On Tue, 2002-08-13 at 15:58, kuznet@ms2.inr.ac.ru wrote: 

Very strange. We have similar phenomenon reported with TCP, by the way.
So, I have to assume that checksumming routine is wrong and does some shit
sort of relying on an uninitialized data.

I've added some debug printk's and found out that it's the call to
csum_fold that fails in skb_copy_and_csum_datagram_iovec.

skb_copy_and_csum_datagram_iovec is called from:

net/ipv6/raw.c:rawv6_recvmsg()
	if (skb->ip_summed==CHECKSUM_UNNECESSARY) {
		err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
	} else if (msg->msg_flags&MSG_TRUNC) {
		if ((unsigned short)csum_fold(skb_checksum(skb, 0, skb->len, skb->csum)))
			goto csum_copy_err;
		err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);
	} else {
		err = skb_copy_and_csum_datagram_iovec(skb, 0, msg->msg_iov);
		      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
		if (err == -EINVAL)
			goto csum_copy_err;
	}

This obviosly works with my old ISA ne2k clone but not with the tulip.
And the tcpdump looked ok

Does anyone else have an idea or suggestion I can try?

Alexey, when you had checksum problems, did you see invalid checksums in
tcpdump?

-- 
/Martin

Never argue with an idiot. They drag you down to their level, then beat
you with experience.