Re: [PATCH] virtio_console: free unused buffers with virtio port

Michael S. Tsirkin
2019-03-04T19:25:38Z

On Mon, Mar 04, 2019 at 06:35:11PM +0530, Pankaj Gupta wrote:
> The commit a7a69ec0d8e4 ("virtio_console: free buffers after reset")
> deffered detaching of unused buffer to virtio device unplug time.
>
> This causes unplug/replug of single port in virtio device with an
> error "Error allocating inbufs\n". As we don't free the unused buffers
> attached with the port. Re-plug the same port tries to allocate new
> buffers in virtqueue and results in this error if queue is full.
>
> This patch removes the unused buffers in vq's when we unplug the port.
> This is the best we can do as we cannot call device_reset because virtio
> device is still active. This was the working behaviour before the change
> introduced in commit b3258ff1d6.
>
> Reported-by: Xiaohui Li <xiaohli@redhat.com>
> Fixes: b3258ff1d6 ("virtio_console: free buffers after reset")
> Signed-off-by: Pankaj Gupta <pagupta@redhat.com>

I think if you do this you need to add support
in the packed ring.

> ---
> drivers/char/virtio_console.c | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index fbeb71953526..5fbf2ac73111 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -1506,15 +1506,25 @@ static void remove_port(struct kref *kref)
> kfree(port);
> }
>
> +static void remove_unused_bufs(struct virtqueue *vq)
> +{
> + struct port_buffer *buf;
> +
> + while ((buf = virtqueue_detach_unused_buf(vq)))
> + free_buf(buf, true);
> +}
> +
> static void remove_port_data(struct port *port)
> {
> spin_lock_irq(&port->inbuf_lock);
> /* Remove unused data this port might have received. */
> discard_port_data(port);
> + remove_unused_bufs(port->in_vq);
> spin_unlock_irq(&port->inbuf_lock);
>
> spin_lock_irq(&port->outvq_lock);
> reclaim_consumed_buffers(port);
> + remove_unused_bufs(port->out_vq);
> spin_unlock_irq(&port->outvq_lock);
> }
>
> @@ -1950,11 +1960,9 @@ static void remove_vqs(struct ports_device *portdev)
> struct virtqueue *vq;
>
> virtio_device_for_each_vq(portdev->vdev, vq) {
> - struct port_buffer *buf;
>
> flush_bufs(vq, true);
> - while ((buf = virtqueue_detach_unused_buf(vq)))
> - free_buf(buf, true);
> + remove_unused_bufs(vq);
> }
> portdev->vdev->config->del_vqs(portdev->vdev);
> kfree(portdev->in_vqs);
> --
> 2.20.1