Re: [RFC/PATCH 4/5] cputime: use do_div() for nsec resolution conversion helpers

From: Namhyung Kim <namhyung@kernel.org>
To: Kevin Hilman <khilman@linaro.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
	Mats Liljegren <mats.liljegren@enea.com>,
	linaro-dev@lists.linaro.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC/PATCH 4/5] cputime: use do_div() for nsec resolution conversion helpers
Date: Thu, 21 Feb 2013 09:58:57 -0800	[thread overview]
Message-ID: <20130221175857.GB14256@danjae.linux.parc55> (raw)
In-Reply-To: <1361389302-11968-5-git-send-email-khilman@linaro.org>

Hi Kevin,

On Wed, Feb 20, 2013 at 11:41:41AM -0800, Kevin Hilman wrote:
> For the nsec resolution conversions to be useful on non 64-bit
> architectures, do_div() needs to be used for the 64-bit divisions.
> 
> Signed-off-by: Kevin Hilman <khilman@linaro.org>
> ---
>  include/asm-generic/cputime_nsecs.h | 51 +++++++++++++++++++++++++++----------
>  1 file changed, 37 insertions(+), 14 deletions(-)
> 
> diff --git a/include/asm-generic/cputime_nsecs.h b/include/asm-generic/cputime_nsecs.h
> index b6485ca..daa6075 100644
> --- a/include/asm-generic/cputime_nsecs.h
> +++ b/include/asm-generic/cputime_nsecs.h
> @@ -24,13 +24,17 @@ typedef u64 __nocast cputime64_t;
>  /*
>   * Convert cputime <-> jiffies (HZ)
>   */
> -#define cputime_to_jiffies(__ct)	\
> -	((__force u64)(__ct) / (NSEC_PER_SEC / HZ))
> +static inline u64 cputime_to_jiffies(const cputime_t ct)
> +{
> +	cputime_t __ct = ct;

Why it removed the "(__force u64)" conversion part?  Shouldn't it be:

	u64 __ct = (__force u64) ct;

?  (and ditto for below changes)

Thanks,
Namhyung

> +
> +	do_div(__ct, NSEC_PER_SEC / HZ);
> +	return __ct;
> +}
>  #define cputime_to_scaled(__ct)		(__ct)
>  #define jiffies_to_cputime(__jif)	\
>  	(__force cputime_t)((__jif) * (NSEC_PER_SEC / HZ))
> -#define cputime64_to_jiffies64(__ct)	\
> -	((__force u64)(__ct) / (NSEC_PER_SEC / HZ))
> +#define cputime64_to_jiffies64(__ct) cputime_to_jiffies(__ct)
>  #define jiffies64_to_cputime64(__jif)	\
>  	(__force cputime64_t)((__jif) * (NSEC_PER_SEC / HZ))
>  
> @@ -44,8 +48,13 @@ typedef u64 __nocast cputime64_t;
>  /*
>   * Convert cputime <-> microseconds
>   */
> -#define cputime_to_usecs(__ct)		\
> -	((__force u64)(__ct) / NSEC_PER_USEC)
> +static inline u64 cputime_to_usecs(const cputime_t ct)
> +{
> +	cputime_t __ct = ct;
> +
> +	do_div(__ct, NSEC_PER_USEC);
> +	return __ct;
> +}
>  #define usecs_to_cputime(__usecs)	\
>  	(__force cputime_t)((__usecs) * NSEC_PER_USEC)
>  #define usecs_to_cputime64(__usecs)	\
> @@ -54,8 +63,13 @@ typedef u64 __nocast cputime64_t;
>  /*
>   * Convert cputime <-> seconds
>   */
> -#define cputime_to_secs(__ct)		\
> -	((__force u64)(__ct) / NSEC_PER_SEC)
> +static inline u64 cputime_to_secs(const cputime_t ct)
> +{
> +	cputime_t __ct = ct;
> +
> +	do_div(__ct, NSEC_PER_SEC);
> +	return __ct;
> +}
>  #define secs_to_cputime(__secs)		\
>  	(__force cputime_t)((__secs) * NSEC_PER_SEC)
>  
> @@ -69,8 +83,10 @@ static inline cputime_t timespec_to_cputime(const struct timespec *val)
>  }
>  static inline void cputime_to_timespec(const cputime_t ct, struct timespec *val)
>  {
> -	val->tv_sec  = (__force u64) ct / NSEC_PER_SEC;
> -	val->tv_nsec = (__force u64) ct % NSEC_PER_SEC;
> +	cputime_t __ct = ct;
> +
> +	val->tv_nsec = do_div(__ct, NSEC_PER_SEC);
> +	val->tv_sec = __ct;
>  }
>  
>  /*
> @@ -83,15 +99,22 @@ static inline cputime_t timeval_to_cputime(struct timeval *val)
>  }
>  static inline void cputime_to_timeval(const cputime_t ct, struct timeval *val)
>  {
> -	val->tv_sec = (__force u64) ct / NSEC_PER_SEC;
> -	val->tv_usec = ((__force u64) ct % NSEC_PER_SEC) / NSEC_PER_USEC;
> +	cputime_t __ct = ct;
> +
> +	val->tv_usec = do_div(__ct, NSEC_PER_SEC) / NSEC_PER_USEC;
> +	val->tv_sec = __ct;
>  }
>  
>  /*
>   * Convert cputime <-> clock (USER_HZ)
>   */
> -#define cputime_to_clock_t(__ct)	\
> -	((__force u64)(__ct) / (NSEC_PER_SEC / USER_HZ))
> +static inline u64 cputime_to_clock_t(const cputime_t ct)
> +{
> +	cputime_t __ct = ct;
> +
> +	do_div(__ct, (NSEC_PER_SEC / USER_HZ));
> +	return __ct;
> +}
>  #define clock_t_to_cputime(__x)		\
>  	(__force cputime_t)((__x) * (NSEC_PER_SEC / USER_HZ))
>  
> -- 
> 1.8.1.2
> 
> 
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