On Sun, 2008-03-23 at 09:33 +0200, Or Gerlitz wrote:
> Eli Cohen wrote:
> > --- a/drivers/infiniband/ulp/ipoib/ipoib_ib.c
> > +++ b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
> > @@ -418,14 +449,35 @@ void ipoib_send(struct net_device *dev, struct
> > sk_buff *skb,
> > {
> > + int hlen;
> > + void *phead;
> > +
> > + if (!skb_is_gso(skb)) {
> > + if (unlikely(skb->len > priv->mcast_mtu + IPOIB_ENCAP_LEN)) {
> > + ipoib_warn(priv, "packet len %d (> %d) too long to
> > send, dropping\n",
> > + skb->len, priv->mcast_mtu + IPOIB_ENCAP_LEN);
> > + ++dev->stats.tx_dropped;
> > + ++dev->stats.tx_errors;
> > + ipoib_cm_skb_too_long(dev, skb, priv->mcast_mtu);
> > + return;
> > + }
> > + phead = 0;
> > + hlen = 0;
> > + } else {
> > + /*
> > + * LSO header is limited to max 60 bytes
> > + */
> > + if (unlikely((ip_hdr(skb)->ihl + tcp_hdr(skb)->doff) > 15)) {
> > + ipoib_warn(priv, "ip(%d) and tcp(%d) headers too long,
> > dropping skb\n",
> > + ip_hdr(skb)->ihl << 2, tcp_hdr(skb)->doff <<
> > 2);
> > + goto drop;
> > + }
> >
> is the 60 bytes being a limitation of the connectX HW, the Linux kernel
> stack or some "lso spec"?
> > + hlen = ((ip_hdr(skb)->ihl + tcp_hdr(skb)->doff) << 2) +
> > IPOIB_ENCAP_LEN;
> > + phead = skb->data;
It's an implementation decision - I assume that I will never get TSO
SKBs where the headers exceed 60 bytes.
> >
> Looking in e1000 tso code (eg
> http://lxr.linux.no/linux/drivers/net/e1000/e1000_main.c#L2884) I see
> that the header len is gotten by
> skb_transport_offset(skb) + tcp_hdrlen(skb), is that what
> ((ip_hdr(skb)->ihl + tcp_hdr(skb)->doff) << 2) gives?
It looks like I would get the same effect if I'd used e1000 style though
I'm not sure which approach is faster.
> > @@ -470,6 +521,12 @@ void ipoib_send(struct net_device *dev, struct sk_buff
> > *skb,
> > netif_stop_queue(dev);
> > }
> > }
> > + return;
> > +
> > +drop:
> > + ++dev->stats.tx_errors;
> > + dev_kfree_skb_any(skb);
> > + return;
> >
> shouldn't the tx_dropped counter be incremented here?
I am not sure. Does every erroneous tx packets imply incrementing the
drop counter too?
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