On (Tue) Mar 30 2010 [15:49:22], Rusty Russell wrote:
> The get_buf() API sets the second arg to the number of bytes *written*
> by the other side; in this case it should be zero as these are output buffers.
>
> lguest gets this right (obviously kvm's console doesn't), resulting in
> continual buildup of console writes.
>
> Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> To: Amit Shah <amit.shah@xxxxxxxxxx>
Acked-by: Amit Shah <amit.shah@xxxxxxxxxx>
> ---
> drivers/char/virtio_console.c | 10 +++-------
> 1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -415,20 +415,16 @@ static ssize_t send_buf(struct port *por
> out_vq->vq_ops->kick(out_vq);
>
> if (ret < 0) {
> - len = 0;
> + in_count = 0;
> goto fail;
> }
>
> - /*
> - * Wait till the host acknowledges it pushed out the data we
> - * sent. Also ensure we return to userspace the number of
> - * bytes that were successfully consumed by the host.
> - */
> + /* Wait till the host acknowledges it pushed out the data we sent. */
> while (!out_vq->vq_ops->get_buf(out_vq, &len))
> cpu_relax();
> fail:
> /* We're expected to return the amount of data we wrote */
> - return len;
> + return in_count;
> }
>
> /*
>
Amit
--
http://log.amitshah.net/
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