Messages in this thread Patch in this message | | | Date | Mon, 27 Oct 2014 10:38:04 +0530 | From | Heena Sirwani <> | Subject | [PATCH v2] timekeeping: Added a function to return tv_sec portion of ktime_get_real_ts64() |
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The following patch adds a function to return tv_sec portion of ktime_get_real_ts64() function in order to have a function that returns seconds as 64-bit integers instead of 32-bit integers to address the y2038 problem.
The function is similar to get_seconds() function except that it includes read_seqcount_retry loop which is required for 32-bit architectures. This is because 32-bit machines cannot access 64-bit tk->xtime_sec variable atomically, requiring two 32-bit register loads.
Signed-off-by: Heena Sirwani <heenasirwani@gmail.com> Reviewed-by: Arnd Bergmann <arnd@arndb.de> --- Changes in v2: - Removed the local variable nsecs as it was not required.
include/linux/timekeeping.h | 1 + kernel/time/timekeeping.c | 19 +++++++++++++++++++ 2 files changed, 20 insertions(+)
diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index 115d55e..91454de 100644 --- a/include/linux/timekeeping.h +++ b/include/linux/timekeeping.h @@ -29,6 +29,7 @@ struct timespec get_monotonic_coarse(void); extern void getrawmonotonic(struct timespec *ts); extern void ktime_get_ts64(struct timespec64 *ts); extern time64_t ktime_get_seconds(void); +extern time64_t ktime_get_real_seconds(void); extern int __getnstimeofday64(struct timespec64 *tv); extern void getnstimeofday64(struct timespec64 *tv); diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 93fc596..c17c620 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -673,6 +673,25 @@ time64_t ktime_get_seconds(void) } EXPORT_SYMBOL_GPL(ktime_get_seconds); +time64_t ktime_get_real_seconds(void) +{ + time64_t seconds; + struct timekeeper *tk = &tk_core.timekeeper; + unsigned int seq; + + if (IS_ENABLED(CONFIG_64BIT)) + return tk->xtime_sec; + + do { + seq = read_seqcount_begin(&tk_core.seq); + seconds = tk->xtime_sec; + + } while (read_seqcount_retry(&tk_core.seq, seq)); + + return seconds; +} +EXPORT_SYMBOL_GPL(ktime_get_real_seconds); + #ifdef CONFIG_NTP_PPS /** -- 1.9.1
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