Messages in this thread | | | Subject | Re: [PATCH] Bluetooth: virtio_bt: fix device removal | From | Marcel Holtmann <> | Date | Thu, 25 Nov 2021 21:02:01 +0100 |
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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.
Regards
Marcel
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