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time: add kernel-doc in time.c
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Add kernel-doc for all APIs that do not already have it.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: John Stultz <jstultz@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Acked-by: John Stultz <jstultz@google.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230704052405.5089-3-rdunlap@infradead.org
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Randy Dunlap authored and Jonathan Corbet committed Jul 14, 2023
1 parent 6d07a31 commit 67b3f56
Showing 1 changed file with 158 additions and 11 deletions.
169 changes: 158 additions & 11 deletions kernel/time/time.c
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Original file line number Diff line number Diff line change
Expand Up @@ -365,11 +365,14 @@ SYSCALL_DEFINE1(adjtimex_time32, struct old_timex32 __user *, utp)
}
#endif

/*
* Convert jiffies to milliseconds and back.
/**
* jiffies_to_msecs - Convert jiffies to milliseconds
* @j: jiffies value
*
* Avoid unnecessary multiplications/divisions in the
* two most common HZ cases:
* two most common HZ cases.
*
* Return: milliseconds value
*/
unsigned int jiffies_to_msecs(const unsigned long j)
{
Expand All @@ -388,6 +391,12 @@ unsigned int jiffies_to_msecs(const unsigned long j)
}
EXPORT_SYMBOL(jiffies_to_msecs);

/**
* jiffies_to_usecs - Convert jiffies to microseconds
* @j: jiffies value
*
* Return: microseconds value
*/
unsigned int jiffies_to_usecs(const unsigned long j)
{
/*
Expand All @@ -408,8 +417,15 @@ unsigned int jiffies_to_usecs(const unsigned long j)
}
EXPORT_SYMBOL(jiffies_to_usecs);

/*
/**
* mktime64 - Converts date to seconds.
* @year0: year to convert
* @mon0: month to convert
* @day: day to convert
* @hour: hour to convert
* @min: minute to convert
* @sec: second to convert
*
* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
* Assumes input in normal date format, i.e. 1980-12-31 23:59:59
* => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
Expand All @@ -427,6 +443,8 @@ EXPORT_SYMBOL(jiffies_to_usecs);
*
* An encoding of midnight at the end of the day as 24:00:00 - ie. midnight
* tomorrow - (allowable under ISO 8601) is supported.
*
* Return: seconds since the epoch time for the given input date
*/
time64_t mktime64(const unsigned int year0, const unsigned int mon0,
const unsigned int day, const unsigned int hour,
Expand Down Expand Up @@ -471,8 +489,7 @@ EXPORT_SYMBOL(ns_to_kernel_old_timeval);
* Set seconds and nanoseconds field of a timespec variable and
* normalize to the timespec storage format
*
* Note: The tv_nsec part is always in the range of
* 0 <= tv_nsec < NSEC_PER_SEC
* Note: The tv_nsec part is always in the range of 0 <= tv_nsec < NSEC_PER_SEC.
* For negative values only the tv_sec field is negative !
*/
void set_normalized_timespec64(struct timespec64 *ts, time64_t sec, s64 nsec)
Expand Down Expand Up @@ -501,7 +518,7 @@ EXPORT_SYMBOL(set_normalized_timespec64);
* ns_to_timespec64 - Convert nanoseconds to timespec64
* @nsec: the nanoseconds value to be converted
*
* Returns the timespec64 representation of the nsec parameter.
* Return: the timespec64 representation of the nsec parameter.
*/
struct timespec64 ns_to_timespec64(s64 nsec)
{
Expand Down Expand Up @@ -548,6 +565,8 @@ EXPORT_SYMBOL(ns_to_timespec64);
* runtime.
* The _msecs_to_jiffies helpers are the HZ dependent conversion
* routines found in include/linux/jiffies.h
*
* Return: jiffies value
*/
unsigned long __msecs_to_jiffies(const unsigned int m)
{
Expand All @@ -560,6 +579,12 @@ unsigned long __msecs_to_jiffies(const unsigned int m)
}
EXPORT_SYMBOL(__msecs_to_jiffies);

/**
* __usecs_to_jiffies: - convert microseconds to jiffies
* @u: time in milliseconds
*
* Return: jiffies value
*/
unsigned long __usecs_to_jiffies(const unsigned int u)
{
if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
Expand All @@ -568,7 +593,10 @@ unsigned long __usecs_to_jiffies(const unsigned int u)
}
EXPORT_SYMBOL(__usecs_to_jiffies);

