Re: [PATCH] virtio: remove overzealous BUG_ON.

Rusty Russell wrote:[color=blue]
> The 'disable_cb' callback is designed as an optimization to tell the host
> we don't need callbacks now. As it is not reliable, the debug check is
> overzealous: it can happen on two CPUs at the same time. Document this.
>
> Even if it were reliable, the virtio_net driver doesn't disable
> callbacks on transmit so the START_USE/END_USE debugging reentrance
> protection can be easily tripped even on UP.
>
> Thanks to Balaji Rao for the bug report and testing.[/color]

I think the printk() in start_xmit should be removed too (or at least
rate limited).

Regards,

Anthony Liguori
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On Monday 07 April 2008 23:50:24 Anthony Liguori wrote:[color=blue]
> Rusty Russell wrote:[color=green]
> > The 'disable_cb' callback is designed as an optimization to tell the host
> > we don't need callbacks now. As it is not reliable, the debug check is
> > overzealous: it can happen on two CPUs at the same time. Document this.
> >
> > Even if it were reliable, the virtio_net driver doesn't disable
> > callbacks on transmit so the START_USE/END_USE debugging reentrance
> > protection can be easily tripped even on UP.
> >
> > Thanks to Balaji Rao for the bug report and testing.[/color]
>
> I think the printk() in start_xmit should be removed too (or at least
> rate limited).[/color]

Yep, please send patch. I'm about to jump on a plane, so consider this a
pre-canned ack.

Thanks,
Rusty.
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