Subject: Re: [PATCH 2/3] ptp: Add clock name to uevent

From: Greg Kroah-Hartman <[email-masked]>
Date: Tue, 15 Oct 2024 14:16:09 +0200

On Tue, Oct 15, 2024 at 02:02:17PM +0200, Sven Schnelle wrote:
> Greg Kroah-Hartman <[email-masked]> writes:
> 
> > On Tue, Oct 15, 2024 at 12:54:13PM +0200, Sven Schnelle wrote:
> >> To allow users to have stable device names with the help of udev,
> >> add the name to the udev event that is sent when a new PtP clock
> >> is available. The key is called 'PTP_CLOCK_NAME'.
> >
> > Where are you documenting this new user/kernel api you are adding?
> >
> >> 
> >> Signed-off-by: Sven Schnelle <[email-masked]>
> >> ---
> >>  drivers/ptp/ptp_clock.c | 11 ++++++++++-
> >>  1 file changed, 10 insertions(+), 1 deletion(-)
> >> 
> >> diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
> >> index c56cd0f63909..15937acb79c6 100644
> >> --- a/drivers/ptp/ptp_clock.c
> >> +++ b/drivers/ptp/ptp_clock.c
> >> @@ -25,9 +25,11 @@
> >>  #define PTP_PPS_EVENT PPS_CAPTUREASSERT
> >>  #define PTP_PPS_MODE (PTP_PPS_DEFAULTS | PPS_CANWAIT | PPS_TSFMT_TSPEC)
> >>  
> >> +static int ptp_udev_uevent(const struct device *dev, struct kobj_uevent_env *env);
> >>  const struct class ptp_class = {
> >>  	.name = "ptp",
> >> -	.dev_groups = ptp_groups
> >> +	.dev_groups = ptp_groups,
> >> +	.dev_uevent = ptp_udev_uevent
> >>  };
> >>  
> >>  /* private globals */
> >> @@ -514,6 +516,13 @@ EXPORT_SYMBOL(ptp_cancel_worker_sync);
> >>  
> >>  /* module operations */
> >>  
> >> +static int ptp_udev_uevent(const struct device *dev, struct kobj_uevent_env *env)
> >> +{
> >> +	struct ptp_clock *ptp = container_of(dev, struct ptp_clock, dev);
> >> +
> >> +	return add_uevent_var(env, "PTP_CLOCK_NAME=%s", ptp->info->name);
> >
> > Why is this needed?  Can't you get the name from the sysfs paths, the
> > symlink should be there already.
> 
> You mean the 'clock_name' attribute in sysfs?

Great, yes, it's right there.

> That would require to
> write some script to iterate over all ptp devices and check the name,
> or is there a way to match that in udev?

Yes there is.  Please use that :)

thanks,

greg k-h