[netmp] socket accesses

[Matthew Dillon]

:So, atomic or non-atomic op, if we race here, the mbufs can stay in the sockbuf
:for ever...

    The current code does not clean out the sockbuf when setting
    SS_CANTRCVMORE.  I think data already queued stays in there until read
    by userland or until the socket is closed.  So it shouldn't matter if
    an extra packet or two gets in there while the socket is still open.

:..
:> if (so->so_state & SS_CANTRCVMORE) {
:>         soisdisconnected(so);
:>         callout_reset(tp->tt_2msl, tcp_maxidle,
:>                       tcp_timer_2msl, tp);
:> }
:
:And if we race here, we'll never disconnect the socket.
:..
:Aggelos

    This code looks like an optimization to me.  It shouldn't matter whether
    the conditional occurs or not.  All it does is shortcut the FIN2 state
    because there are no longer any readers that might need data received
    during that state.

    If it misses the case it would be as if the user shutdown a microsecond
    after the remote end initiated a close sequence instead of a microsecond
    before.

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>