/*
/**
* timespec64_to_jiffies - convert a timespec64 value to jiffies
* @value: pointer to &struct timespec64
*
* The TICK_NSEC - 1 rounds up the value to the next resolution. Note
* that a remainder subtract here would not do the right thing as the
* resolution values don't fall on second boundaries. I.e. the line:
Expand All @@ -582,8 +610,9 @@ EXPORT_SYMBOL(__usecs_to_jiffies);
*
* The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec
* value to a scaled second value.
*
* Return: jiffies value
*/

unsigned long
timespec64_to_jiffies(const struct timespec64 *value)
{
Expand All @@ -601,6 +630,11 @@ timespec64_to_jiffies(const struct timespec64 *value)
}
EXPORT_SYMBOL(timespec64_to_jiffies);

/**
* jiffies_to_timespec64 - convert jiffies value to &struct timespec64
* @jiffies: jiffies value
* @value: pointer to &struct timespec64
*/
void
jiffies_to_timespec64(const unsigned long jiffies, struct timespec64 *value)
{
Expand All @@ -618,6 +652,13 @@ EXPORT_SYMBOL(jiffies_to_timespec64);
/*
* Convert jiffies/jiffies_64 to clock_t and back.
*/

/**
* jiffies_to_clock_t - Convert jiffies to clock_t
* @x: jiffies value
*
* Return: jiffies converted to clock_t (CLOCKS_PER_SEC)
*/
clock_t jiffies_to_clock_t(unsigned long x)
{
#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
Expand All @@ -632,6 +673,12 @@ clock_t jiffies_to_clock_t(unsigned long x)
}
EXPORT_SYMBOL(jiffies_to_clock_t);

/**
* clock_t_to_jiffies - Convert clock_t to jiffies
* @x: clock_t value
*
* Return: clock_t value converted to jiffies
*/
unsigned long clock_t_to_jiffies(unsigned long x)
{
#if (HZ % USER_HZ)==0
Expand All @@ -649,6 +696,12 @@ unsigned long clock_t_to_jiffies(unsigned long x)
}
EXPORT_SYMBOL(clock_t_to_jiffies);

/**
* jiffies_64_to_clock_t - Convert jiffies_64 to clock_t
* @x: jiffies_64 value
*
* Return: jiffies_64 value converted to 64-bit "clock_t" (CLOCKS_PER_SEC)
*/
u64 jiffies_64_to_clock_t(u64 x)
{
#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
Expand All @@ -671,6 +724,12 @@ u64 jiffies_64_to_clock_t(u64 x)
}
EXPORT_SYMBOL(jiffies_64_to_clock_t);

/**
* nsec_to_clock_t - Convert nsec value to clock_t
* @x: nsec value
*
* Return: nsec value converted to 64-bit "clock_t" (CLOCKS_PER_SEC)
*/
u64 nsec_to_clock_t(u64 x)
{
#if (NSEC_PER_SEC % USER_HZ) == 0
Expand All @@ -687,6 +746,12 @@ u64 nsec_to_clock_t(u64 x)
#endif
}

/**
* jiffies64_to_nsecs - Convert jiffies64 to nanoseconds
* @j: jiffies64 value
*
* Return: nanoseconds value
*/
u64 jiffies64_to_nsecs(u64 j)
{
#if !(NSEC_PER_SEC % HZ)
Expand All @@ -697,6 +762,12 @@ u64 jiffies64_to_nsecs(u64 j)
}
EXPORT_SYMBOL(jiffies64_to_nsecs);

/**
* jiffies64_to_msecs - Convert jiffies64 to milliseconds
* @j: jiffies64 value
*
* Return: milliseconds value
*/
u64 jiffies64_to_msecs(const u64 j)
{
#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
Expand All @@ -719,6 +790,8 @@ EXPORT_SYMBOL(jiffies64_to_msecs);
* note:
* NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
* ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
*
* Return: nsecs converted to jiffies64 value
*/
u64 nsecs_to_jiffies64(u64 n)
{
Expand Down Expand Up @@ -750,17 +823,25 @@ EXPORT_SYMBOL(nsecs_to_jiffies64);
* note:
* NSEC_PER_SEC = 10^9 = (5^9 * 2^9) = (1953125 * 512)
* ULLONG_MAX ns = 18446744073.709551615 secs = about 584 years
*
* Return: nsecs converted to jiffies value
*/
unsigned long nsecs_to_jiffies(u64 n)
{
return (unsigned long)nsecs_to_jiffies64(n);
}
EXPORT_SYMBOL_GPL(nsecs_to_jiffies);

/*
* Add two timespec64 values and do a safety check for overflow.
/**
* timespec64_add_safe - Add two timespec64 values and do a safety check
* for overflow.
* @lhs: first (left) timespec64 to add
* @rhs: second (right) timespec64 to add
*
* It's assumed that both values are valid (>= 0).
* And, each timespec64 is in normalized form.
*
* Return: sum of @lhs + @rhs
*/
struct timespec64 timespec64_add_safe(const struct timespec64 lhs,
const struct timespec64 rhs)
Expand All @@ -778,6 +859,15 @@ struct timespec64 timespec64_add_safe(const struct timespec64 lhs,
return res;
}

