Re: [patch] ata: libata: add per device private data

[Jeff Garzik <jgarzik@pobox.com>]

Kristen Carlson Accardi wrote:
> Allow host controllers to store private data per device.
> 
> Signed-off-by:  Kristen Carlson Accardi <kristen.c.accardi@intel.com>
> 
> ---
>  include/linux/libata.h |    3 +++
>  1 file changed, 3 insertions(+)
> 
> Index: libata-dev/include/linux/libata.h
> ===================================================================
> --- libata-dev.orig/include/linux/libata.h	2007-09-24 16:13:33.000000000 -0700
> +++ libata-dev/include/linux/libata.h	2007-09-24 16:15:24.000000000 -0700
> @@ -474,6 +474,9 @@ struct ata_device {
>  	/* error history */
>  	struct ata_ering	ering;
>  	int			spdn_cnt;
> +
> +	/* controller driver per device private data */
> +	void 			*private_data;

I don't have any objections to this per se...  a lot of other subsystems 
do this too, and I can certainly see a potential need.

But what about object lifetimes?  If a controller is hot-unplugged, does 
anyone need notification to destroy dynamic objects, or does controller 
cleanup take care of that?  If a device is unplugged, where should a 
controller driver do its ->private_data cleanup?

This is /not/ a NAK, just a request to make clear the lifetime rules and 
procedures...

	Jeff