linux-kernel - Re: [patch 01/13] ptp: Split out PTP_CLOCK

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Message-ID: <fde40e1e-5950-441c-a5c0-fbe25e0bb918@linux.dev>
Date: Sat, 21 Jun 2025 21:22:57 +0100
From: Vadim Fedorenko <vadim.fedorenko@...ux.dev>
To: Thomas Gleixner <tglx@...utronix.de>, LKML <linux-kernel@...r.kernel.org>
Cc: Richard Cochran <richardcochran@...il.com>, netdev@...r.kernel.org
Subject: Re: [patch 01/13] ptp: Split out PTP_CLOCK_GETCAPS ioctl code

On 20/06/2025 14:24, Thomas Gleixner wrote:
> ptp_ioctl() is an inpenetrable letter soup with a gazillion of case (scope)
> specific variables defined at the top of the function and pointless breaks
> and gotos.
> 
> Start cleaning it up by splitting out the PTP_CLOCK_GETCAPS ioctl code into
> a helper function. Use a argument pointer with a single sparse compliant
> type cast instead of proliferating the type cast all over the place.
> 
> No functional change intended.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> ---
>   drivers/ptp/ptp_chardev.c |   41 +++++++++++++++++++++++------------------
>   1 file changed, 23 insertions(+), 18 deletions(-)
> 
> --- a/drivers/ptp/ptp_chardev.c
> +++ b/drivers/ptp/ptp_chardev.c
> @@ -157,6 +157,26 @@ int ptp_release(struct posix_clock_conte
>   	return 0;
>   }
>   
> +static long ptp_clock_getcaps(struct ptp_clock *ptp, void __user *arg)
> +{
> +	struct ptp_clock_caps caps = {
> +		.max_adj		= ptp->info->max_adj,
> +		.n_alarm		= ptp->info->n_alarm,
> +		.n_ext_ts		= ptp->info->n_ext_ts,
> +		.n_per_out		= ptp->info->n_per_out,
> +		.pps			= ptp->info->pps,
> +		.n_pins			= ptp->info->n_pins,
> +		.cross_timestamping	= ptp->info->getcrosststamp != NULL,
> +		.adjust_phase		= ptp->info->adjphase != NULL &&
> +					  ptp->info->getmaxphase != NULL,
> +	};
> +
> +	if (caps.adjust_phase)
> +		caps.max_phase_adj = ptp->info->getmaxphase(ptp->info);
> +
> +	return copy_to_user(arg, &caps, sizeof(caps)) ? -EFAULT : 0;
> +}
> +
>   long ptp_ioctl(struct posix_clock_context *pccontext, unsigned int cmd,
>   	       unsigned long arg)
>   {
> @@ -171,37 +191,22 @@ long ptp_ioctl(struct posix_clock_contex
>   	struct timestamp_event_queue *tsevq;
>   	struct ptp_system_timestamp sts;
>   	struct ptp_clock_request req;
> -	struct ptp_clock_caps caps;
>   	struct ptp_clock_time *pct;
>   	struct ptp_pin_desc pd;
>   	struct timespec64 ts;
>   	int enable, err = 0;
> +	void __user *argptr;
>   
>   	if (in_compat_syscall() && cmd != PTP_ENABLE_PPS && cmd != PTP_ENABLE_PPS2)
>   		arg = (unsigned long)compat_ptr(arg);
> +	argptr = (void __force __user *)arg;
>   
>   	tsevq = pccontext->private_clkdata;
>   
>   	switch (cmd) {
> -
>   	case PTP_CLOCK_GETCAPS:
>   	case PTP_CLOCK_GETCAPS2:
> -		memset(&caps, 0, sizeof(caps));
> -
> -		caps.max_adj = ptp->info->max_adj;
> -		caps.n_alarm = ptp->info->n_alarm;
> -		caps.n_ext_ts = ptp->info->n_ext_ts;
> -		caps.n_per_out = ptp->info->n_per_out;
> -		caps.pps = ptp->info->pps;
> -		caps.n_pins = ptp->info->n_pins;
> -		caps.cross_timestamping = ptp->info->getcrosststamp != NULL;
> -		caps.adjust_phase = ptp->info->adjphase != NULL &&
> -				    ptp->info->getmaxphase != NULL;
> -		if (caps.adjust_phase)
> -			caps.max_phase_adj = ptp->info->getmaxphase(ptp->info);
> -		if (copy_to_user((void __user *)arg, &caps, sizeof(caps)))
> -			err = -EFAULT;
> -		break;
> +		return ptp_clock_getcaps(ptp, argptr);
>   
>   	case PTP_EXTTS_REQUEST:
>   	case PTP_EXTTS_REQUEST2:
> 
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@...ux.dev>