[PATCH WIP/RFC v2 6/6] nvme-rdma: use ib_client API to detect device removal

[Sagi Grimberg]

>> Will this code work?
>>
>> 	mutex_lock(&nvme_rdma_ctrl_mutex);
>> 	list_for_each_entry(ctrl, &nvme_rdma_ctrl_list, list) {
>> 		if (ctrl->device->dev != ib_device)
>> 			continue;
>>
>> 		__nvme_rdma_del_ctrl(ctrl);
>> 	}
>> 	mutex_unlock(&nvme_rdma_ctrl_mutex);
>>
>> 	flush_workqueue(nvme_rdma_wq);
>
> I'll try this.  It is cleaner/easier to understand.
>
> I'm also moving the controller list to per-device as Christoph recommends.

I'm still not sure if it's a real must. This will only save us the
condition (as we'll get the device in the client data)