Re: [PATCH 34/54] Driver Core: add kobj_attribute handling

Kay Sievers
2007-11-05T17:28:27Z

On Mon, 2007-11-05 at 09:11 -0800, Greg KH wrote:
> On Mon, Nov 05, 2007 at 05:23:32PM +0100, Kay Sievers wrote:
> > On Mon, 2007-11-05 at 13:42 +0100, Cornelia Huck wrote:
> > > On Fri, 2 Nov 2007 16:59:12 -0700,
> > > Greg Kroah-Hartman <gregkh@suse.de> wrote:
> > >
> > > > From: Kay Sievers <kay.sievers@vrfy.org>
> > > >
> > > > Add kobj_sysfs_ops to replace subsys_sysfs_ops. There is no
> > > > need for special kset operations, we want to be able to use
> > > > simple attribute operations at any kobject, not only ksets.
> > > >
> > > > The whole concept of any default sysfs attribute operations
> > > > will go away with the upcoming removal of subsys_sysfs_ops.
> > > >
> > > > Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
> > > > Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
> > > > ---
> > > > include/linux/kobject.h | 10 ++++++++++
> > > > lib/kobject.c | 29 +++++++++++++++++++++++++++++
> > > > 2 files changed, 39 insertions(+), 0 deletions(-)
> > >
> > > How about adding some simple wrappers around the new kobj_attribute
> > > structure? This makes the layering clearer.
> >
> > > +#define KOBJ_ATTR(_name,_mode,_show,_store) \
> > > + struct kobj_attribute kobj_attr_##_name = \
> > > + __ATTR(_name,_mode,_show,_store)
> >
> > That sounds fine.
> >
> > > +extern int __must_check kobject_create_file(struct kobject *,
> > >
> > > struct kobj_attribute *);
> > > +extern void kobject_remove_file(struct kobject *,struct kobj_attribute *);
> >
> > That should usually be done by default attributes assigned to the ktype.
> > Do you have a good use case, where people need to create such attributes
> > individually instead?
>
> The s390 code that was converted to use kobj_attributes :)
>
> These look very useful, I'll go add them to the series unless Kay really
> objects.

I just want to hear a good reason to create attributes individually. :)
Especially in conjunction with kobject_register(), these attributes are
not available at uevent time, which is really really bad.

Default attributes just work fine, and have the proper error handling
built-in. Offering special functions for it, may just encourage people
to continue this "broken" way of creating attributes.

So I really object, unless we get a good example why it's needed. :)

Kay