"xfrm: Fix the gc threshold value for ipv4" broke my IPSec connections

[Damian Pietras <damianp@daper.net>]

I've recently upgraded from 3.4.x to 3.10.x and this broke my IPSec
setup in transport mode. The simplest test case is to setup few such
connections with few boxes like this:

spdadd 192.168.1.100 192.168.2.100 any -P out ipsec
           esp/transport//require
           ah/transport//require;

spdadd 192.168.2.100 192.168.1.100 any -P in ipsec
           esp/transport//require
           ah/transport//require;

Then set up an HTTP server on one box and run ab on the other box to
create come TCP connections:

ab -n 10000 -c 50 http://192.168.1.100/

Then the connect() call will very quickly start returning ENOBUFS. I
haven't seen anything wrong with my simple setup (just copy of
ipsec-howto.org in transport mode and pre shared keys) and started
bisecting. That way I found this commit to break my case:

703fb94ec58e0e8769380c2877a8a34aeb5b6c97
xfrm: Fix the gc threshold value for ipv4

Reverting it on 3.10.15 fixes my issue. This seems to be there from 3.7
and I don't really believe such simple case stayed broken for so long.
Em I missing something or there is really a bug?

If smeone is interested in details of this configuration and commands
I'm running, just let me know. This was reproduced with few VMs under XEN.

-- 
Damian Pietras