diff options
Diffstat (limited to 'drivers/net/virtio_net.c')
| -rw-r--r-- | drivers/net/virtio_net.c | 64 |
1 files changed, 40 insertions, 24 deletions
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 420388a4c5e8..effe8c685f77 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -1,4 +1,4 @@ -/* A simple network driver using virtio. +/* A network driver using virtio. * * Copyright 2007 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation * @@ -73,6 +73,7 @@ struct skb_vnet_hdr { struct virtio_net_hdr hdr; struct virtio_net_hdr_mrg_rxbuf mhdr; }; + unsigned int num_sg; }; static inline struct skb_vnet_hdr *skb_vnet_hdr(struct sk_buff *skb) @@ -442,23 +443,24 @@ again: return received; } -static void free_old_xmit_skbs(struct virtnet_info *vi) +static unsigned int free_old_xmit_skbs(struct virtnet_info *vi) { struct sk_buff *skb; - unsigned int len; + unsigned int len, tot_sgs = 0; while ((skb = vi->svq->vq_ops->get_buf(vi->svq, &len)) != NULL) { pr_debug("Sent skb %p\n", skb); __skb_unlink(skb, &vi->send); vi->dev->stats.tx_bytes += skb->len; vi->dev->stats.tx_packets++; + tot_sgs += skb_vnet_hdr(skb)->num_sg; kfree_skb(skb); } + return tot_sgs; } static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb) { - int num; struct scatterlist sg[2+MAX_SKB_FRAGS]; struct skb_vnet_hdr *hdr = skb_vnet_hdr(skb); const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest; @@ -502,13 +504,14 @@ static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb) else sg_set_buf(sg, &hdr->hdr, sizeof(hdr->hdr)); - num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1; - return vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb); + hdr->num_sg = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1; + return vi->svq->vq_ops->add_buf(vi->svq, sg, hdr->num_sg, 0, skb); } static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) { struct virtnet_info *vi = netdev_priv(dev); + int capacity; again: /* Free up any pending old buffers before queueing new ones. */ @@ -516,27 +519,40 @@ again: /* 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); - /* Don't wait up for transmitted skbs to be freed. */ - skb_orphan(skb); - nf_reset(skb); - return NETDEV_TX_OK; + capacity = xmit_skb(vi, skb); + + /* This can happen with OOM and indirect buffers. */ + if (unlikely(capacity < 0)) { + netif_stop_queue(dev); + dev_warn(&dev->dev, "Unexpected full queue\n"); + if (unlikely(!vi->svq->vq_ops->enable_cb(vi->svq))) { + vi->svq->vq_ops->disable_cb(vi->svq); + netif_start_queue(dev); + goto again; + } + return NETDEV_TX_BUSY; } - /* Ring too full for this packet, remove it from queue again. */ - pr_debug("%s: virtio not prepared to send\n", dev->name); - __skb_unlink(skb, &vi->send); - netif_stop_queue(dev); - - /* Activate callback for using skbs: if this returns false it - * means some were used in the meantime. */ - if (unlikely(!vi->svq->vq_ops->enable_cb(vi->svq))) { - vi->svq->vq_ops->disable_cb(vi->svq); - netif_start_queue(dev); - goto again; + vi->svq->vq_ops->kick(vi->svq); + /* Don't wait up for transmitted skbs to be freed. */ + skb_orphan(skb); + nf_reset(skb); + + /* Apparently nice girls don't return TX_BUSY; stop the queue + * before it gets out of hand. Naturally, this wastes entries. */ + if (capacity < 2+MAX_SKB_FRAGS) { + netif_stop_queue(dev); + if (unlikely(!vi->svq->vq_ops->enable_cb(vi->svq))) { + /* More just got used, free them then recheck. */ + capacity += free_old_xmit_skbs(vi); + if (capacity >= 2+MAX_SKB_FRAGS) { + netif_start_queue(dev); + vi->svq->vq_ops->disable_cb(vi->svq); + } + } } - return NETDEV_TX_BUSY; + + return NETDEV_TX_OK; } static int virtnet_set_mac_address(struct net_device *dev, void *p) |