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authorThomas Gleixner <tglx@linutronix.de>2013-02-21 22:51:38 +0000
committerJohn Stultz <john.stultz@linaro.org>2013-03-22 16:20:01 -0700
commit9a7a71b1d0968fc2bd602b7481cde1d4872e01ff (patch)
tree18954e171dcf260a7750ad6be2f70bac7ef63a78 /kernel/time/timekeeping.c
parent7e40672d930b369c1984457233ec5557aa53bfb8 (diff)
downloadlinaro-lsk-9a7a71b1d0968fc2bd602b7481cde1d4872e01ff.tar.gz
timekeeping: Split timekeeper_lock into lock and seqcount
We want to shorten the seqcount write hold time. So split the seqlock into a lock and a seqcount. Open code the seqwrite_lock in the places which matter and drop the sequence counter update where it's pointless. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> [jstultz: Merge fixups from CLOCK_TAI collisions] Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'kernel/time/timekeeping.c')
-rw-r--r--kernel/time/timekeeping.c132
1 files changed, 73 insertions, 59 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index caede71c0a3..5e048e030c6 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -26,7 +26,8 @@
#include "tick-internal.h"
static struct timekeeper timekeeper;
-static DEFINE_SEQLOCK(timekeeper_lock);
+static DEFINE_RAW_SPINLOCK(timekeeper_lock);
+static seqcount_t timekeeper_seq;
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;
@@ -204,8 +205,6 @@ static void update_pvclock_gtod(struct timekeeper *tk)
/**
* pvclock_gtod_register_notifier - register a pvclock timedata update listener
- *
- * Must hold write on timekeeper.lock
*/
int pvclock_gtod_register_notifier(struct notifier_block *nb)
{
@@ -213,11 +212,10 @@ int pvclock_gtod_register_notifier(struct notifier_block *nb)
unsigned long flags;
int ret;
- write_seqlock_irqsave(&timekeeper_lock, flags);
+ raw_spin_lock_irqsave(&timekeeper_lock, flags);
ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
- /* update timekeeping data */
update_pvclock_gtod(tk);
- write_sequnlock_irqrestore(&timekeeper_lock, flags);
+ raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
return ret;
}
@@ -226,23 +224,21 @@ EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
/**
* pvclock_gtod_unregister_notifier - unregister a pvclock
* timedata update listener
- *
- * Must hold write on timekeeper.lock
*/
int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
{
unsigned long flags;
int ret;
- write_seqlock_irqsave(&timekeeper_lock, flags);
+ raw_spin_lock_irqsave(&timekeeper_lock, flags);
ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
- write_sequnlock_irqrestore(&timekeeper_lock, flags);
+ raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
-/* must hold write on timekeeper.lock */
+/* must hold timekeeper_lock */
static void timekeeping_update(struct timekeeper *tk, bool clearntp)
{
if (clearntp) {
@@ -296,12 +292,12 @@ int __getnstimeofday(struct timespec *ts)
s64 nsecs = 0;
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
ts->tv_sec = tk->xtime_sec;
nsecs = timekeeping_get_ns(tk);
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
ts->tv_nsec = 0;
timespec_add_ns(ts, nsecs);
@@ -337,11 +333,11 @@ ktime_t ktime_get(void)
WARN_ON(timekeeping_suspended);
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
secs = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
nsecs = timekeeping_get_ns(tk) + tk->wall_to_monotonic.tv_nsec;
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
/*
* Use ktime_set/ktime_add_ns to create a proper ktime on
* 32-bit architectures without CONFIG_KTIME_SCALAR.
