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authorLinus Torvalds <torvalds@linux-foundation.org>2014-12-10 13:13:28 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-10 13:13:28 -0500
commitd82012695ef29e4e1c8153ccf43098ec8e50369e (patch)
tree80a379de91a332a6dca5f035d10421bb6d988b80 /kernel/time
parent3eb5b893ebec7325ac9e6b8e4864af89a9ca1ed1 (diff)
parentdbe7aa622db96b5cd601f59d09c4f00b98b76079 (diff)
Merge branch 'timers-2038-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull more 2038 timer work from Thomas Gleixner: "Two more patches for the ongoing 2038 work: - New accessors to clock MONOTONIC and REALTIME seconds This is a seperate branch as Arnd has follow up work depending on this" * 'timers-2038-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: timekeeping: Provide y2038 safe accessor to the seconds portion of CLOCK_REALTIME timekeeping: Provide fast accessor to the seconds part of CLOCK_MONOTONIC
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/timekeeping.c68
1 files changed, 63 insertions, 5 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 2dc0646258ae..6a931852082f 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -417,7 +417,8 @@ EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
417 */ 417 */
418static inline void tk_update_ktime_data(struct timekeeper *tk) 418static inline void tk_update_ktime_data(struct timekeeper *tk)
419{ 419{
420 s64 nsec; 420 u64 seconds;
421 u32 nsec;
421 422
422 /* 423 /*
423 * The xtime based monotonic readout is: 424 * The xtime based monotonic readout is:
@@ -426,13 +427,22 @@ static inline void tk_update_ktime_data(struct timekeeper *tk)
426 * nsec = base_mono + now(); 427 * nsec = base_mono + now();
427 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec 428 * ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
428 */ 429 */
429 nsec = (s64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec); 430 seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
430 nsec *= NSEC_PER_SEC; 431 nsec = (u32) tk->wall_to_monotonic.tv_nsec;
431 nsec += tk->wall_to_monotonic.tv_nsec; 432 tk->tkr.base_mono = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
432 tk->tkr.base_mono = ns_to_ktime(nsec);
433 433
434 /* Update the monotonic raw base */ 434 /* Update the monotonic raw base */
435 tk->base_raw = timespec64_to_ktime(tk->raw_time); 435 tk->base_raw = timespec64_to_ktime(tk->raw_time);
436
437 /*
438 * The sum of the nanoseconds portions of xtime and
439 * wall_to_monotonic can be greater/equal one second. Take
440 * this into account before updating tk->ktime_sec.
441 */
442 nsec += (u32)(tk->tkr.xtime_nsec >> tk->tkr.shift);
443 if (nsec >= NSEC_PER_SEC)
444 seconds++;
445 tk->ktime_sec = seconds;
436} 446}
437 447
438/* must hold timekeeper_lock */ 448/* must hold timekeeper_lock */
@@ -648,6 +658,54 @@ void ktime_get_ts64(struct timespec64 *ts)
648} 658}
649EXPORT_SYMBOL_GPL(ktime_get_ts64); 659EXPORT_SYMBOL_GPL(ktime_get_ts64);
650 660
661/**
662 * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
663 *
664 * Returns the seconds portion of CLOCK_MONOTONIC with a single non
665 * serialized read. tk->ktime_sec is of type 'unsigned long' so this
666 * works on both 32 and 64 bit systems. On 32 bit systems the readout
667 * covers ~136 years of uptime which should be enough to prevent
668 * premature wrap arounds.
669 */
670time64_t ktime_get_seconds(void)
671{
672 struct timekeeper *tk = &tk_core.timekeeper;
673
674 WARN_ON(timekeeping_suspended);
675 return tk->ktime_sec;
676}
677EXPORT_SYMBOL_GPL(ktime_get_seconds);
678
679/**
680 * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
681 *
682 * Returns the wall clock seconds since 1970. This replaces the
683 * get_seconds() interface which is not y2038 safe on 32bit systems.
684 *
685 * For 64bit systems the fast access to tk->xtime_sec is preserved. On
686 * 32bit systems the access must be protected with the sequence
687 * counter to provide "atomic" access to the 64bit tk->xtime_sec
688 * value.
689 */
690time64_t ktime_get_real_seconds(void)
691{
692 struct timekeeper *tk = &tk_core.timekeeper;
693 time64_t seconds;
694 unsigned int seq;
695
696 if (IS_ENABLED(CONFIG_64BIT))
697 return tk->xtime_sec;
698
699 do {
700 seq = read_seqcount_begin(&tk_core.seq);
701 seconds = tk->xtime_sec;
702
703 } while (read_seqcount_retry(&tk_core.seq, seq));
704
705 return seconds;
706}
707EXPORT_SYMBOL_GPL(ktime_get_real_seconds);
708
651#ifdef CONFIG_NTP_PPS 709#ifdef CONFIG_NTP_PPS
652 710
653/** 711/**