Re: [PATCH] sysfs: add filter function to groups

[Kay Sievers <kay.sievers@vrfy.org>]

On Mon, 2007-10-29 at 10:16 -0500, James Bottomley wrote:
> In the SCSI transport classes (and soon to be in the AEN event
> subsystem) we have a lot of need for a grouping that doesn't include all
> files in the group.  We basically want to show capability by which file
> is present.  A classic example of this is the SPI transport class
> connected to the 53c700 card.  It's incapable of doing all of the modern
> LVD functions, so we don't show any of those capabilities in its sysfs
> directory.  However, we have a lot of horrible logic to generate
> separate per host groupings of attributes for this.  We would be able to
> use the standard sysfs group attributes *if* there were a way of
> filtering them so that certain attributes didn't appear.

Sounds fine.
 
> This patch is a first pass at adding a filter function to the group
> attributes, just to see how the idea flies.  If everyone's OK with this,
> I think the next thing that we might do is add bitmap functions (so
> every bit in the bitmap has a name, but also might not appear) to
> groups.

Bitmaps in the attribute groups?

>  struct attribute_group {
>  	const char		*name;
> +	int			(*filter_show)(struct kobject *, int);

Are you sure that you want to return an array index here, instead of the
actual attribute? Like:
  int (*filter_show)(struct kobject *kobj, struct attribute *attr);

The names "show" and "store" are the ususal file-operation names, and we
are not filtering a "show" here, right? Maybe "create", or "export", or
something else might be a better name?

Thanks,
Kay