@@ -368,12 +364,12 @@ void ktime_get_ts(struct timespec *ts)
WARN_ON(timekeeping_suspended);
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
ts->tv_sec = tk->xtime_sec;
nsec = timekeeping_get_ns(tk);
tomono = tk->wall_to_monotonic;
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
ts->tv_sec += tomono.tv_sec;
ts->tv_nsec = 0;
@@ -397,12 +393,12 @@ void timekeeping_clocktai(struct timespec *ts)
WARN_ON(timekeeping_suspended);
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
ts->tv_sec = tk->xtime_sec + tk->tai_offset;
nsecs = timekeeping_get_ns(tk);
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
ts->tv_nsec = 0;
timespec_add_ns(ts, nsecs);
@@ -445,7 +441,7 @@ void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
WARN_ON_ONCE(timekeeping_suspended);
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
*ts_raw = tk->raw_time;
ts_real->tv_sec = tk->xtime_sec;
@@ -454,7 +450,7 @@ void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
nsecs_raw = timekeeping_get_ns_raw(tk);
nsecs_real = timekeeping_get_ns(tk);
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
timespec_add_ns(ts_raw, nsecs_raw);
timespec_add_ns(ts_real, nsecs_real);
@@ -494,7 +490,8 @@ int do_settimeofday(const struct timespec *tv)
if (!timespec_valid_strict(tv))
return -EINVAL;
- write_seqlock_irqsave(&timekeeper_lock, flags);
+ raw_spin_lock_irqsave(&timekeeper_lock, flags);
+ write_seqcount_begin(&timekeeper_seq);
timekeeping_forward_now(tk);
@@ -508,7 +505,8 @@ int do_settimeofday(const struct timespec *tv)
timekeeping_update(tk, true);
- write_sequnlock_irqrestore(&timekeeper_lock, flags);
+ write_seqcount_end(&timekeeper_seq);
+ raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
/* signal hrtimers about time change */
clock_was_set();
@@ -533,7 +531,8 @@ int timekeeping_inject_offset(struct timespec *ts)
if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;
- write_seqlock_irqsave(&timekeeper_lock, flags);
+ raw_spin_lock_irqsave(&timekeeper_lock, flags);
+ write_seqcount_begin(&timekeeper_seq);
timekeeping_forward_now(tk);
@@ -550,7 +549,8 @@ int timekeeping_inject_offset(struct timespec *ts)
error: /* even if we error out, we forwarded the time, so call update */
timekeeping_update(tk, true);
- write_sequnlock_irqrestore(&timekeeper_lock, flags);
+ write_seqcount_end(&timekeeper_seq);
+ raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
/* signal hrtimers about time change */
clock_was_set();
@@ -571,9 +571,9 @@ s32 timekeeping_get_tai_offset(void)
s32 ret;
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
ret = tk->tai_offset;
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
return ret;
}
@@ -597,9 +597,11 @@ void timekeeping_set_tai_offset(s32 tai_offset)
struct timekeeper *tk = &timekeeper;
unsigned long flags;
- write_seqlock_irqsave(&timekeeper_lock, flags);
+ raw_spin_lock_irqsave(&timekeeper_lock, flags);
+ write_seqcount_begin(&timekeeper_seq);
__timekeeping_set_tai_offset(tk, tai_offset);
- write_sequnlock_irqrestore(&timekeeper_lock, flags);
+ write_seqcount_end(&timekeeper_seq);
+ raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
}
/**
@@ -615,7 +617,8 @@ static int change_clocksource(void *data)
new = (struct clocksource *) data;
- write_seqlock_irqsave(&timekeeper_lock, flags);
+ raw_spin_lock_irqsave(&timekeeper_lock, flags);
+ write_seqcount_begin(&timekeeper_seq);
timekeeping_forward_now(tk);
if (!new->enable || new->enable(new) == 0) {
@@ -626,7 +629,8 @@ static int change_clocksource(void *data)
}
timekeeping_update(tk, true);
- write_sequnlock_irqrestore(&timekeeper_lock, flags);
+ write_seqcount_end(&timekeeper_seq);
+ raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
return 0;
}
@@ -676,11 +680,11 @@ void getrawmonotonic(struct timespec *ts)
s64 nsecs;
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
nsecs = timekeeping_get_ns_raw(tk);
*ts = tk->raw_time;
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
timespec_add_ns(ts, nsecs);
}
@@ -696,11 +700,11 @@ int timekeeping_valid_for_hres(void)
int ret;
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
ret = tk->clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
return ret;
}
@@ -715,11 +719,11 @@ u64 timekeeping_max_deferment(void)
u64 ret;
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
ret = tk->clock->max_idle_ns;
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
return ret;
}
@@ -784,7 +788,8 @@ void __init timekeeping_init(void)
ntp_init();
- write_seqlock_irqsave(&timekeeper_lock, flags);
+ raw_spin_lock_irqsave(&timekeeper_lock, flags);
+ write_seqcount_begin(&timekeeper_seq);
clock = clocksource_default_clock();
if (clock->enable)
clock->enable(clock);
@@ -803,7 +808,8 @@ void __init timekeeping_init(void)
