The original msecs_to_jiffies is renamed to __msecs_to_jiffies and aside from the removal of the check for negative values being moved out, is unaltered.
Signed-off-by: Nicholas Mc Guire <[email protected]> --- Thanks to Joe Perches <[email protected]> for suggesting this approach and for his review comments on the first attempts and for the simple test-case that helped after I confused my self with .lst files. V2: remove duplicated code by moving it to helper functions reformatted the #ifdef to a hopefully more readable code in include/linux/jiffies.h and simplified __msecs_to_jiffies() by re-using the helpers. Question: * nameing conventions _msecs_to_jiffies() suitable as helper name ? * the suitability of the #ifdef/#elif/#else construct Patch was compile and boot tested (x86_64) and a few msecs_to_jiffies() locations verified by inspection of the .s files where constants are reduced to a load or add instruction and the non-const. call __msecs_to_jiffies(). Patch is against 4.0-rc7 (localversion-next is -next-20150410) include/linux/jiffies.h | 35 ++++++++++++++++++++++++++++++++++- kernel/time/time.c | 40 ++++++---------------------------------- 2 files changed, 40 insertions(+), 35 deletions(-) diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h index c367cbd..273b093 100644 --- a/include/linux/jiffies.h +++ b/include/linux/jiffies.h @@ -7,6 +7,7 @@ #include <linux/time.h> #include <linux/timex.h> #include <asm/param.h> /* for HZ */ +#include <generated/timeconst.h> /* * The following defines establish the engineering parameters of the PLL @@ -288,7 +289,39 @@ static inline u64 jiffies_to_nsecs(const unsigned long j) 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) +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) +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 +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 +static inline unsigned long msecs_to_jiffies(const unsigned int m) +{ + if (__builtin_constant_p(m)) { + if ((int)m < 0) + return MAX_JIFFY_OFFSET; + return _msecs_to_jiffies(m); + } else + return __msecs_to_jiffies(m); +} + extern unsigned long usecs_to_jiffies(const unsigned int u); extern unsigned long timespec_to_jiffies(const struct timespec *value); extern void jiffies_to_timespec(const unsigned long jiffies, diff --git a/kernel/time/time.c b/kernel/time/time.c index 4fa1d26..25bee56 100644 --- a/kernel/time/time.c +++ b/kernel/time/time.c @@ -488,6 +488,8 @@ EXPORT_SYMBOL(ns_to_timespec64); * the following way: * * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET) + * negative values are handled in msecs_to_jiffies in + * include/linux/jiffies.h * * - 'too large' values [that would result in larger than * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too. @@ -496,48 +498,18 @@ EXPORT_SYMBOL(ns_to_timespec64); * the input value by a factor or dividing it with a factor * * We must also be careful about 32-bit overflows. + * */ -unsigned long msecs_to_jiffies(const unsigned int m) +unsigned long __msecs_to_jiffies(const unsigned int m) { /* * Negative value, means infinite timeout: */ if ((int)m < 0) return MAX_JIFFY_OFFSET; - -#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 + return _msecs_to_jiffies(m); } -EXPORT_SYMBOL(msecs_to_jiffies); +EXPORT_SYMBOL(__msecs_to_jiffies); unsigned long usecs_to_jiffies(const unsigned int u) { -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
