Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer updates from Ingo Molnar:
 "The main changes in the timer code in this cycle were:

   - Clockevent updates:

      - timer-of framework cleanups. (Geert Uytterhoeven)

      - Use timer-of for the renesas-ostm and the device name to prevent
        name collision in case of multiple timers. (Geert Uytterhoeven)

      - Check if there is an error after calling of_clk_get in asm9260
        (Chuhong Yuan)

   - ABI fix: Zero out high order bits of nanoseconds on compat
     syscalls. This got broken a year ago, with apparently no side
     effects so far.

     Since the kernel would use random data otherwise I don't think we'd
     have other options but to fix the bug, even if there was a side
     effect to applications (Dmitry Safonov)

   - Optimize ns_to_timespec64() on 32-bit systems: move away from
     div_s64_rem() which can be slow, to div_u64_rem() which is faster
     (Arnd Bergmann)

   - Annotate KCSAN-reported false positive data races in
     hrtimer_is_queued() users by moving timer->state handling over to
     the READ_ONCE()/WRITE_ONCE() APIs. This documents these accesses
     (Eric Dumazet)

   - Misc cleanups and small fixes"

[ I undid the "ABI fix" and updated the comments instead. The reason
  there were apparently no side effects is that the fix was a no-op.

  The updated comment is to say _why_ it was a no-op.    - Linus ]

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  time: Zero the upper 32-bits in __kernel_timespec on 32-bit
  time: Rename tsk->real_start_time to ->start_boottime
  hrtimer: Remove the comment about not used HRTIMER_SOFTIRQ
  time: Fix spelling mistake in comment
  time: Optimize ns_to_timespec64()
  hrtimer: Annotate lockless access to timer->state
  clocksource/drivers/asm9260: Add a check for of_clk_get
  clocksource/drivers/renesas-ostm: Use unique device name instead of ostm
  clocksource/drivers/renesas-ostm: Convert to timer_of
  clocksource/drivers/timer-of: Use unique device name instead of timer
  clocksource/drivers/timer-of: Convert last full_name to %pOF

3 files changed, 23 insertions, 16 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 21c6c1e29b98..2508a4f238a3 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -2185,7 +2185,7 @@ static __latent_entropy struct task_struct *copy_process(
 	 */
 
 	p->start_time = ktime_get_ns();
-	p->real_start_time = ktime_get_boottime_ns();
+	p->start_boottime = ktime_get_boottime_ns();
 
 	/*
 	 * Make it visible to the rest of the system, but dont wake it up yet.
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 9e20873148c6..8de90ea31280 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -966,7 +966,8 @@ static int enqueue_hrtimer(struct hrtimer *timer,
 
 	base->cpu_base->active_bases |= 1 << base->index;
 
-	timer->state = HRTIMER_STATE_ENQUEUED;
+	/* Pairs with the lockless read in hrtimer_is_queued() */
+	WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED);
 
 	return timerqueue_add(&base->active, &timer->node);
 }
@@ -988,7 +989,8 @@ static void __remove_hrtimer(struct hrtimer *timer,
 	struct hrtimer_cpu_base *cpu_base = base->cpu_base;
 	u8 state = timer->state;
 
-	timer->state = newstate;
+	/* Pairs with the lockless read in hrtimer_is_queued() */
+	WRITE_ONCE(timer->state, newstate);
 	if (!(state & HRTIMER_STATE_ENQUEUED))
 		return;
 
@@ -1013,8 +1015,9 @@ static void __remove_hrtimer(struct hrtimer *timer,
 static inline int
 remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, bool restart)
 {
-	if (hrtimer_is_queued(timer)) {
-		u8 state = timer->state;
+	u8 state = timer->state;
+
+	if (state & HRTIMER_STATE_ENQUEUED) {
 		int reprogram;
 
 		/*
diff --git a/kernel/time/time.c b/kernel/time/time.c
index 58e312e7380f..704ccd9451b0 100644
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -179,7 +179,7 @@ int do_sys_settimeofday64(const struct timespec64 *tv, const struct timezone *tz
 		return error;
 
 	if (tz) {
-		/* Verify we're witin the +-15 hrs range */
+		/* Verify we're within the +-15 hrs range */
 		if (tz->tz_minuteswest > 15*60 || tz->tz_minuteswest < -15*60)
 			return -EINVAL;
 
@@ -548,18 +548,21 @@ EXPORT_SYMBOL(set_normalized_timespec64);
  */
 struct timespec64 ns_to_timespec64(const s64 nsec)
 {
-	struct timespec64 ts;
+	struct timespec64 ts = { 0, 0 };
 	s32 rem;
 
-	if (!nsec)
-		return (struct timespec64) {0, 0};
-
-	ts.tv_sec = div_s64_rem(nsec, NSEC_PER_SEC, &rem);
-	if (unlikely(rem < 0)) {
-		ts.tv_sec--;
-		rem += NSEC_PER_SEC;
+	if (likely(nsec > 0)) {
+		ts.tv_sec = div_u64_rem(nsec, NSEC_PER_SEC, &rem);
+		ts.tv_nsec = rem;
+	} else if (nsec < 0) {
+		/*
+		 * With negative times, tv_sec points to the earlier
+		 * second, and tv_nsec counts the nanoseconds since
+		 * then, so tv_nsec is always a positive number.
+		 */
+		ts.tv_sec = -div_u64_rem(-nsec - 1, NSEC_PER_SEC, &rem) - 1;
+		ts.tv_nsec = NSEC_PER_SEC - rem - 1;
 	}
-	ts.tv_nsec = rem;
 
 	return ts;
 }
@@ -878,10 +881,11 @@ int get_timespec64(struct timespec64 *ts,
 
 	ts->tv_sec = kts.tv_sec;
 
-	/* Zero out the padding for 32 bit systems or in compat mode */
+	/* Zero out the padding in compat mode */
 	if (in_compat_syscall())
 		kts.tv_nsec &= 0xFFFFFFFFUL;
 
+	/* In 32-bit mode, this drops the padding */
 	ts->tv_nsec = kts.tv_nsec;
 
 	return 0;