainer, btw - somebody who cares about
> >it, and actually tries to resolve the current mess.
>
>
> Pardon me for asking a dumb and possibly impertinent question, but why
> keep it around at all?
>
> In 2.6 it just seems like it's causing more problems than it's worth. I
> mean, replacing ide-scsi with a simple 4-line driver would suffice...
>
> int init_module(void)
> {
> printk(KERN_INFO "fix your app to use SG_IO\n");
> }
>
> Since the major app, cdrecord, has already been fixed, that just leaves
> a few IMO minor apps out there that (a) should be using SG IO and (b)
> are depending on an unmaintained and perpetually broken driver anyway.

I've been completely unable to get cdrtools to compile... The version in
debian is 2.0a19, which works with IDE-SCSI, and doesn't work without
it. The RPM from the oss-dvd extension site doesn't work either without
IDE-SCSI. Nor does dvd+rwtools. Anyone attempting to write DVDs will
have real problems if IDE-SCSI is removed, judging by this experience.
>
> Jeff
>
>
> P.S. Yes, libata will probably (not definite) use the SCSI layer to
> drive ATAPI devices... but that's a long way off, and will not be using
> the ide-scsi code. ide-scsi is basically a glue driver specifically for
> drivers/ide.
>

--
Matthew J Toseland - toad@amphibian.dyndns.org
Freenet Project Official Codemonkey - http://freenetproject.org/
ICTHUS - Nothing is impossible. Our Boss says so.
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