tmp.tv_nsec = 0;
tk_set_sleep_time(tk, tmp);
- write_sequnlock_irqrestore(&timekeeper_lock, flags);
+ write_seqcount_end(&timekeeper_seq);
+ raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
}
/* time in seconds when suspend began */
@@ -851,7 +857,8 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
if (has_persistent_clock())
return;
- write_seqlock_irqsave(&timekeeper_lock, flags);
+ raw_spin_lock_irqsave(&timekeeper_lock, flags);
+ write_seqcount_begin(&timekeeper_seq);
timekeeping_forward_now(tk);
@@ -859,7 +866,8 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
timekeeping_update(tk, true);
- write_sequnlock_irqrestore(&timekeeper_lock, flags);
+ write_seqcount_end(&timekeeper_seq);
+ raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
/* signal hrtimers about time change */
clock_was_set();
@@ -886,7 +894,8 @@ static void timekeeping_resume(void)
clockevents_resume();
clocksource_resume();
- write_seqlock_irqsave(&timekeeper_lock, flags);
+ raw_spin_lock_irqsave(&timekeeper_lock, flags);
+ write_seqcount_begin(&timekeeper_seq);
/*
* After system resumes, we need to calculate the suspended time and
@@ -938,7 +947,8 @@ static void timekeeping_resume(void)
tk->ntp_error = 0;
timekeeping_suspended = 0;
timekeeping_update(tk, false);
- write_sequnlock_irqrestore(&timekeeper_lock, flags);
+ write_seqcount_end(&timekeeper_seq);
+ raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
touch_softlockup_watchdog();
@@ -957,7 +967,8 @@ static int timekeeping_suspend(void)
read_persistent_clock(&timekeeping_suspend_time);
- write_seqlock_irqsave(&timekeeper_lock, flags);
+ raw_spin_lock_irqsave(&timekeeper_lock, flags);
+ write_seqcount_begin(&timekeeper_seq);
timekeeping_forward_now(tk);
timekeeping_suspended = 1;
@@ -980,7 +991,8 @@ static int timekeeping_suspend(void)
timekeeping_suspend_time =
timespec_add(timekeeping_suspend_time, delta_delta);
}
- write_sequnlock_irqrestore(&timekeeper_lock, flags);
+ write_seqcount_end(&timekeeper_seq);
+ raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
clocksource_suspend();
@@ -1320,7 +1332,8 @@ static void update_wall_time(void)
int shift = 0, maxshift;
unsigned long flags;
- write_seqlock_irqsave(&timekeeper_lock, flags);
+ raw_spin_lock_irqsave(&timekeeper_lock, flags);
+ write_seqcount_begin(&timekeeper_seq);
/* Make sure we're fully resumed: */
if (unlikely(timekeeping_suspended))
@@ -1375,7 +1388,8 @@ static void update_wall_time(void)
timekeeping_update(tk, false);
out:
- write_sequnlock_irqrestore(&timekeeper_lock, flags);
+ write_seqcount_end(&timekeeper_seq);
+ raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
}
@@ -1423,13 +1437,13 @@ void get_monotonic_boottime(struct timespec *ts)
WARN_ON(timekeeping_suspended);
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
ts->tv_sec = tk->xtime_sec;
nsec = timekeeping_get_ns(tk);
tomono = tk->wall_to_monotonic;
sleep = tk->total_sleep_time;
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
ts->tv_sec += tomono.tv_sec + sleep.tv_sec;
ts->tv_nsec = 0;
@@ -1488,10 +1502,10 @@ struct timespec current_kernel_time(void)
unsigned long seq;
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
now = tk_xtime(tk);
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
return now;
}
@@ -1504,11 +1518,11 @@ struct timespec get_monotonic_coarse(void)
unsigned long seq;
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
now = tk_xtime(tk);
mono = tk->wall_to_monotonic;
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
now.tv_nsec + mono.tv_nsec);
@@ -1539,11 +1553,11 @@ void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
unsigned long seq;
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
*xtim = tk_xtime(tk);
*wtom = tk->wall_to_monotonic;
*sleep = tk->total_sleep_time;
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
}
#ifdef CONFIG_HIGH_RES_TIMERS
@@ -1564,7 +1578,7 @@ ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot,
u64 secs, nsecs;
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
secs = tk->xtime_sec;
nsecs = timekeeping_get_ns(tk);
@@ -1572,7 +1586,7 @@ ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot,
*offs_real = tk->offs_real;
*offs_boot = tk->offs_boot;
*offs_tai = tk->offs_tai;
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
now = ktime_add_ns(ktime_set(secs, 0), nsecs);
now = ktime_sub(now, *offs_real);
@@ -1590,9 +1604,9 @@ ktime_t ktime_get_monotonic_offset(void)
struct timespec wtom;
do {
- seq = read_seqbegin(&timekeeper_lock);
+ seq = read_seqcount_begin(&timekeeper_seq);
wtom = tk->wall_to_monotonic;
- } while (read_seqretry(&timekeeper_lock, seq));
+ } while (read_seqcount_retry(&timekeeper_seq, seq));
return timespec_to_ktime(wtom);
}