[openib-general] Re: userspace event reporting

[Michael S. Tsirkin]

Quoting r. Sean Hefty <sean.hefty at intel.com>:
> Subject: RE: userspace event reporting
> 
> >> one way to handle this is to have destruction flush events first, then
> >> perform the actual destroy...
> >
> >Right, what I was trying to say in the other thread was: walk the event
> >list and kill events for the id that is destroyed.
> >
> >Does this make more sense?
> 
> I think this is needed, just not sure if it's sufficient.  Suppose get_event()
> has retrieved an event for a cm_id and is returning the information to
> userspace.  The application is unaware that an event is pending and destroys the
> cm_id.  The uCM allows the destroy to proceed, since it's not yet aware of the
> event.  The get_event() begins executing userspace code.
> 
> How does the app or uCM locate the data structure associated with the cm_id?  If
> destroy succeeded, the structure could have been destroyed.  A solution is to
> block the destroy, but I'm not sure what would block it.
> 
> - Sean
> 

Are we talking about multithreaded app? 
So this is purely userspace issue - cant userspace just take some mutex
in get_event and destroy paths?

-- 
MST