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

[Greg KH <greg@kroah.com>]

On Tue, Oct 30, 2007 at 01:25:43PM -0500, James Bottomley wrote:
> On Mon, 2007-10-29 at 18:58 +0100, Stefan Richter wrote:
> > James Bottomley wrote:
> > >> >  struct attribute_group {
> > >> >  	const char		*name;
> > >> > +	int			(*filter_show)(struct kobject *, int);
> > 
> > > Actually, it returns a true/false value indicating whether the given
> > > attribute should be displayed.
> > 
> > How about this:
> > 
> > 	int (*is_visible)(...);
> 
> OK, so is this latest revision acceptable to everyone?
> 
> James
> 
> Index: BUILD-2.6/fs/sysfs/group.c
> ===================================================================
> --- BUILD-2.6.orig/fs/sysfs/group.c	2007-10-28 17:27:04.000000000 -0500
> +++ BUILD-2.6/fs/sysfs/group.c	2007-10-30 12:35:47.000000000 -0500
> @@ -16,25 +16,31 @@
>  #include "sysfs.h"
>  
>  
> -static void remove_files(struct sysfs_dirent *dir_sd,
> +static void remove_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
>  			 const struct attribute_group *grp)
>  {
>  	struct attribute *const* attr;
> +	int i;
>  
> -	for (attr = grp->attrs; *attr; attr++)
> -		sysfs_hash_and_remove(dir_sd, (*attr)->name);
> +	for (i = 0, attr = grp->attrs; *attr; i++, attr++)
> +		if (grp->is_visible &&
> +		    grp->is_visible(kobj, *attr, i))
> +			sysfs_hash_and_remove(dir_sd, (*attr)->name);

Hm, doesn't this break for the zillions of attribute groups that do not
have the is_visible function set?

> -static int create_files(struct sysfs_dirent *dir_sd,
> +static int create_files(struct sysfs_dirent *dir_sd, struct kobject *kobj,
>  			const struct attribute_group *grp)
>  {
>  	struct attribute *const* attr;
> -	int error = 0;
> +	int error = 0, i;
>  
> -	for (attr = grp->attrs; *attr && !error; attr++)
> -		error = sysfs_add_file(dir_sd, *attr, SYSFS_KOBJ_ATTR);
> +	for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++)
> +		if (grp->is_visible &&
> +		    grp->is_visible(kobj, *attr, i))
> +			error |=
> +				sysfs_add_file(dir_sd, *attr, SYSFS_KOBJ_ATTR);

Same problem here, if grp->is_visible is not set, sysfs_add_file() would
never be called, right?

Other than the logic problem (I think), I have no issue with this idea
at all.  Care to redo this so it works?

thanks,

greg k-h