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, 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 <[email protected]> Cc: Herbert Xu <[email protected]> --- 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 @@ -47,9 +47,6 @@ struct virtnet_info struct napi_struct napi; unsigned int status; - /* The skb we couldn't send because buffers were full. */ - struct sk_buff *last_xmit_skb; - /* If we need to free in a timer, this is it. */ struct timer_list xmit_free_timer; @@ -116,9 +113,8 @@ static void skb_xmit_done(struct virtque /* We were probably waiting for more output buffers. */ netif_wake_queue(vi->dev); - /* Make sure we re-xmit last_xmit_skb: if there are no more packets - * queued, start_xmit won't be called. */ - tasklet_schedule(&vi->tasklet); + if (vi->free_in_tasklet) + tasklet_schedule(&vi->tasklet); } static void receive_skb(struct net_device *dev, struct sk_buff *skb, @@ -509,12 +505,7 @@ static void xmit_tasklet(unsigned long d struct virtnet_info *vi = (void *)data; netif_tx_lock_bh(vi->dev); - if (vi->last_xmit_skb && xmit_skb(vi, vi->last_xmit_skb) == 0) { - vi->svq->vq_ops->kick(vi->svq); - vi->last_xmit_skb = NULL; - } - if (vi->free_in_tasklet) - free_old_xmit_skbs(vi); + free_old_xmit_skbs(vi); netif_tx_unlock_bh(vi->dev); } @@ -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; + } - vi->last_xmit_skb = NULL; - - /* Put new one in send queue and do transmit */ - if (likely(skb)) { - __skb_queue_head(&vi->send, skb); - if (xmit_skb(vi, skb) != 0) { - vi->last_xmit_skb = skb; - skb = NULL; - goto stop_queue; - } - } -done: - vi->svq->vq_ops->kick(vi->svq); - return NETDEV_TX_OK; - -stop_queue: + /* Ring too full for this packet. */ pr_debug("%s: virtio not prepared to send\n", dev->name); netif_stop_queue(dev); @@ -557,12 +535,7 @@ stop_queue: netif_start_queue(dev); goto again; } - if (skb) { - /* Drop this skb: we only queue one. */ - vi->dev->stats.tx_dropped++; - kfree_skb(skb); - } - goto done; + return NETDEV_TX_BUSY; } static int virtnet_set_mac_address(struct net_device *dev, void *p) _______________________________________________ Virtualization mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/virtualization
