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

[Cornelia Huck <cornelia.huck@de.ibm.com>]

On Tue, 30 Oct 2007 20:55:06 -0700,
Greg KH <greg@kroah.com> wrote:

> On Tue, Oct 30, 2007 at 01:25:43PM -0500, James Bottomley wrote:
> > 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?

Would it make more sense then to turn the meaning of the callback
around?

for (...) {
	if (grp->mask_out && grp->mask_out(kobj, *attr, i))
		continue;
	error |= sysfs_add_file(...);
}