On Wed, 2008-06-18 at 15:55 +0100, Andrew Price wrote: > On 18/06/08 08:22, Johannes Berg wrote: > >> This also affects some http requests such as loading slashdot but not > >> others (perhaps small ones?) such as twitter API http requests. It does > >> not seem to affect connections to other machines on my LAN, only ones > >> over the internet. > >> > >> I've tried tcpdumping to get more info but when I run tcpdump the > >> connections work again (if a tiny bit slower). > > > > Can you try tcpdump with the -p flag? promisc mode might affect things. > > I tried using -p and it made the bug go away again. However, I have some > packet captures from running tcpdump on the router while the bug was > occuring and from loading them into wireshark it seems there are some > (suspected) retransmissions with bad checksums. I've posted my packet > captures here: > > http://sucs.org/~welshbyte/lw/tcpdump_bad0.pcap > http://sucs.org/~welshbyte/lw/tcpdump_bad1.pcap > http://sucs.org/~welshbyte/lw/tcpdump_good0.pcap > > The two 'bad' ones were captured on the router while the bug was > occuring. The 'good' one is for comparison and was captured on the > router like the others but while running tcpdump on my laptop made the > bug go away (I hope that makes sense). > > In all cases, the test was to ssh to a remote server. The two bad cases > were closed before the password prompt was reached and the good case was > ^C'd at the password prompt. > > I hope this helps, Thanks. Unfortunately, it's very hard to tell what is causing the bug, but Dave Miller and I analysed the problem and found it to be caused by a disconnect in thinking -- I assumed skb_header_cloned() would check for the full skb data (which seems to be called 'head' in some places), not just the header; he, on the other hand, wasn't aware of software encryption mangling it all so we never noticed that the commit you bisected it down to was wrong to start with. Hence, that commit is now reverted, see http://git.kernel.org/?p=linux/kernel/git/davem/net-2.6.git;a=commit;h=3a5be7d4b079f3a9ce1e8ce4a93ba15ae6d00111 johannes
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