Re: [PATCH 0/2] Add device_create_files() and device_remove_files() helpers

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Jan 28, 2015 at 10:26:28PM +0100, Takashi Iwai wrote:
> At Wed, 28 Jan 2015 13:05:47 -0800,
> Greg Kroah-Hartman wrote:
> > 
> > On Wed, Jan 28, 2015 at 09:46:12PM +0100, Takashi Iwai wrote:
> > > Hi,
> > > 
> > > this is a simple patch to add device_create_files() and
> > > device_remove_files() to replace multiple device_create_file() or
> > > _remove() calls with a single shot with the device_attr list.
> > > 
> > > It's basically just a clean up, but also helps to simplify the error
> > > handling a lot in many existing codes since the function itself does
> > > rollback at error.
> > > 
> > > The series contains a patch to apply these to drivers/base/node.c.
> > > I have lots of patches (up to 30) to use these in the whole tree, but
> > > maybe it'd be easier too apply once after this stuff is merged at
> > > first.  It's just a cleanup so no urgent task, after all.
> > 
> > I'd like to some day be able to drop device_create_file entirely, as it
> > is almost always used in a racy way (but not always, so we can't get rid
> > of it today.)
> > 
> > A driver should be using an attribute group and be created/registered
> > with it if they want any files associated with it, so giving people the
> > ability to add large numbers of files all at once seems like the wrong
> > thing to do :)
> 
> Well, through the glance over many codes using device_create_file(),
> I think the problem of the attribute group is that there is little
> help for generating the entries dynamically.  For example, if you have
> two groups you want to enable conditionally, what would be the best
> way to implement?

Use the is_visable() function callback, that's what it is there for.

thanks,

greg k-h