diff options
| -rw-r--r-- | Documentation/core-api/timekeeping.rst | 1 | ||||
| -rw-r--r-- | include/linux/timekeeping.h | 1 | ||||
| -rw-r--r-- | kernel/time/timekeeping.c | 17 |
3 files changed, 19 insertions, 0 deletions
diff --git a/Documentation/core-api/timekeeping.rst b/Documentation/core-api/timekeeping.rst index 729e24864fe7..22ec68f24421 100644 --- a/Documentation/core-api/timekeeping.rst +++ b/Documentation/core-api/timekeeping.rst @@ -132,6 +132,7 @@ Some additional variants exist for more specialized cases: .. c:function:: u64 ktime_get_mono_fast_ns( void ) u64 ktime_get_raw_fast_ns( void ) u64 ktime_get_boot_fast_ns( void ) + u64 ktime_get_tai_fast_ns( void ) u64 ktime_get_real_fast_ns( void ) These variants are safe to call from any context, including from diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index 78a98bdff76d..fe1e467ba046 100644 --- a/include/linux/timekeeping.h +++ b/include/linux/timekeeping.h @@ -177,6 +177,7 @@ static inline u64 ktime_get_raw_ns(void) extern u64 ktime_get_mono_fast_ns(void); extern u64 ktime_get_raw_fast_ns(void); extern u64 ktime_get_boot_fast_ns(void); +extern u64 ktime_get_tai_fast_ns(void); extern u64 ktime_get_real_fast_ns(void); /* diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index dcdcb85121e4..2c22023fbf5f 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -532,6 +532,23 @@ u64 notrace ktime_get_boot_fast_ns(void) } EXPORT_SYMBOL_GPL(ktime_get_boot_fast_ns); +/** + * ktime_get_tai_fast_ns - NMI safe and fast access to tai clock. + * + * The same limitations as described for ktime_get_boot_fast_ns() apply. The + * mono time and the TAI offset are not read atomically which may yield wrong + * readouts. However, an update of the TAI offset is an rare event e.g., caused + * by settime or adjtimex with an offset. The user of this function has to deal + * with the possibility of wrong timestamps in post processing. + */ +u64 notrace ktime_get_tai_fast_ns(void) +{ + struct timekeeper *tk = &tk_core.timekeeper; + + return (ktime_get_mono_fast_ns() + ktime_to_ns(data_race(tk->offs_tai))); +} +EXPORT_SYMBOL_GPL(ktime_get_tai_fast_ns); + static __always_inline u64 __ktime_get_real_fast(struct tk_fast *tkf, u64 *mono) { struct tk_read_base *tkr; |