> > +void i2c_free_slave_host_notify_device(struct i2c_client *client)
> > +{
> > +	i2c_slave_unregister(client);
> > +	kfree(client->dev.platform_data);
> > +	i2c_unregister_device(client);
> > +}
> > +EXPORT_SYMBOL_GPL(i2c_free_slave_host_notify_device);
> 
> Sidenote: With my recent series "i2c: slave: improve sanity checks when
> un-/registering" this code became NULL-safe (and IS_ERR safe, too).

Stupid me, it is not NULL safe. The functions are. But, we deregister
'client' on our own. It probably makes sense to add some sanity checking
of the parameters of the exported functions.