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jiffies: add kernel-doc for all APIs

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Add kernel-doc notation in <linux/jiffies.h> for interfaces that
don't already have it (i.e. most interfaces).

Fix some formatting and typos in other comments.

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/20230704052405.5089-2-rdunlap@infradead.org
This commit is contained in:
Randy Dunlap 2023-07-03 22:24:04 -07:00 committed by Jonathan Corbet
parent a1d115ab6b
commit 6d07a31fea
1 changed files with 176 additions and 21 deletions
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197
include/linux/jiffies.h
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@ -72,9 +72,15 @@ extern int register_refined_jiffies(long clock_tick_rate);
#endif
/*
* The 64-bit value is not atomic - you MUST NOT read it
* The 64-bit value is not atomic on 32-bit systems - you MUST NOT read it
* without sampling the sequence number in jiffies_lock.
* get_jiffies_64() will do this for you as appropriate.
*
* jiffies and jiffies_64 are at the same address for little-endian systems
* and for 64-bit big-endian systems.
* On 32-bit big-endian systems, jiffies is the lower 32 bits of jiffies_64
* (i.e., at address @jiffies_64 + 4).
* See arch/ARCH/kernel/vmlinux.lds.S
*/
extern u64 __cacheline_aligned_in_smp jiffies_64;
extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_arch_data jiffies;
@ -82,6 +88,14 @@ extern unsigned long volatile __cacheline_aligned_in_smp __jiffy_arch_data jiffi
#if (BITS_PER_LONG < 64)
u64 get_jiffies_64(void);
#else
/**
* get_jiffies_64 - read the 64-bit non-atomic jiffies_64 value
*
* When BITS_PER_LONG < 64, this uses sequence number sampling using
* jiffies_lock to protect the 64-bit read.
*
* Return: current 64-bit jiffies value
*/
static inline u64 get_jiffies_64(void)
{
return (u64)jiffies;
@ -89,39 +103,76 @@ static inline u64 get_jiffies_64(void)
#endif
/*
* These inlines deal with timer wrapping correctly. You are
* strongly encouraged to use them
* These inlines deal with timer wrapping correctly. You are
* strongly encouraged to use them:
* 1. Because people otherwise forget
* 2. Because if the timer wrap changes in future you won't have to
* alter your driver code.
*
* time_after(a,b) returns true if the time a is after time b.
*/
/**
* time_after - returns true if the time a is after time b.
* @a: first comparable as unsigned long
* @b: second comparable as unsigned long
*
* Do this with "<0" and ">=0" to only test the sign of the result. A
* good compiler would generate better code (and a really good compiler
* wouldn't care). Gcc is currently neither.
*
* Return: %true is time a is after time b, otherwise %false.
*/
#define time_after(a,b) \
(typecheck(unsigned long, a) && \
typecheck(unsigned long, b) && \
((long)((b) - (a)) < 0))
/**
* time_before - returns true if the time a is before time b.
* @a: first comparable as unsigned long
* @b: second comparable as unsigned long
*
* Return: %true is time a is before time b, otherwise %false.
*/
#define time_before(a,b) time_after(b,a)
/**
* time_after_eq - returns true if the time a is after or the same as time b.
* @a: first comparable as unsigned long
* @b: second comparable as unsigned long
*
* Return: %true is time a is after or the same as time b, otherwise %false.
*/
#define time_after_eq(a,b) \
(typecheck(unsigned long, a) && \
typecheck(unsigned long, b) && \
((long)((a) - (b)) >= 0))
/**
* time_before_eq - returns true if the time a is before or the same as time b.
* @a: first comparable as unsigned long
* @b: second comparable as unsigned long
*
* Return: %true is time a is before or the same as time b, otherwise %false.
*/
#define time_before_eq(a,b) time_after_eq(b,a)
/*
* Calculate whether a is in the range of [b, c].
/**
* time_in_range - Calculate whether a is in the range of [b, c].
* @a: time to test
* @b: beginning of the range
* @c: end of the range
*
* Return: %true is time a is in the range [b, c], otherwise %false.
*/
#define time_in_range(a,b,c) \
(time_after_eq(a,b) && \
time_before_eq(a,c))
/*
* Calculate whether a is in the range of [b, c).
