[openib-general] RFD: uverbs and hotplug

[Michael S. Tsirkin]

Hello, Roland, all!
How should hotplug work with uverbs?

Currently ib_uverbs_remove_one simply does class_device_unregister.
What will if an application has the device open?

Ideally, once the device is removed, applications
get an error code and so can close the device freeing
up any resources, and reopen another one.
However, with libmthca we have a page remapped into
the application memory and requests are posted there.

One idea is to replace the hardware page mapped into the
application with a map to zero page. This prevents
the application from accessing hardware that's not there
anymore, but does nothing to notify the application
that it needs to take action.

What do people think?
Thanks,

-- 
MST - Michael S. Tsirkin