Re: [PATCH] net: cpts: Condition WARN_ON on PTP_1588_CLOCK

Richard Cochran
2020-04-20T21:18:25Z

On Mon, Apr 20, 2020 at 08:57:05PM +0200, Arnd Bergmann wrote:
> > d1cbfd771ce82 (Nicolas Pitre 2016-11-11 172) #if IS_REACHABLE(CONFIG_PTP_1588_CLOCK)
> > d1cbfd771ce82 (Nicolas Pitre 2016-11-11 173)
> > d1cbfd771ce82 (Nicolas Pitre 2016-11-11 174) /**
> > d1cbfd771ce82 (Nicolas Pitre 2016-11-11 175) * ptp_clock_register() - register a PTP hardware clock driver
> > d1cbfd771ce82 (Nicolas Pitre 2016-11-11 176) *
> > d1cbfd771ce82 (Nicolas Pitre 2016-11-11 177) * @info: Structure describing the new clock.
> > d1cbfd771ce82 (Nicolas Pitre 2016-11-11 178) * @parent: Pointer to the parent device of the new clock.
> > d1cbfd771ce82 (Nicolas Pitre 2016-11-11 179) *
> > d1cbfd771ce82 (Nicolas Pitre 2016-11-11 180) * Returns a valid pointer on success or PTR_ERR on failure. If PHC
> > d1cbfd771ce82 (Nicolas Pitre 2016-11-11 181) * support is missing at the configuration level, this function
> > d1cbfd771ce82 (Nicolas Pitre 2016-11-11 182) * returns NULL, and drivers are expected to gracefully handle that
> > d1cbfd771ce82 (Nicolas Pitre 2016-11-11 183) * case separately.
> > d1cbfd771ce82 (Nicolas Pitre 2016-11-11 184) */
>
> The key here is "gracefully". The second patch from Clay just turns NULL into
> -EOPNOTSUPP and treats the compile-time condition into a runtime error.

You are talking about the cpts driver, no?

I'm worried about ptp_clock_register(), because it does return NULL if
IS_REACHABLE(CONFIG_PTP_1588_CLOCK), and this is the "correct"
behavior ever since November 2016.

If somebody wants to change that stub to return EOPNOTSUPP, then fine,
but please have them audit the callers and submit a patch series.

Thanks,
Richard