On Tue, May 21, 2019 at 11:44:07AM +0200, Stefano Garzarella wrote:
> Hi Micheal, Jason,
> as suggested by Stefan, I'm checking if we have some races in the
> virtio-vsock driver. We found some races in the .probe() and .remove()
> with the upper layer (socket) and I'll fix it.
>
> Now my attention is on the bottom layer (virtio device) and my question is:
> during the .remove() of virtio-vsock driver (virtio_vsock_remove), could
> happen
> that an IRQ comes and one of our callback (e.g. virtio_vsock_rx_done()) is
> executed, queueing new works?
>
> I tried to follow the code in both cases (device unplugged or module removed)
> and maybe it couldn't happen because we remove it from bus's knowledge,
> but I'm not sure and your advice would be very helpful.
>
> Thanks in advance,
> Stefano
Great question! This should be better documented: patches welcome!
Here's my understanding:
A typical removal flow works like this:
- prevent linux from sending new kick requests to device
and flush such outstanding requests if any
(device can still send notifications to linux)
- call
vi->vdev->config->reset(vi->vdev);
this will flush all device writes and interrupts.
device will not use any more buffers.
previously outstanding callbacks might still be active.
- Then call
vdev->config->del_vqs(vdev);
to flush outstanding callbacks if any.
--
MST
