time: Clean up offs_real/wall_to_mono and offs_boot/total_sleep_time updates
For performance reasons, we maintain ktime_t based duplicates of
wall_to_monotonic (offs_real) and total_sleep_time (offs_boot).
Since large problems could occur (such as the resume regression
on 3.5-rc7, or the leapsecond hrtimer issue) if these value
pairs were to be inconsistently updated, this patch this cleans
up how we modify these value pairs to ensure we are always
consistent.
As a side-effect this is also more efficient as we only
caulculate the duplicate values when they are changed,
rather then every update_wall_time call.
This also provides WARN_ONs to detect if future changes break
the invariants.
Signed-off-by: John Stultz <john.stultz@linaro.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Prarit Bhargava <prarit@redhat.com>
Link: http://lkml.kernel.org/r/1343414893-45779-5-git-send-email-john.stultz@linaro.org
[ Cleaned up minor style issues. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 05b37a5..4da6559 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -65,14 +65,14 @@
* used instead.
*/
struct timespec wall_to_monotonic;
- /* time spent in suspend */
- struct timespec total_sleep_time;
- /* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */
- struct timespec raw_time;
/* Offset clock monotonic -> clock realtime */
ktime_t offs_real;
+ /* time spent in suspend */
+ struct timespec total_sleep_time;
/* Offset clock monotonic -> clock boottime */
ktime_t offs_boot;
+ /* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */
+ struct timespec raw_time;
/* Seqlock for all timekeeper values */
seqlock_t lock;
};
@@ -117,6 +117,31 @@
tk->xtime_nsec += (u64)ts->tv_nsec << tk->shift;
}
+static void tk_set_wall_to_mono(struct timekeeper *tk, struct timespec wtm)
+{
+ struct timespec tmp;
+
+ /*
+ * Verify consistency of: offset_real = -wall_to_monotonic
+ * before modifying anything
+ */
+ set_normalized_timespec(&tmp, -tk->wall_to_monotonic.tv_sec,
+ -tk->wall_to_monotonic.tv_nsec);
+ WARN_ON_ONCE(tk->offs_real.tv64 != timespec_to_ktime(tmp).tv64);
+ tk->wall_to_monotonic = wtm;
+ set_normalized_timespec(&tmp, -wtm.tv_sec, -wtm.tv_nsec);
+ tk->offs_real = timespec_to_ktime(tmp);
+}
+
+static void tk_set_sleep_time(struct timekeeper *tk, struct timespec t)
+{
+ /* Verify consistency before modifying */
+ WARN_ON_ONCE(tk->offs_boot.tv64 != timespec_to_ktime(tk->total_sleep_time).tv64);
+
+ tk->total_sleep_time = t;
+ tk->offs_boot = timespec_to_ktime(t);
+}
+
/**
* timekeeper_setup_internals - Set up internals to use clocksource clock.
*
@@ -217,14 +242,6 @@
return nsec + arch_gettimeoffset();
}
-static void update_rt_offset(struct timekeeper *tk)
-{
- struct timespec tmp, *wtm = &tk->wall_to_monotonic;
-
- set_normalized_timespec(&tmp, -wtm->tv_sec, -wtm->tv_nsec);
- tk->offs_real = timespec_to_ktime(tmp);
-}
-
/* must hold write on timekeeper.lock */
static void timekeeping_update(struct timekeeper *tk, bool clearntp)
{
@@ -234,7 +251,6 @@
tk->ntp_error = 0;
ntp_clear();
}
- update_rt_offset(tk);
xt = tk_xtime(tk);
update_vsyscall(&xt, &tk->wall_to_monotonic, tk->clock, tk->mult);
}
@@ -419,8 +435,8 @@
ts_delta.tv_sec = tv->tv_sec - xt.tv_sec;
ts_delta.tv_nsec = tv->tv_nsec - xt.tv_nsec;
- timekeeper.wall_to_monotonic =
- timespec_sub(timekeeper.wall_to_monotonic, ts_delta);
+ tk_set_wall_to_mono(&timekeeper,
+ timespec_sub(timekeeper.wall_to_monotonic, ts_delta));
tk_set_xtime(&timekeeper, tv);
@@ -454,8 +470,8 @@
tk_xtime_add(&timekeeper, ts);
- timekeeper.wall_to_monotonic =
- timespec_sub(timekeeper.wall_to_monotonic, *ts);
+ tk_set_wall_to_mono(&timekeeper,
+ timespec_sub(timekeeper.wall_to_monotonic, *ts));
timekeeping_update(&timekeeper, true);
@@ -621,7 +637,7 @@
{
struct clocksource *clock;
unsigned long flags;
- struct timespec now, boot;
+ struct timespec now, boot, tmp;
read_persistent_clock(&now);
read_boot_clock(&boot);
@@ -642,23 +658,19 @@
if (boot.tv_sec == 0 && boot.tv_nsec == 0)
boot = tk_xtime(&timekeeper);
- set_normalized_timespec(&timekeeper.wall_to_monotonic,
- -boot.tv_sec, -boot.tv_nsec);
- update_rt_offset(&timekeeper);
- timekeeper.total_sleep_time.tv_sec = 0;
- timekeeper.total_sleep_time.tv_nsec = 0;
+ set_normalized_timespec(&tmp, -boot.tv_sec, -boot.tv_nsec);
+ tk_set_wall_to_mono(&timekeeper, tmp);
+
+ tmp.tv_sec = 0;
+ tmp.tv_nsec = 0;
+ tk_set_sleep_time(&timekeeper, tmp);
+
write_sequnlock_irqrestore(&timekeeper.lock, flags);
}
/* time in seconds when suspend began */
static struct timespec timekeeping_suspend_time;
-static void update_sleep_time(struct timespec t)
-{
- timekeeper.total_sleep_time = t;
- timekeeper.offs_boot = timespec_to_ktime(t);
-}
-
/**
* __timekeeping_inject_sleeptime - Internal function to add sleep interval
* @delta: pointer to a timespec delta value
@@ -674,10 +686,9 @@
"sleep delta value!\n");
return;
}
-
tk_xtime_add(tk, delta);
- tk->wall_to_monotonic = timespec_sub(tk->wall_to_monotonic, *delta);
- update_sleep_time(timespec_add(tk->total_sleep_time, *delta));
+ tk_set_wall_to_mono(tk, timespec_sub(tk->wall_to_monotonic, *delta));
+ tk_set_sleep_time(tk, timespec_add(tk->total_sleep_time, *delta));
}
/**
@@ -1018,11 +1029,18 @@
/* Figure out if its a leap sec and apply if needed */
leap = second_overflow(tk->xtime_sec);
- tk->xtime_sec += leap;
- tk->wall_to_monotonic.tv_sec -= leap;
- if (leap)
- clock_was_set_delayed();
+ if (unlikely(leap)) {
+ struct timespec ts;
+ tk->xtime_sec += leap;
+
+ ts.tv_sec = leap;
+ ts.tv_nsec = 0;
+ tk_set_wall_to_mono(tk,
+ timespec_sub(tk->wall_to_monotonic, ts));
+
+ clock_was_set_delayed();
+ }
}
}