/**
* get_timespec64 - get user's time value into kernel space
* @ts: destination &struct timespec64
* @uts: user's time value as &struct __kernel_timespec
*
* Handles compat or 32-bit modes.
*
* Return: %0 on success or negative errno on error
*/
int get_timespec64(struct timespec64 *ts,
const struct __kernel_timespec __user *uts)
{
Expand All @@ -801,6 +891,14 @@ int get_timespec64(struct timespec64 *ts,
}
EXPORT_SYMBOL_GPL(get_timespec64);

/**
* put_timespec64 - convert timespec64 value to __kernel_timespec format and
* copy the latter to userspace
* @ts: input &struct timespec64
* @uts: user's &struct __kernel_timespec
*
* Return: %0 on success or negative errno on error
*/
int put_timespec64(const struct timespec64 *ts,
struct __kernel_timespec __user *uts)
{
Expand Down Expand Up @@ -839,6 +937,15 @@ static int __put_old_timespec32(const struct timespec64 *ts64,
return copy_to_user(cts, &ts, sizeof(ts)) ? -EFAULT : 0;
}

/**
* get_old_timespec32 - get user's old-format time value into kernel space
* @ts: destination &struct timespec64
* @uts: user's old-format time value (&struct old_timespec32)
*
* Handles X86_X32_ABI compatibility conversion.
*
* Return: %0 on success or negative errno on error
*/
int get_old_timespec32(struct timespec64 *ts, const void __user *uts)
{
if (COMPAT_USE_64BIT_TIME)
Expand All @@ -848,6 +955,16 @@ int get_old_timespec32(struct timespec64 *ts, const void __user *uts)
}
EXPORT_SYMBOL_GPL(get_old_timespec32);

/**
* put_old_timespec32 - convert timespec64 value to &struct old_timespec32 and
* copy the latter to userspace
* @ts: input &struct timespec64
* @uts: user's &struct old_timespec32
*
* Handles X86_X32_ABI compatibility conversion.
*
* Return: %0 on success or negative errno on error
*/
int put_old_timespec32(const struct timespec64 *ts, void __user *uts)
{
if (COMPAT_USE_64BIT_TIME)
Expand All @@ -857,6 +974,13 @@ int put_old_timespec32(const struct timespec64 *ts, void __user *uts)
}
EXPORT_SYMBOL_GPL(put_old_timespec32);

/**
* get_itimerspec64 - get user's &struct __kernel_itimerspec into kernel space
* @it: destination &struct itimerspec64
* @uit: user's &struct __kernel_itimerspec
*
* Return: %0 on success or negative errno on error
*/
int get_itimerspec64(struct itimerspec64 *it,
const struct __kernel_itimerspec __user *uit)
{
Expand All @@ -872,6 +996,14 @@ int get_itimerspec64(struct itimerspec64 *it,
}
EXPORT_SYMBOL_GPL(get_itimerspec64);

/**
* put_itimerspec64 - convert &struct itimerspec64 to __kernel_itimerspec format
* and copy the latter to userspace
* @it: input &struct itimerspec64
* @uit: user's &struct __kernel_itimerspec
*
* Return: %0 on success or negative errno on error
*/
int put_itimerspec64(const struct itimerspec64 *it,
struct __kernel_itimerspec __user *uit)
{
Expand All @@ -887,6 +1019,13 @@ int put_itimerspec64(const struct itimerspec64 *it,
}
EXPORT_SYMBOL_GPL(put_itimerspec64);

/**
* get_old_itimerspec32 - get user's &struct old_itimerspec32 into kernel space
* @its: destination &struct itimerspec64
* @uits: user's &struct old_itimerspec32
*
* Return: %0 on success or negative errno on error
*/
int get_old_itimerspec32(struct itimerspec64 *its,
const struct old_itimerspec32 __user *uits)
{
Expand All @@ -898,6 +1037,14 @@ int get_old_itimerspec32(struct itimerspec64 *its,
}
EXPORT_SYMBOL_GPL(get_old_itimerspec32);

/**
* put_old_itimerspec32 - convert &struct itimerspec64 to &struct
* old_itimerspec32 and copy the latter to userspace
* @its: input &struct itimerspec64
* @uits: user's &struct old_itimerspec32
*
* Return: %0 on success or negative errno on error
*/
int put_old_itimerspec32(const struct itimerspec64 *its,
struct old_itimerspec32 __user *uits)
{
Expand Down

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