[PATCH v2 1/3] RDMA/core: make ib_device.add method optional

[Sagi Grimberg]

> ib_clients can indeed fill .add to NULL, but then they will not see
> any device removal notifications. The reason is that that
> ib_register_client and ib_register_device checked existence of .add
> before adding the creating a corresponding client_data and adding
> it to the list. Simple condition reverse fixes the issue.
> 
> Reviewed-by: Johannes Thumshirn <jthumshirn at suse.de>
> Reviewed-by: Christoph Hellwig <hch at lst.de>
> Signed-off-by: Sagi Grimberg <sagi at grimberg.me>

Any RDMA folks?