> Quoting Michael S. Tsirkin <[EMAIL PROTECTED]>:
> Subject: Re: [PATCH] IB/ipoib: fix thinko in packet length checks
>
> > Quoting Roland Dreier <[EMAIL PROTECTED]>:
> > Subject: Re: [PATCH] IB/ipoib: fix thinko in packet length checks
> >
> > This definitely looks like a problem, but I'm confused by this:
> >
> > > --- a/drivers/infiniband/ulp/ipoib/ipoib_cm.c
> > > +++ b/drivers/infiniband/ulp/ipoib/ipoib_cm.c
> > > @@ -452,7 +452,7 @@ void ipoib_cm_send(struct net_device *dev, struct
> > sk_buff *skb, struct ipoib_cm_
> > > skb->len, tx->mtu);
> > > ++priv->stats.tx_dropped;
> > > ++priv->stats.tx_errors;
> > > - ipoib_cm_skb_too_long(dev, skb, tx->mtu -
> > INFINIBAND_ALEN);
> > > + ipoib_cm_skb_too_long(dev, skb, tx->mtu -
> > IPOIB_ENCAP_LEN);
> > > return;
> > > }
> >
> > After this change, the code looks like:
> >
> > if (unlikely(skb->len > tx->mtu)) {
> > ipoib_warn(priv, "packet len %d (> %d) too long to send,
> > dropping\n",
> > skb->len, tx->mtu);
> > ++priv->stats.tx_dropped;
> > ++priv->stats.tx_errors;
> > ipoib_cm_skb_too_long(dev, skb, tx->mtu - IPOIB_ENCAP_LEN);
> > return;
> > }
> >
> > so why is the test against just tx->mtu, while ipoib_cm_skb_too_long()
> > is passed an mtu of tx->mtu - IPOIB_ENCAP_LEN?
>
> I actually copied this from datagram code.
>
> What ipoib_cm_skb_too_long does is set the dest MTU metric.
>
> So look at this logic in datagram mode:
> if (new_mtu > IPOIB_PACKET_SIZE - IPOIB_ENCAP_LEN) {
> return -EINVAL;
> }
>
> Why is the max MTU set to IPOIB_PACKET_SIZE - IPOIB_ENCAP_LEN and
> not to IPOIB_PACKET_SIZE?
And by the way, the chunk in the datagram part looks the same.
--
MST
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