/**
* time_in_range_open - Calculate whether a is in the range of [b, c).
* @a: time to test
* @b: beginning of the range
* @c: end of the range
*
* Return: %true is time a is in the range [b, c), otherwise %false.
*/
#define time_in_range_open(a,b,c) \
(time_after_eq(a,b) && \
@ -129,45 +180,138 @@ static inline u64 get_jiffies_64(void)
/* Same as above, but does so with platform independent 64bit types.
* These must be used when utilizing jiffies_64 (i.e. return value of
* get_jiffies_64() */
* get_jiffies_64()). */
/**
* time_after64 - returns true if the time a is after time b.
* @a: first comparable as __u64
* @b: second comparable as __u64
*
* This must be used when utilizing jiffies_64 (i.e. return value of
* get_jiffies_64()).
*
* Return: %true is time a is after time b, otherwise %false.
*/
#define time_after64(a,b) \
(typecheck(__u64, a) && \
typecheck(__u64, b) && \
((__s64)((b) - (a)) < 0))
/**
* time_before64 - returns true if the time a is before time b.
* @a: first comparable as __u64
* @b: second comparable as __u64
*
* This must be used when utilizing jiffies_64 (i.e. return value of
* get_jiffies_64()).
*
* Return: %true is time a is before time b, otherwise %false.
*/
#define time_before64(a,b) time_after64(b,a)
/**
* time_after_eq64 - returns true if the time a is after or the same as time b.
* @a: first comparable as __u64
* @b: second comparable as __u64
*
* This must be used when utilizing jiffies_64 (i.e. return value of
* get_jiffies_64()).
*
* Return: %true is time a is after or the same as time b, otherwise %false.
*/
#define time_after_eq64(a,b) \
(typecheck(__u64, a) && \
typecheck(__u64, b) && \
((__s64)((a) - (b)) >= 0))
/**
* time_before_eq64 - returns true if the time a is before or the same as time b.
* @a: first comparable as __u64
* @b: second comparable as __u64
*
* This must be used when utilizing jiffies_64 (i.e. return value of
* get_jiffies_64()).
*
* Return: %true is time a is before or the same as time b, otherwise %false.
*/
#define time_before_eq64(a,b) time_after_eq64(b,a)
/**
* time_in_range64 - Calculate whether a is in the range of [b, c].
* @a: time to test
* @b: beginning of the range
* @c: end of the range
*
* Return: %true is time a is in the range [b, c], otherwise %false.
*/
#define time_in_range64(a, b, c) \
(time_after_eq64(a, b) && \
time_before_eq64(a, c))
/*
* These four macros compare jiffies and 'a' for convenience.
* These eight macros compare jiffies[_64] and 'a' for convenience.
*/
/* time_is_before_jiffies(a) return true if a is before jiffies */
/**
* time_is_before_jiffies - return true if a is before jiffies
* @a: time (unsigned long) to compare to jiffies
*
* Return: %true is time a is before jiffies, otherwise %false.
*/
#define time_is_before_jiffies(a) time_after(jiffies, a)
/**
* time_is_before_jiffies64 - return true if a is before jiffies_64
* @a: time (__u64) to compare to jiffies_64
*
* Return: %true is time a is before jiffies_64, otherwise %false.
*/
#define time_is_before_jiffies64(a) time_after64(get_jiffies_64(), a)
/* time_is_after_jiffies(a) return true if a is after jiffies */
/**
* time_is_after_jiffies - return true if a is after jiffies
* @a: time (unsigned long) to compare to jiffies
*
* Return: %true is time a is after jiffies, otherwise %false.
*/
#define time_is_after_jiffies(a) time_before(jiffies, a)
/**
* time_is_after_jiffies64 - return true if a is after jiffies_64
* @a: time (__u64) to compare to jiffies_64
*
* Return: %true is time a is after jiffies_64, otherwise %false.
*/
#define time_is_after_jiffies64(a) time_before64(get_jiffies_64(), a)
/* time_is_before_eq_jiffies(a) return true if a is before or equal to jiffies*/
/**
* time_is_before_eq_jiffies - return true if a is before or equal to jiffies
* @a: time (unsigned long) to compare to jiffies
*
* Return: %true is time a is before or the same as jiffies, otherwise %false.
