Re: [PATCH v6 3/4] of: overlay: add per overlay sysfs attributes

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

On Wed, Oct 21, 2015 at 12:15:00AM +0300, Pantelis Antoniou wrote:
> Hi Greg,
> 
> > On Oct 21, 2015, at 00:08 , Greg Kroah-Hartman <gregkh@linuxfoundation.org> wrote:
> > 
> > On Tue, Oct 20, 2015 at 10:13:16PM +0300, Pantelis Antoniou wrote:
> >> * A per overlay can_remove sysfs attribute that reports whether
> >> the overlay can be removed or not due to another overlapping overlay.
> >> 
> >> * A target sysfs attribute listing the target of each fragment,
> >> in a group named after the name of the fragment.
> >> 
> >> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
> >> ---
> >> drivers/of/overlay.c | 103 +++++++++++++++++++++++++++++++++++++++++++++++++--
> >> 1 file changed, 99 insertions(+), 4 deletions(-)
> >> 
> >> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> >> index 067404e..2d51d9e2 100644
> >> --- a/drivers/of/overlay.c
> >> +++ b/drivers/of/overlay.c
> >> @@ -25,8 +25,23 @@
> >> 
> >> #include "of_private.h"
> >> 
> >> +/* fwd. decl */
> >> +struct of_overlay;
> >> +struct of_overlay_info;
> >> +
> >> +/* an attribute for each fragment */
> >> +struct fragment_attribute {
> >> +	struct attribute attr;
> >> +	ssize_t (*show)(struct kobject *kobj, struct fragment_attribute *fattr,
> >> +			char *buf);
> >> +	ssize_t (*store)(struct kobject *kobj, struct fragment_attribute *fattr,
> >> +			 const char *buf, size_t count);
> >> +	struct of_overlay_info *ovinfo;
> >> +};
> >> +
> >> /**
> >>  * struct of_overlay_info - Holds a single overlay info
> >> + * @info:	info node that contains the target and overlay
> >>  * @target:	target of the overlay operation
> >>  * @overlay:	pointer to the overlay contents node
> >>  *
> >> @@ -34,8 +49,13 @@
> >>  * records.
> >>  */
> >> struct of_overlay_info {
> >> +	struct of_overlay *ov;
> >> +	struct device_node *info;
> >> 	struct device_node *target;
> >> 	struct device_node *overlay;
> >> +	struct attribute_group attr_group;
> >> +	struct attribute *attrs[2];
> > 
> > Why both 2 attributes _and_ an attribute group?  Why not put the
> > attributes in the attribute group?
> > 
> > And why just one attribute group?  Why not an array of them like the
> > rest of the kernel is used to handle?
> > 
> 
> Because this makes it easier to add all the attributes for all the fragments in a single
> sysfs_create_groups() call, once for each overlay, instead of having a call to 
> sysfs_create_group() for each fragment of the overlay.
> 
> Reusing driver core helpers is good, no?

Yes it is, sorry, I missed how you used these later on, and the
attribute_groups usage there, nice job, sorry for the noise.

greg k-h