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authorLinus Torvalds <torvalds@linux-foundation.org>2014-12-10 10:13:28 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-12-10 10:13:28 -0800
commitd82012695ef29e4e1c8153ccf43098ec8e50369e (patch)
tree80a379de91a332a6dca5f035d10421bb6d988b80 /kernel/time/timekeeping.c
parent3eb5b893ebec7325ac9e6b8e4864af89a9ca1ed1 (diff)
parentdbe7aa622db96b5cd601f59d09c4f00b98b76079 (diff)
downloadlinux-d82012695ef29e4e1c8153ccf43098ec8e50369e.tar.bz2
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/timekeeping.c')
-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);
*/
static inline void tk_update_ktime_data(struct timekeeper *tk)
{
- s64 nsec;
+ u64 seconds;
+ u32 nsec;
/*
* The xtime based monotonic readout is:
@@ -426,13 +427,22 @@ static inline void tk_update_ktime_data(struct timekeeper *tk)
* nsec = base_mono + now();
* ==> base_mono = (xtime_sec + wtm_sec) * 1e9 + wtm_nsec
*/
- nsec = (s64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
- nsec *= NSEC_PER_SEC;
- nsec += tk->wall_to_monotonic.tv_nsec;
- tk->tkr.base_mono = ns_to_ktime(nsec);
+ seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
+ nsec = (u32) tk->wall_to_monotonic.tv_nsec;
+ tk->tkr.base_mono = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);
/* Update the monotonic raw base */
tk->base_raw = timespec64_to_ktime(tk->raw_time);
+
+ /*
+ * The sum of the nanoseconds portions of xtime and
+ * wall_to_monotonic can be greater/equal one second. Take
+ * this into account before updating tk->ktime_sec.
+ */
+ nsec += (u32)(tk->tkr.xtime_nsec >> tk->tkr.shift);
+ if (nsec >= NSEC_PER_SEC)
+ seconds++;
+ tk->ktime_sec = seconds;
}
/* must hold timekeeper_lock */
@@ -648,6 +658,54 @@ void ktime_get_ts64(struct timespec64 *ts)
}
EXPORT_SYMBOL_GPL(ktime_get_ts64);
+/**
+ * ktime_get_seconds - Get the seconds portion of CLOCK_MONOTONIC
+ *
+ * Returns the seconds portion of CLOCK_MONOTONIC with a single non
+ * serialized read. tk->ktime_sec is of type 'unsigned long' so this
+ * works on both 32 and 64 bit systems. On 32 bit systems the readout
+ * covers ~136 years of uptime which should be enough to prevent
+ * premature wrap arounds.
+ */
+time64_t ktime_get_seconds(void)
+{
+ struct timekeeper *tk = &tk_core.timekeeper;
+
+ WARN_ON(timekeeping_suspended);
+ return tk->ktime_sec;
+}
+EXPORT_SYMBOL_GPL(ktime_get_seconds);
+
+/**
+ * ktime_get_real_seconds - Get the seconds portion of CLOCK_REALTIME
+ *
+ * Returns the wall clock seconds since 1970. This replaces the
+ * get_seconds() interface which is not y2038 safe on 32bit systems.
+ *
+ * For 64bit systems the fast access to tk->xtime_sec is preserved. On
+ * 32bit systems the access must be protected with the sequence
+ * counter to provide "atomic" access to the 64bit tk->xtime_sec
+ * value.
+ */
+time64_t ktime_get_real_seconds(void)
+{
+ struct timekeeper *tk = &tk_core.timekeeper;
+ time64_t seconds;
+ 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
/**