> 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?
--
MST
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