[PATCH v7 17/17] PCI/AER: Add sysfs attributes for log ratelimits

[Bjorn Helgaas]

On Wed, May 21, 2025 at 11:46:00AM +0100, Jonathan Cameron wrote:
> On Tue, 20 May 2025 16:50:34 -0500
> Bjorn Helgaas <helgaas at kernel.org> wrote:
> 
> > From: Jon Pan-Doh <pandoh at google.com>
> > 
> > Allow userspace to read/write log ratelimits per device (including
> > enable/disable). Create aer/ sysfs directory to store them and any
> > future aer configs.
> ...

> There is some relatively new SYSFS infra that I think will help
> make this slightly nicer by getting rid of the extra directory when
> there is nothing to be done with it.

> > +#define aer_ratelimit_burst_attr(name, ratelimit)			\
> > +	static ssize_t							\
> > +	name##_show(struct device *dev, struct device_attribute *attr,	\
> > +		    char *buf)						\
> > +{									\
> 
> A little odd looking to indent this less than the line above.

Yep, fixed.

> > +const struct attribute_group aer_attr_group = {
> > +	.name = "aer",
> > +	.attrs = aer_attrs,
> > +	.is_visible = aer_attrs_are_visible,
> > +};
> 
> There are a bunch of macros to simplify cases where
> a whole group is either enabled or not and make the group
> itself go away if there is nothing to be shown.
> 
> DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE() combined with
> SYSFS_GROUP_VISIBLE() around the assignment does what we
> want here I think.
> 
> Whilst we can't retrofit that stuff onto existing ABI
> as someone may be assuming directory presence, we can
> make sysfs less cluttered for new stuff.
> 
> Maybe I'm missing why that doesn't work here though!

Is this something we can fix later, or are we locking ourselves into
user-visible ABI that's hard to change?  I'm kind of against the wall
relative to the v6.16 merge window and haven't had time to dig into
this part.