cvs commit: src/sys/kern uipc_socket.c
alfred at freebsd.org
Wed Mar 15 13:55:22 UTC 2006
1) apologies for top posting
2) cool, thanks for the explanation, I wasn't aware that this was
a cleanup step and was hoping it wasn't another ad-hoc reference
counting "fix". This looks good.
* Robert Watson <rwatson at FreeBSD.org> [060315 05:48] wrote:
> Socket and PCB reference counting is currently Extraordinarily Complex and
> More Than A Little Broken. This is the first in a long series of steps to
> migrate the socket and protocol code from an ad hoc reference system to a
> more pure reference system. This includes:
> - Transitioning so_pcb to being a protocol-only field, instead of allowing
> socket layer to use it. SS_PROTOREF is, in effect, replacing so_pcb as a
> reference visible to the socket layer.
> - Moving towards an invariant that so_pcb is non-NULL for the life time of a
> socket for most protocol, allowing us to remove the constant checking for
> NULL so_pcb (and associated locking) throughout the protocols. This
> involves a significant rewrite of TCP's pcb use, as we currently discard
> PCB long before the socket is freed, hence significant complexity in all
> TCP protocol APIs exposed to the socket layer.
> - Guaranteeing that pru_detach() will only be called once per socket, and
> if pru_attach() succeeded.
> - Eliminating unused failure modes, such as the failure of pru_detach() and
> - Fixing a large number of race conditions and bugs in the TCP tcpcb and
> I would like to get to the point where so_count is the sole reference count
> on the socket, but it will take quite a bit of work to get there. You can
> find an outstanding, if somewhat dated, patch at:
> Cleaning up and merging large parts of this is waiting on a couple of
> things, including updates to the bluetooth code (I've contacted emax
> already), and also on a determination of the future of netatm. I have
> changes in that patch to make netatm compile, but I'm unable to test it,
> and fairly sure there is more to be done there.
> Robert N M Watson
- Alfred Perlstein
- CTO Okcupid.com / FreeBSD Hacker / All that jazz -
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