On Thu, Feb 08, 2001 at 10:12:14PM +0100, David Brownell wrote:
> I just got a report of a symptom, likely related, where
> tcpdump shows the ACK is getting sent and then dropped.
> (Below, it's not even getting sent.) And in fact, I just saw
> this version a few moments ago myself.
This usually points to checksum problems. tcpdump doesn't check checksums.
> I've seen this problem with this driver off and on since
> about test8; it might have been there in test6/test7 when
> the driver was first developed (it's still "experimental")
> without being noticed ("intermittent"), but in any case
> this is rather perplexing. What do folk do when trying
> to get TCP to tell them what's up? Enabling TCP_DEBUG
> or NETDEBUG is no help at all.
Add printks or ktrace calls until you get enlighted.
You could e.g. instrument __kfree_skb to see where it is freed
(using __builtin_return_address(0) when you're using the right compiler)
This is like TV. I don't like TV.