? 2022/1/15 ??5:43, Michael S. Tsirkin ??:> A common pattern for device reset is currently:
> vdev->config->reset(vdev);
> .. cleanup ..
>
> reset prevents new interrupts from arriving and waits for interrupt
> handlers to finish.
>
> However if - as is common - the handler queues a work request which is
> flushed during the cleanup stage, we have code adding buffers / trying
> to get buffers while device is reset. Not good.
>
> This was reproduced by running
> modprobe virtio_console
> modprobe -r virtio_console
> in a loop, and this reasoning seems to apply to virtio mem though
> I could not reproduce it there.
>
> Fix this up by calling virtio_break_device + flush before reset.
>
> Signed-off-by: Michael S. Tsirkin <mst at redhat.com>
> ---
> drivers/virtio/virtio_mem.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
> index 38becd8d578c..33b8a118a3ae 100644
> --- a/drivers/virtio/virtio_mem.c
> +++ b/drivers/virtio/virtio_mem.c
> @@ -2888,6 +2888,8 @@ static void virtio_mem_remove(struct virtio_device
*vdev)
> virtio_mem_deinit_hotplug(vm);
>
> /* reset the device and cleanup the queues */
> + virtio_break_device(vdev);
> + flush_work(&vm->wq);
We set vm->removing to true and call cancel_work_sync() in
virtio_mem_deinit_hotplug(). Isn't is sufficient?
Thanks
> virtio_reset_device(vdev);
> vdev->config->del_vqs(vdev);
>