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Commit ca42aaf0 authored by Nicholas Mc Guire's avatar Nicholas Mc Guire Committed by Thomas Gleixner
Browse files

time: Refactor msecs_to_jiffies 



Refactor the msecs_to_jiffies conditional code part in time.c and 
jiffies.h putting it into conditional functions rather than #ifdefs
to improve readability.

[ tglx: Verified that there is no binary code change ]

Signed-off-by: default avatarNicholas Mc Guire <hofrat@osadl.org>
Cc: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Joe Perches <joe@perches.com>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Andrew Hunter <ahh@google.com>
Cc: Paul Turner <pjt@google.com>
Cc: Michal Marek <mmarek@suse.cz>
Link: http://lkml.kernel.org/r/1431951554-5563-2-git-send-email-hofrat@osadl.org


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 0a227985

include/linux/jiffies.h

+63 −1
Original line number Original line Diff line number Diff line
@@ -7,6 +7,7 @@ 
#include <linux/time.h>

#include <linux/time.h>

#include <linux/timex.h>

#include <linux/timex.h>

#include <asm/param.h>			/* for HZ */

#include <asm/param.h>			/* for HZ */

#include <generated/timeconst.h>





/*

/*

 * The following defines establish the engineering parameters of the PLL

 * The following defines establish the engineering parameters of the PLL
@@ -288,7 +289,68 @@ static inline u64 jiffies_to_nsecs(const unsigned long j) 
	return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC;

	return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC;

}

}





extern unsigned long msecs_to_jiffies(const unsigned int m);

extern unsigned long __msecs_to_jiffies(const unsigned int m);

#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)

/*

 * HZ is equal to or smaller than 1000, and 1000 is a nice round

 * multiple of HZ, divide with the factor between them, but round

 * upwards:

 */

static inline unsigned long _msecs_to_jiffies(const unsigned int m)

{

		return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);

}

#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)

/*

 * HZ is larger than 1000, and HZ is a nice round multiple of 1000 -

 * simply multiply with the factor between them.

 *

 * But first make sure the multiplication result cannot overflow:

 */

static inline unsigned long _msecs_to_jiffies(const unsigned int m)

{

		if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))

			return MAX_JIFFY_OFFSET;

		return m * (HZ / MSEC_PER_SEC);

}

#else

/*

 * Generic case - multiply, round and divide. But first check that if

 * we are doing a net multiplication, that we wouldn't overflow:

 */

static inline unsigned long _msecs_to_jiffies(const unsigned int m)

{

		if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))

			return MAX_JIFFY_OFFSET;



		return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32)

			>> MSEC_TO_HZ_SHR32;

}

#endif

/**

 * msecs_to_jiffies: - convert milliseconds to jiffies

 * @m:	time in milliseconds

 *

 * conversion is done as follows:

 *

 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)

 *

 * - 'too large' values [that would result in larger than

 *   MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.

 *

 * - all other values are converted to jiffies by either multiplying

 *   the input value by a factor or dividing it with a factor and

 *   handling any 32-bit overflows.

 *   for the details see __msecs_to_jiffies()

 *

 * the HZ range specific helpers _msecs_to_jiffies() are called from

 * __msecs_to_jiffies().

 */

static inline unsigned long msecs_to_jiffies(const unsigned int m)

{

	return __msecs_to_jiffies(m);

}



extern unsigned long usecs_to_jiffies(const unsigned int u);

extern unsigned long usecs_to_jiffies(const unsigned int u);

extern unsigned long timespec_to_jiffies(const struct timespec *value);

extern unsigned long timespec_to_jiffies(const struct timespec *value);

extern void jiffies_to_timespec(const unsigned long jiffies,

extern void jiffies_to_timespec(const unsigned long jiffies,

kernel/time/time.c

+19 −40
Original line number Original line Diff line number Diff line
@@ -483,9 +483,11 @@ struct timespec64 ns_to_timespec64(const s64 nsec) 
}

}

EXPORT_SYMBOL(ns_to_timespec64);

EXPORT_SYMBOL(ns_to_timespec64);

#endif

#endif

/*

/**

 * When we convert to jiffies then we interpret incoming values

 * msecs_to_jiffies: - convert milliseconds to jiffies

 * the following way:

 * @m:	time in milliseconds

 *

 * conversion is done as follows:

 *

 *

 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)

 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)

 *

 *
@@ -493,51 +495,28 @@ EXPORT_SYMBOL(ns_to_timespec64); 
 *   MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.

 *   MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.

 *

 *

 * - all other values are converted to jiffies by either multiplying

 * - all other values are converted to jiffies by either multiplying

 *   the input value by a factor or dividing it with a factor

 *   the input value by a factor or dividing it with a factor and

 *

 *   handling any 32-bit overflows.

 * We must also be careful about 32-bit overflows.

 *   for the details see __msecs_to_jiffies()

 */

 *

unsigned long msecs_to_jiffies(const unsigned int m)

 * msecs_to_jiffies() checks for the passed in value being a constant

 * via __builtin_constant_p() allowing gcc to eliminate most of the

 * code, __msecs_to_jiffies() is called if the value passed does not

 * allow constant folding and the actual conversion must be done at

 * runtime.

 * the _msecs_to_jiffies helpers are the HZ dependent conversion

 * routines found in include/linux/jiffies.h

 */

unsigned long __msecs_to_jiffies(const unsigned int m)

{

{

	/*

	/*

	 * Negative value, means infinite timeout:

	 * Negative value, means infinite timeout:

	 */

	 */

	if ((int)m < 0)

	if ((int)m < 0)

		return MAX_JIFFY_OFFSET;

		return MAX_JIFFY_OFFSET;



	return _msecs_to_jiffies(m);

#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)

	/*

	 * HZ is equal to or smaller than 1000, and 1000 is a nice

	 * round multiple of HZ, divide with the factor between them,

	 * but round upwards:

	 */

	return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);

#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)

	/*

	 * HZ is larger than 1000, and HZ is a nice round multiple of

	 * 1000 - simply multiply with the factor between them.

	 *

	 * But first make sure the multiplication result cannot

	 * overflow:

	 */

	if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))

		return MAX_JIFFY_OFFSET;



	return m * (HZ / MSEC_PER_SEC);

#else

	/*

	 * Generic case - multiply, round and divide. But first

	 * check that if we are doing a net multiplication, that

	 * we wouldn't overflow:

	 */

	if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))

		return MAX_JIFFY_OFFSET;



	return (MSEC_TO_HZ_MUL32 * m + MSEC_TO_HZ_ADJ32)

		>> MSEC_TO_HZ_SHR32;

#endif

}

}

EXPORT_SYMBOL(msecs_to_jiffies);

EXPORT_SYMBOL(__msecs_to_jiffies);





unsigned long usecs_to_jiffies(const unsigned int u)

unsigned long usecs_to_jiffies(const unsigned int u)

{

{