[openib-general] Re: RFC: cma: need rdma_unbind

[Caitlin Bestler]

openib-general-bounces at openib.org wrote:
> Michael S. Tsirkin wrote:
>> No. A socket is a 5 tuple (proto, local addr, local port, remote
>> addr, remote port).  unbind just says that you can reuse local
>> addresses, so e.g. a new connection request will connect to a new
>> socket. 
> 
> I understand.  But if both sides do this, then the local and
> remote ports become available for re-use, and a new
> connection between the systems could end up with the same tuple.
> 

Keep in mind that an iWARP QP CAN be re-used before the
5 tuple is eligible for re-use (i.e., the TCP layer connection
establishment is responsible for not initiating/accepting
a conflicting connection during the timewait period, but
the QP can be re-used instantly for another connection).

So we need to be careful to avoid requiring that the QP be
time-waited, merely allow it. If SDP wants to do this generically
it would probably be ok, since I don't think it would delay
the re-use of that many iWARP QPs.