*/
#define time_is_before_eq_jiffies(a) time_after_eq(jiffies, a)
/**
* time_is_before_eq_jiffies64 - return true if a is before or equal to jiffies_64
* @a: time (__u64) to compare to jiffies_64
*
* Return: %true is time a is before or the same jiffies_64, otherwise %false.
*/
#define time_is_before_eq_jiffies64(a) time_after_eq64(get_jiffies_64(), a)
/* time_is_after_eq_jiffies(a) return true if a is after or equal to jiffies*/
/**
* time_is_after_eq_jiffies - return true if a is after or equal to jiffies
* @a: time (unsigned long) to compare to jiffies
*
* Return: %true is time a is after or the same as jiffies, otherwise %false.
*/
#define time_is_after_eq_jiffies(a) time_before_eq(jiffies, a)
/**
* time_is_after_eq_jiffies64 - return true if a is after or equal to jiffies_64
* @a: time (__u64) to compare to jiffies_64
*
* Return: %true is time a is after or the same as jiffies_64, otherwise %false.
*/
#define time_is_after_eq_jiffies64(a) time_before_eq64(get_jiffies_64(), a)
/*
* Have the 32 bit jiffies value wrap 5 minutes after boot
* Have the 32-bit jiffies value wrap 5 minutes after boot
* so jiffies wrap bugs show up earlier.
*/
#define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ))
@ -278,7 +422,7 @@ extern unsigned long preset_lpj;
#if BITS_PER_LONG < 64
# define MAX_SEC_IN_JIFFIES \
(long)((u64)((u64)MAX_JIFFY_OFFSET * TICK_NSEC) / NSEC_PER_SEC)
#else /* take care of overflow on 64 bits machines */
#else /* take care of overflow on 64-bit machines */
# define MAX_SEC_IN_JIFFIES \
(SH_DIV((MAX_JIFFY_OFFSET >> SEC_JIFFIE_SC) * TICK_NSEC, NSEC_PER_SEC, 1) - 1)
@ -290,6 +434,12 @@ extern unsigned long preset_lpj;
extern unsigned int jiffies_to_msecs(const unsigned long j);
extern unsigned int jiffies_to_usecs(const unsigned long j);
/**
* jiffies_to_nsecs - Convert jiffies to nanoseconds
* @j: jiffies value
*
* Return: nanoseconds value
*/
static inline u64 jiffies_to_nsecs(const unsigned long j)
{
return (u64)jiffies_to_usecs(j) * NSEC_PER_USEC;
@ -353,12 +503,14 @@ static inline 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
* 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 HZ range specific helpers _msecs_to_jiffies() are called both
* The HZ range specific helpers _msecs_to_jiffies() are called both
* directly here and from __msecs_to_jiffies() in the case where
* constant folding is not possible.
*
* Return: jiffies value
*/
static __always_inline unsigned long msecs_to_jiffies(const unsigned int m)
{
@ -400,12 +552,14 @@ static inline unsigned long _usecs_to_jiffies(const unsigned int u)
*
* usecs_to_jiffies() checks for the passed in value being a constant
* via __builtin_constant_p() allowing gcc to eliminate most of the
* code, __usecs_to_jiffies() is called if the value passed does not
* code. __usecs_to_jiffies() is called if the value passed does not
* allow constant folding and the actual conversion must be done at
* runtime.
* the HZ range specific helpers _usecs_to_jiffies() are called both
* The HZ range specific helpers _usecs_to_jiffies() are called both
* directly here and from __msecs_to_jiffies() in the case where
* constant folding is not possible.
*
* Return: jiffies value
*/
static __always_inline unsigned long usecs_to_jiffies(const unsigned int u)
{
@ -422,6 +576,7 @@ extern unsigned long timespec64_to_jiffies(const struct timespec64 *value);
extern void jiffies_to_timespec64(const unsigned long jiffies,
struct timespec64 *value);
extern clock_t jiffies_to_clock_t(unsigned long x);
static inline clock_t jiffies_delta_to_clock_t(long delta)
{
return jiffies_to_clock_t(max(0L, delta));