udp mpsafe

[Matthew Dillon]

:Hi all,
:
:Please review the devel^2 ~ devel^5 (inclusive) at:
:http://gitweb.dragonflybsd.org/~sephe/dragonfly.git/shortlog/refs/heads/devel
:
:The modification/accessing to the udbinfo is protected by two mechanism:
:1) netisr barrier, which prevents code running in netisr from
:accessing udbinfo when the modification is going to happen
:2) serializer, which prevents code not running in netisr (e.g. sysctl,
:interface detaching) from accessing udbinfo when the modification is
:going to happen
:
:1) makes the udp input/output path lock free.
:
:Best Regards,
:sephe

    I'm going to ask Peter to run your fixes on theshell.  He's been having
    UDP-related kqueue issues which might be fixed by this.

						-Matt