[RFC v4 22/22] timekeeping: inform clockevents about freq adjustments

From: Nicolai Stange
Date: Mon Aug 22 2016 - 19:34:41 EST


Upon adjustments of the monotonic clock's frequencies from the
timekeeping core, the clockevents devices' ->mult_adjusted should be
changed accordingly, too.

Introduce clockevents_adjust_all_freqs() which traverses all registered
clockevent devices and recalculates their ->mult_adjusted based on the
monotonic clock's current frequency.

Call clockevents_adjust_all_freqs() from timekeeping_apply_adjustment().

Signed-off-by: Nicolai Stange <nicstange@xxxxxxxxx>
---
kernel/time/clockevents.c | 25 +++++++++++++++++++++++++
kernel/time/tick-internal.h | 1 +
kernel/time/timekeeping.c | 3 +++
3 files changed, 29 insertions(+)

diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index ee7cd40..8f58565 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -561,6 +561,31 @@ void __clockevents_adjust_freq(struct clock_event_device *dev)
dev->shift));
}

+void clockevents_adjust_all_freqs(u32 mult_cs_mono, u32 mult_cs_raw)
+{
+ u32 last_mult_raw = 0, last_mult_adjusted = 0;
+ u32 mult_raw;
+ unsigned long flags;
+ struct clock_event_device *dev;
+
+ raw_spin_lock_irqsave(&clockevents_lock, flags);
+ list_for_each_entry(dev, &clockevent_devices, list) {
+ if (!(dev->features & CLOCK_EVT_FEAT_ONESHOT))
+ continue;
+
+ mult_raw = dev->mult;
+ if (mult_raw != last_mult_raw) {
+ last_mult_raw = mult_raw;
+ last_mult_adjusted =
+ __clockevents_calc_adjust_freq(mult_raw,
+ mult_cs_mono,
+ mult_cs_raw);
+ }
+ dev->mult_adjusted = last_mult_adjusted;
+ }
+ raw_spin_unlock_irqrestore(&clockevents_lock, flags);
+}
+
int __clockevents_update_freq(struct clock_event_device *dev, u32 freq)
{
clockevents_config(dev, freq);
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 0b29d23..9162671 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -56,6 +56,7 @@ extern int clockevents_program_event(struct clock_event_device *dev,
ktime_t expires, bool force);
extern void clockevents_handle_noop(struct clock_event_device *dev);
extern int __clockevents_update_freq(struct clock_event_device *dev, u32 freq);
+extern void clockevents_adjust_all_freqs(u32 mult_cs_mono, u32 mult_cs_raw);
extern void timekeeping_get_mono_mult(u32 *mult_cs_mono, u32 *mult_cs_raw);
extern ssize_t sysfs_get_uname(const char *buf, char *dst, size_t cnt);

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 6eac5b5..8d378b9 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1845,6 +1845,9 @@ static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk,
tk->xtime_interval += interval;
tk->tkr_mono.xtime_nsec -= offset;
tk->ntp_error -= (interval - offset) << tk->ntp_error_shift;
+
+ clockevents_adjust_all_freqs(tk->tkr_mono.mult,
+ tk->tkr_mono.clock->mult);
}

/*
--
2.9.2