RE: LID reconfiguration

[Jeff Roberson <jroberson-gUAg20sWgfgcWVvVuXF20w@public.gmane.org>]

On Mon, 16 Nov 2009, Sean Hefty wrote:

>> Is there an opensource example of using APM?  When I call ib_cm_send_lap()
>> the QP goes to some error state and my connections die.  Do I need to set
>> some QP attributes first?  I found a paper that describes the process but
>> does not contain sample code or any real details.
>
> Sending the LAP/APR only exchanges CM protocol messages.  You still need to
> modify the QP.  There's an old example program for the kernel that did APM, but
> it shouldn't be too hard to see what it did and convert it to a userspace app.
>
> See the cmpost sample in the test-apps branch of my rdma-dev.git tree.

Thank you.  This worked for me.  However, there seems to be some kind of 
race when the connection is first set up.  On the client if I call 
ib_cm_send_lap() immediately after ib_cm_send_rtu() returns successfully I 
get an EINVAL error.  If I delay for one second it works just fine. 
According to the spec the passive/server side can not send the lap so I 
can't send it in the rtu handler.  Presumably the call fails immediately 
after send_rtu because the server hasn't received that message yet?  Is 
this right?  Is there a way to do this cleanly without a delay?

I notice that if I create the initial attributes for the connection 
request with an alternate path specified the alt_path_state is still 
MIGRATED when I send rtu.  If I load a path after the connection is 
established I can fail back and forth without issue.

Thanks,
Jeff

>
http://www.openfabrics.org/git/?p=~shefty/rdma-dev.git;a=blob;f=drivers/infiniba
nd/util/cmpost/cmpost.c;h=99f1446af841fd34b50b7bdfce1360f741e10a63;hb=b5e668a9b6
d0f24d1a92e604e67c44f1452ea1e4
>
> - Sean
>
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