Re: [TEST FIX] Re: SSH Hangs in 2.5.59 and 2.5.55 but not 2.4.x, through Cisco PIX

David S. Miller
2003-01-28T20:37:37Z

From: Sebastian Benoit <benoit-lists@fb12.de>
Date: Tue, 28 Jan 2003 20:16:45 +0100

David S. Miller(davem@redhat.com)@2003.01.28 10:35:34 +0000:
> Good set of debug checks would be the following:

no output, i did 4 tests, everytime i was able to lock the ssh-connection
within a few seconds. kernel 2.5.59 + your debug-patch.

Thanks for testing, how about this new patch at the end of this email?
Does it make the problem go away?

Alexey, most solid report is that 2.5.43-bk1 makes bug appear.
This is good because it sort of narrows things down. What is
contained there in networking is:

1) initial stackable dst logic, should not cause problems
2) addition of UDP sendfile and ip_append_*() logic
3) fix to tcp_check_req() "fix" :-) it only changes bahevior
on connect so should not be a problem

I heavily, therefore, suspect #2 which is why I am poking around
in the tcp.c changes to change checksumming and copying semantics.

--- net/ipv4/tcp.c.~1~ Tue Jan 28 12:40:09 2003
+++ net/ipv4/tcp.c Tue Jan 28 12:41:48 2003
@@ -1089,11 +1089,13 @@
if (!skb)
goto wait_for_memory;

+#if 0
/*
* Check whether we can use HW checksum.
*/
if (sk->route_caps & (NETIF_F_IP_CSUM|NETIF_F_NO_CSUM|NETIF_F_HW_CSUM))
skb->ip_summed = CHECKSUM_HW;
+#endif

skb_entail(sk, tp, skb);
copy = mss_now;