[openib-general] Proposed device enumeration & async event APIs

[Roland Dreier]

    Fab> This sounds sane.  Are existing device notifications invoked
    Fab> from the thread context of the ib_register_client function?
    Fab> In other words, does the ib_register_client function return
    Fab> before or after the client has receive notifications of
    Fab> existing events?  Does ib_unregister_client synchronize with
    Fab> callback delivery?  Does ib_unregister_client send "pretend"
    Fab> removal events?

Yes to all of these questions.  Basically register does:

    lock device list
    add client to client list
    generate add callbacks for existing devices
    unlock device list

and unregister does

    lock device list
    remove client from client list
    generate remove callbacks for existing
    unlock device list

Adding a device does

    lock device list
    add device to device list
    generate add callbacks for existing clients
    unlock device list

and removing a device does

    lock device list
    remove device from device list
    generate add callbacks for existing clients
    unlock device list

So everything is synchronized by the lock and all fake events are generated.

    Fab> Why does ib_register_event_handler take a device as input?
    Fab> Is this device the same as event_handler.device?  Why not
    Fab> just use the event handler's device instead?

No good reason -- in fact I'll get rid of the parameter.

Thanks for the comments.

 - Roland