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

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Date:   Mon, 24 Feb 2020 15:23:43 -0800
From:   "Christopher S. Hall" <christopher.s.hall@...el.com>
To:     Richard Cochran <richardcochran@...il.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

Hi Richard,

Thanks for the detailed review.

On Sun, Feb 02, 2020 at 05:27:00PM -0800, Richard Cochran wrote:
> 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.

OK. Done.

> >  #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?

No problem. Sounds good.

> > +{
> > +	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++

OK for both of these.

> > +
> > +	return ret;
> > +}
> > +#define check_rsv_field(field) _check_rsv_field(field, ARRAY_SIZE(field))
> 
> And check_reserved_field() here.  No need to abbreviate.

OK. Done.

> Thanks,
> Richard

Thanks,
Chris