diff options
| -rw-r--r-- | include/linux/jiffies.h | 64 | ||||
| -rw-r--r-- | kernel/time/time.c | 59 |
2 files changed, 82 insertions, 41 deletions
diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h index c367cbdf73ab..9527ddbb0f1b 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 +289,68 @@ 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) +/* + * 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 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 4fa1d26a9843..c42c2c3214fe 100644 --- a/kernel/time/time.c +++ b/kernel/time/time.c @@ -483,9 +483,11 @@ struct timespec64 ns_to_timespec64(const s64 nsec) } EXPORT_SYMBOL(ns_to_timespec64); #endif -/* - * When we convert to jiffies then we interpret incoming values - * the following way: +/** + * msecs_to_jiffies: - convert milliseconds to jiffies + * @m: time in milliseconds + * + * conversion is done as follows: * * - 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. * * - all other values are converted to jiffies by either multiplying - * the input value by a factor or dividing it with a factor - * - * We must also be careful about 32-bit overflows. + * 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() + * + * 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) +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) { |