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    SubjectRe: [PATCH] Bluetooth: virtio_bt: fix device removal
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    Hi Michael,

    >>> Device removal is clearly out of virtio spec: it attempts to remove
    >>> unused buffers from a VQ before invoking device reset. To fix, make
    >>> open/close NOPs and do all cleanup/setup in probe/remove.
    >>
    >> so the virtbt_{open,close} as NOP is not really what a driver is suppose
    >> to be doing. These are transport enable/disable callbacks from the BT
    >> Core towards the driver. It maps to a device being enabled/disabled by
    >> something like bluetoothd for example. So if disabled, I expect that no
    >> resources/queues are in use.
    >>
    >> Maybe I misunderstand the virtio spec in that regard, but I would like
    >> to keep this fundamental concept of a Bluetooth driver. It does work
    >> with all other transports like USB, SDIO, UART etc.
    >>
    >>> The cost here is a single skb wasted on an unused bt device - which
    >>> seems modest.
    >>
    >> There should be no buffer used if the device is powered off. We also don’t
    >> have any USB URBs in-flight if the transport is not active.
    >>
    >>> NB: with this fix in place driver still suffers from a race condition if
    >>> an interrupt triggers while device is being reset. Work on a fix for
    >>> that issue is in progress.
    >>
    >> In the virtbt_close() callback we should deactivate all interrupts.
    >>
    >
    > If you want to do that then device has to be reset on close,
    > and fully reinitialized on open.
    > Can you work on a patch like that?
    > Given I don't have the device such a rework is probably more
    > than I can undertake.

    so you mean move virtio_find_vqs() into virtbt_open() and del_vqs() into
    virtbt_close()?

    Or is there are way to set up the queues without starting them?

    However I am failing to understand your initial concern, we do reset()
    before del_vqs() in virtbt_remove(). Should we be doing something different
    in virtbt_close() other than virtqueue_detach_unused_buf(). Why would I
    keep buffers attached if they are not used.

    Regards

    Marcel

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