On Fri, 2009-05-29 at 23:46 +0930, Rusty Russell wrote:
> This effectively reverts 99ffc696d10b28580fe93441d627cf290ac4484c
> "virtio: wean net driver off NETDEV_TX_BUSY".
>
> The complexity of queuing an skb (setting a tasklet to re-xmit) is
> questionable,
It certainly adds some subtle complexities to start_xmit()
> especially once we get rid of the other reason for the
> tasklet in the next patch.
>
> If the skb won't fit in the tx queue, just return NETDEV_TX_BUSY. It
> might be frowned upon, but it's common and not going away any time
> soon.
>
> Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/net/virtio_net.c | 49 ++++++++++-------------------------------------
> 1 file changed, 11 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
>
> @@ -526,27 +517,14 @@ again:
> /* Free up any pending old buffers before queueing new ones. */
> free_old_xmit_skbs(vi);
>
> - /* If we has a buffer left over from last time, send it now. */
> - if (unlikely(vi->last_xmit_skb) &&
> - xmit_skb(vi, vi->last_xmit_skb) != 0)
> - goto stop_queue;
> + /* Put new one in send queue and do transmit */
> + __skb_queue_head(&vi->send, skb);
> + if (likely(xmit_skb(vi, skb) == 0)) {
> + vi->svq->vq_ops->kick(vi->svq);
> + return NETDEV_TX_OK;
> + }
Hmm, is it okay to leave the skb on the send queue if we return
NETDEV_TX_BUSY?
Cheers,
Mark.
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