Re: [PATCH v1] spi: Don't have controller clean up spi device before driver unbind

[Lukas Wunner <lukas@wunner.de>]

On Tue, May 04, 2021 at 08:14:16PM -0700, Saravana Kannan wrote:
> @@ -415,6 +421,7 @@ static int spi_remove(struct device *dev)
>  				 ERR_PTR(ret));
>  	}
>  
> +	spi_cleanup(to_spi_device(dev));
>  	dev_pm_domain_detach(dev, true);
>  
>  	return 0;

Unfortunately this doesn't look right:  spi_remove() is run on
driver unbind of the spi_device.  With the above change,
->setup is called on spi_device addition and ->cleanup is called
on unbind, which is obviously assymetric.  What can happen
here is that a slave-specific controller_state is allocated on
spi_device addition, then on unbind that controller_state is freed
and on a subsequent rebind it won't be recreated because ->setup
isn't run on spi_device ->probe.

As I've written yesterday, calling spi_cleanup() in
spi_unregister_device() should be fine if you move it to the end
of the function, but before the final put_device().  For that,
you need to open code the calls to device_del() and put_device()
that happen in device_unregister() so far.

Thanks,

Lukas