parallelize ifnet.if_addrhead

[Matthew Dillon]

:Hi,
:
:Following patch parallelizes ifnet.if_addrhead accessing
:Change ifnet.if_addrhead is serialized by netisr0
:
:Please review it:
:http://leaf.dragonflybsd.org/~sephe/ifaddr.diff5
:
:I have run this patch on all of my boxes for ~one month, so it should
:be safe to test, if your box is not two miles away from you :)
:
:Best Regards,
:sephe

    It looks reasonable.  I'm not sure if you are going to need a
    critical section inside ifa_iflink() and ifa_ifunlink().

    I'm a tad worried about ifa_iflink/unlink calls being made from
    interrupt threads.  It should work even with a migration race.

    The overhead will be nasty but those calls aren't in the critical
    path so as long as it works I think it is fine.

						-Matt