Re: [PATCH net] ptp: Return -EINVAL on ptp_clock_register if required ops are NULL

[Jakub Kicinski <kuba@kernel.org>]

On Thu, 30 Oct 2025 11:08:32 -0700 Tim Hostetler wrote:
> ptp_clock should never be registered unless it stubs one of gettimex64()
> or gettime64() and settime64(). WARN_ON_ONCE and error out if either set
> of function pointers is null.
> 
> Cc: stable@vger.kernel.org
> Fixes: d7d38f5bd7be ("ptp: use the 64 bit get/set time methods for the posix clock.")

This needs to go to net-next without the tags above.
The check can only help with new drivers, old ones _must_ be fixed 
like gve was. Not registering a driver is a regression.

> Suggested-by: Kuniyuki Iwashima <kuniyu@google.com>
> Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
> Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
> Signed-off-by: Tim Hostetler <thostet@google.com>
> ---
>  drivers/ptp/ptp_clock.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
> index ef020599b771..0bc79076771b 100644
> --- a/drivers/ptp/ptp_clock.c
> +++ b/drivers/ptp/ptp_clock.c
> @@ -325,6 +325,10 @@ struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
>  	if (info->n_alarm > PTP_MAX_ALARMS)

->n_alarm check is also input validation, you should probably fold it
into your new WARN_ON_ONCE(). Either that or remove the WARN_ON_ONCE()
annotation below. As is the checks are inconsistent.

>  		return ERR_PTR(-EINVAL);
>  
> +	if (WARN_ON_ONCE((!info->gettimex64 && !info->gettime64) ||
> +			 !info->settime64))
> +		return ERR_PTR(-EINVAL);
> +