linux-kernel - Re: [patch 2/6] timekeeping: Make the conversion call chain consistently unsigned

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Message-ID: <20161208233922.GK13139@umbus.fritz.box>
Date:   Fri, 9 Dec 2016 10:39:22 +1100
From:   David Gibson <david@...son.dropbear.id.au>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        John Stultz <john.stultz@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Liav Rehana <liavr@...lanox.com>,
        Chris Metcalf <cmetcalf@...lanox.com>,
        Richard Cochran <richardcochran@...il.com>,
        Parit Bhargava <prarit@...hat.com>,
        Laurent Vivier <lvivier@...hat.com>,
        "Christopher S. Hall" <christopher.s.hall@...el.com>
Subject: Re: [patch 2/6] timekeeping: Make the conversion call chain
 consistently unsigned

On Thu, Dec 08, 2016 at 08:49:34PM -0000, Thomas Gleixner wrote:
> Propagating a unsigned value through signed variables and functions makes
> absolutely no sense and is just prone to (re)introduce subtle signed
> vs. unsigned issues as happened recently.
> 
> Clean it up.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

Reviewed-by: David Gibson <david@...son.dropbear.id.au>

> ---
>  kernel/time/timekeeping.c |   26 +++++++++++++-------------
>  1 file changed, 13 insertions(+), 13 deletions(-)
> 
> --- a/kernel/time/timekeeping.c
> +++ b/kernel/time/timekeeping.c
> @@ -311,7 +311,7 @@ static inline u64 timekeeping_delta_to_n
>  	return nsec + arch_gettimeoffset();
>  }
>  
> -static inline s64 timekeeping_get_ns(struct tk_read_base *tkr)
> +static inline u64 timekeeping_get_ns(struct tk_read_base *tkr)
>  {
>  	cycle_t delta;
>  
> @@ -319,8 +319,8 @@ static inline s64 timekeeping_get_ns(str
>  	return timekeeping_delta_to_ns(tkr, delta);
>  }
>  
> -static inline s64 timekeeping_cycles_to_ns(struct tk_read_base *tkr,
> -					    cycle_t cycles)
> +static inline u64 timekeeping_cycles_to_ns(struct tk_read_base *tkr,
> +					   cycle_t cycles)
>  {
>  	cycle_t delta;
>  
> @@ -623,7 +623,7 @@ static void timekeeping_forward_now(stru
>  {
>  	struct clocksource *clock = tk->tkr_mono.clock;
>  	cycle_t cycle_now, delta;
> -	s64 nsec;
> +	u64 nsec;
>  
>  	cycle_now = tk->tkr_mono.read(clock);
>  	delta = clocksource_delta(cycle_now, tk->tkr_mono.cycle_last, tk->tkr_mono.mask);
> @@ -652,7 +652,7 @@ int __getnstimeofday64(struct timespec64
>  {
>  	struct timekeeper *tk = &tk_core.timekeeper;
>  	unsigned long seq;
> -	s64 nsecs = 0;
> +	u64 nsecs;
>  
>  	do {
>  		seq = read_seqcount_begin(&tk_core.seq);
> @@ -692,7 +692,7 @@ ktime_t ktime_get(void)
>  	struct timekeeper *tk = &tk_core.timekeeper;
>  	unsigned int seq;
>  	ktime_t base;
> -	s64 nsecs;
> +	u64 nsecs;
>  
>  	WARN_ON(timekeeping_suspended);
>  
> @@ -735,7 +735,7 @@ ktime_t ktime_get_with_offset(enum tk_of
>  	struct timekeeper *tk = &tk_core.timekeeper;
>  	unsigned int seq;
>  	ktime_t base, *offset = offsets[offs];
> -	s64 nsecs;
> +	u64 nsecs;
>  
>  	WARN_ON(timekeeping_suspended);
>  
> @@ -779,7 +779,7 @@ ktime_t ktime_get_raw(void)
>  	struct timekeeper *tk = &tk_core.timekeeper;
>  	unsigned int seq;
>  	ktime_t base;
> -	s64 nsecs;
> +	u64 nsecs;
>  
>  	do {
>  		seq = read_seqcount_begin(&tk_core.seq);
> @@ -804,8 +804,8 @@ void ktime_get_ts64(struct timespec64 *t
>  {
>  	struct timekeeper *tk = &tk_core.timekeeper;
>  	struct timespec64 tomono;
> -	s64 nsec;
>  	unsigned int seq;
> +	u64 nsec;
>  
>  	WARN_ON(timekeeping_suspended);
>  
> @@ -893,8 +893,8 @@ void ktime_get_snapshot(struct system_ti
>  	unsigned long seq;
>  	ktime_t base_raw;
>  	ktime_t base_real;
> -	s64 nsec_raw;
> -	s64 nsec_real;
> +	u64 nsec_raw;
> +	u64 nsec_real;
>  	cycle_t now;
>  
>  	WARN_ON_ONCE(timekeeping_suspended);
> @@ -1052,7 +1052,7 @@ int get_device_system_crosststamp(int (*
>  	cycle_t cycles, now, interval_start;
>  	unsigned int clock_was_set_seq = 0;
>  	ktime_t base_real, base_raw;
> -	s64 nsec_real, nsec_raw;
> +	u64 nsec_real, nsec_raw;
>  	u8 cs_was_changed_seq;
>  	unsigned long seq;
>  	bool do_interp;
> @@ -1365,7 +1365,7 @@ void getrawmonotonic64(struct timespec64
>  	struct timekeeper *tk = &tk_core.timekeeper;
>  	struct timespec64 ts64;
>  	unsigned long seq;
> -	s64 nsecs;
> +	u64 nsecs;
>  
>  	do {
>  		seq = read_seqcount_begin(&tk_core.seq);
> 
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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