Re: [PATCH] virtio: remove overzealous BUG_ON. - Kernel

This is a discussion on Re: [PATCH] virtio: remove overzealous BUG_ON. - Kernel ; Rusty Russell wrote: > 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 ...

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Thread: Re: [PATCH] virtio: remove overzealous BUG_ON.

  1. Re: [PATCH] virtio: remove overzealous BUG_ON.

    Rusty Russell wrote:
    > 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.


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

    Regards,

    Anthony Liguori
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  2. Re: [PATCH] virtio: remove overzealous BUG_ON.

    On Monday 07 April 2008 23:50:24 Anthony Liguori wrote:
    > Rusty Russell wrote:
    > > 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.

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


    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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