linux-kernel - Re: [Intel PMC TGPIO Driver 1/5] drivers/ptp: Add Enhanced handling of reserve fields

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Message-ID: <20200203012700.GA2354@localhost>
Date:   Sun, 2 Feb 2020 17:27:00 -0800
From:   Richard Cochran <richardcochran@...il.com>
To:     christopher.s.hall@...el.com
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, hpa@...or.com, mingo@...hat.com,
        x86@...nel.org, jacob.e.keller@...el.com, davem@...emloft.net,
        sean.v.kelley@...el.com
Subject: Re: [Intel PMC TGPIO Driver 1/5] drivers/ptp: Add Enhanced handling
 of reserve fields

On Wed, Dec 11, 2019 at 01:48:48PM -0800, christopher.s.hall@...el.com wrote:
> diff --git a/drivers/ptp/ptp_chardev.c b/drivers/ptp/ptp_chardev.c
> index 9d72ab593f13..f9ad6df57fa5 100644
> --- a/drivers/ptp/ptp_chardev.c
> +++ b/drivers/ptp/ptp_chardev.c
> @@ -12,6 +12,7 @@
>  #include <linux/timekeeping.h>
>  
>  #include <linux/nospec.h>
> +#include <linux/string.h>

Please group these two includes with the others, above, in
alphabetical order.

>  #include "ptp_private.h"
>  
> @@ -106,6 +107,28 @@ int ptp_open(struct posix_clock *pc, fmode_t fmode)
>  	return 0;
>  }
>  
> +/* Returns -1 if any reserved fields are non-zero */
> +static inline int _check_rsv_field(unsigned int *field, size_t size)

How about _check_reserved_field() instead?

> +{
> +	unsigned int *iter;

Ugh, 'ptr' please.

> +	int ret = 0;
> +
> +	for (iter = field; iter < field+size && ret == 0; ++iter)
> +		ret = *iter == 0 ? 0 : -1;

Please use the "early out" pattern:

	for (ptr = field; ptr < field + size; ptr++) {
		if (*ptr) {
			return -1;
		}
	}
	return 0;

Note:  field + size
Note:  ptr++

> +
> +	return ret;
> +}
> +#define check_rsv_field(field) _check_rsv_field(field, ARRAY_SIZE(field))

And check_reserved_field() here.  No need to abbreviate.

Thanks,
Richard