Re: [PATCH 3/4] virtio-input: Fix probe failed when modprobe virtio_input

[Michael S. Tsirkin]

On Mon, Nov 28, 2022 at 10:10:04AM +0800, Li Zetao wrote:
> When doing the following test steps, an error was found:
>   step 1: modprobe virtio_input succeeded
>     # modprobe virtio_input      <-- OK
> 
>   step 2: fault injection in input_allocate_device()
>     # modprobe -r virtio_input   <-- OK
>     # ...
>       CPU: 0 PID: 4260 Comm: modprobe Tainted: G        W
>       6.1.0-rc6-00285-g6a1e40c4b995-dirty #109
>       Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
>       Call Trace:
>        <TASK>
>        should_fail.cold+0x5/0x1f
>        ...
>        kmalloc_trace+0x27/0xa0
>        input_allocate_device+0x43/0x280
>        virtinput_probe+0x23b/0x1648 [virtio_input]
>        ...
>        </TASK>
>       virtio_input: probe of virtio5 failed with error -12
> 
>   step 3: modprobe virtio_net failed
>     # modprobe virtio_input       <-- failed
>       virtio_input: probe of virtio1 failed with error -2
> 
> The root cause of the problem is that the virtqueues are not
> stopped on the error handling path when input_allocate_device()
> fails in virtinput_probe(), resulting in an error "-ENOENT"
> returned in the next modprobe call in setup_vq().
> 
> virtio_pci_modern_device uses virtqueues to send or
> receive message, and "queue_enable" records whether the
> queues are available. In vp_modern_find_vqs(), all queues
> will be selected and activated, but once queues are enabled
> there is no way to go back except reset.
> 
> Fix it by reset virtio device on error handling path. After
> virtinput_init_vqs() succeeded, all virtqueues should be
> stopped on error handling path.
> 
> Fixes: 1fcf0512c9c8 ("virtio_pci: modern driver")

Probably 271c865161c57cfabca45b93eaa712b19da365bc


> Signed-off-by: Li Zetao <lizetao1@xxxxxxxxxx>
> ---
>  drivers/virtio/virtio_input.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c
> index 3aa46703872d..f638f1cd3531 100644
> --- a/drivers/virtio/virtio_input.c
> +++ b/drivers/virtio/virtio_input.c
> @@ -330,6 +330,7 @@ static int virtinput_probe(struct virtio_device *vdev)
>  err_mt_init_slots:
>  	input_free_device(vi->idev);
>  err_input_alloc:
> +	virtio_reset_device(vdev);
>  	vdev->config->del_vqs(vdev);
>  err_init_vq:
>  	kfree(vi);
> -- 
> 2.25.1