[ofa-general] rdma cm timeout option, was [iWARP issues]

[Sean Hefty]

>I still don't understand why you would want to do this. TCP already
>implements the best timer you could hope for.

Because TCP isn't running on top of IB.  And IB doesn't automatically establish
connections for the user on the passive side.

>But, if all you want to do is abort an in-progress connection attempt,
>can't you just run a timer to signal you and thereby interrupt the
>connect(2) in progress?

Yes - that's one of the options I'm considering.  But either the ULP can be
responsible for canceling the connection request, or the rdma cm can manage this
for the user.

These are the possibilities that I see:

1 Leave API unchanged.
2 Allow ULP to set number of connection retries.
3 Allow ULP to set connection timeout.
4 Allow ULP to set timeout per retry and number of retries.

The 1st option requires ULP to manage shorter timeouts.  From what I can tell,
the 2nd option matches a non-portable Linux setsockopt() capability.  The 3rd
and 4th options can be applied to IB connections, but do not easily extend to
iWarp.

Of these, I'm leaning towards the first option.  But this doesn't allow for
longer timeouts.

- Sean