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

[Roland Dreier]

    Grant> This sounds no different than say tulip driver which might
    Grant> claim multiple 100BT cards below different PCI Busses.

The difference is that not only can only a client have multiple
devices, but also a device can have multiple clients.  So PCI devices
can get away with a single slot to track driver context.

    Grant> I expect each client to have some data structure to track
    Grant> state info and each "parent" device must know something
    Grant> about it. Ie when the parent device goes away, each related
    Grant> client instance must be notified.  Or is that not true
    Grant> either?

There's a list of devices and a list of clients.  When a device is
added or removed, every client on the list gets a callback (ib_device
is sort of like class_device and ib_client is sort of like
class_interface in the driver model).

    Grant> I agree we can't avoid the dynamic allocation.  But we can
    Grant> choose when it happens.  I'm just questioning if it really
    Grant> needs to happen in get/set private data.  I'm thinking it
    Grant> should happen during some part of the initialization and
    Grant> removal of specific instances of a client.

Sure, we could allocate client context before we call the client back
for a device add (and just not even call the client back if the
allocation failed).  Does that seem better?

 - R.