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Subject[PATCH 10/16] time: Remove most of xtime_lock usage in timekeeping.c
Date
Now that ntp.c's locking is reworked, we can remove most
of the xtime_lock usage in timekeeping.c

The remaining xtime_lock presence is really for jiffies access
and the global load calculation.

CC: Thomas Gleixner <tglx@linutronix.de>
CC: Eric Dumazet <eric.dumazet@gmail.com>
CC: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
kernel/time/timekeeping.c | 44 +++++++++++++++-----------------------------
1 files changed, 15 insertions(+), 29 deletions(-)
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index f92e636..810b974 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -172,7 +172,6 @@ static inline s64 timekeeping_get_ns_raw(void)
return clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
}

-/* must hold xtime_lock */
void timekeeping_leap_insert(int leapsecond)
{
unsigned long flags;
@@ -368,13 +367,12 @@ EXPORT_SYMBOL(do_gettimeofday);
int do_settimeofday(const struct timespec *tv)
{
struct timespec ts_delta;
- unsigned long flags1,flags2;
+ unsigned long flags;

if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;

- write_seqlock_irqsave(&xtime_lock, flags1);
- write_seqlock_irqsave(&timekeeper.lock, flags2);
+ write_seqlock_irqsave(&timekeeper.lock, flags);

timekeeping_forward_now();

@@ -391,8 +389,7 @@ int do_settimeofday(const struct timespec *tv)
update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,
timekeeper.clock, timekeeper.mult);

- write_sequnlock_irqrestore(&timekeeper.lock, flags2);
- write_sequnlock_irqrestore(&xtime_lock, flags1);
+ write_sequnlock_irqrestore(&timekeeper.lock, flags);

/* signal hrtimers about time change */
clock_was_set();
@@ -411,13 +408,12 @@ EXPORT_SYMBOL(do_settimeofday);
*/
int timekeeping_inject_offset(struct timespec *ts)
{
- unsigned long flags1,flags2;
+ unsigned long flags;

if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;

- write_seqlock_irqsave(&xtime_lock, flags1);
- write_seqlock_irqsave(&timekeeper.lock, flags2);
+ write_seqlock_irqsave(&timekeeper.lock, flags);

timekeeping_forward_now();

@@ -431,8 +427,7 @@ int timekeeping_inject_offset(struct timespec *ts)
update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,
timekeeper.clock, timekeeper.mult);

- write_sequnlock_irqrestore(&timekeeper.lock, flags2);
- write_sequnlock_irqrestore(&xtime_lock, flags1);
+ write_sequnlock_irqrestore(&timekeeper.lock, flags);

/* signal hrtimers about time change */
clock_was_set();
@@ -594,9 +589,7 @@ void __init timekeeping_init(void)

seqlock_init(&timekeeper.lock);

- write_seqlock_irqsave(&xtime_lock, flags);
ntp_init();
- write_sequnlock_irqrestore(&xtime_lock, flags);

write_seqlock_irqsave(&timekeeper.lock, flags);
clock = clocksource_default_clock();
@@ -657,7 +650,7 @@ static void __timekeeping_inject_sleeptime(struct timespec *delta)
*/
void timekeeping_inject_sleeptime(struct timespec *delta)
{
- unsigned long flags1,flags2;
+ unsigned long flags;
struct timespec ts;

/* Make sure we don't set the clock twice */
@@ -665,8 +658,7 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
if (!(ts.tv_sec == 0 && ts.tv_nsec == 0))
return;

- write_seqlock_irqsave(&xtime_lock, flags1);
- write_seqlock_irqsave(&timekeeper.lock, flags2);
+ write_seqlock_irqsave(&timekeeper.lock, flags);

timekeeping_forward_now();

@@ -677,8 +669,7 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,
timekeeper.clock, timekeeper.mult);

- write_sequnlock_irqrestore(&timekeeper.lock, flags2);
- write_sequnlock_irqrestore(&xtime_lock, flags1);
+ write_sequnlock_irqrestore(&timekeeper.lock, flags);

/* signal hrtimers about time change */
clock_was_set();
@@ -694,15 +685,14 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
*/
static void timekeeping_resume(void)
{
- unsigned long flags1,flags2;
+ unsigned long flags;
struct timespec ts;

read_persistent_clock(&ts);

clocksource_resume();

- write_seqlock_irqsave(&xtime_lock, flags1);
- write_seqlock_irqsave(&timekeeper.lock, flags2);
+ write_seqlock_irqsave(&timekeeper.lock, flags);

if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) {
ts = timespec_sub(ts, timekeeping_suspend_time);
@@ -712,8 +702,7 @@ static void timekeeping_resume(void)
timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
timekeeper.ntp_error = 0;
timekeeping_suspended = 0;
- write_sequnlock_irqrestore(&timekeeper.lock, flags2);
- write_sequnlock_irqrestore(&xtime_lock, flags1);
+ write_sequnlock_irqrestore(&timekeeper.lock, flags);

touch_softlockup_watchdog();

@@ -725,14 +714,13 @@ static void timekeeping_resume(void)

static int timekeeping_suspend(void)
{
- unsigned long flags1,flags2;
+ unsigned long flags;
struct timespec delta, delta_delta;
static struct timespec old_delta;

read_persistent_clock(&timekeeping_suspend_time);

- write_seqlock_irqsave(&xtime_lock, flags1);
- write_seqlock_irqsave(&timekeeper.lock, flags2);
+ write_seqlock_irqsave(&timekeeper.lock, flags);
timekeeping_forward_now();
timekeeping_suspended = 1;

@@ -755,8 +743,7 @@ static int timekeeping_suspend(void)
timekeeping_suspend_time =
timespec_add(timekeeping_suspend_time, delta_delta);
}
- write_sequnlock_irqrestore(&timekeeper.lock, flags2);
- write_sequnlock_irqrestore(&xtime_lock, flags1);
+ write_sequnlock_irqrestore(&timekeeper.lock, flags);

clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
clocksource_suspend();
@@ -916,7 +903,6 @@ static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
/**
* update_wall_time - Uses the current clocksource to increment the wall time
*
- * Called from the timer interrupt, must hold a write on xtime_lock.
*/
static void update_wall_time(void)
{
--
1.7.3.2.146.gca209


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