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WSL2-Linux-Kernel
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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>
This commit is contained in:
Thomas Gleixner 2013-02-21 22:51:38 +00:00 коммит произвёл John Stultz
Родитель 7e40672d93
Коммит 9a7a71b1d0
1 изменённых файлов: 73 добавлений и 59 удалений
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132
kernel/time/timekeeping.c
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@ -26,7 +26,8 @@
#include "tick-internal.h" #include "tick-internal.h"
static struct timekeeper timekeeper; 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 */ /* flag for if timekeeping is suspended */
int __read_mostly timekeeping_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 * 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) 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; unsigned long flags;
int ret; int ret;
write_seqlock_irqsave(&timekeeper_lock, flags); raw_spin_lock_irqsave(&timekeeper_lock, flags);
ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb); ret = raw_notifier_chain_register(&pvclock_gtod_chain, nb);
/* update timekeeping data */
update_pvclock_gtod(tk); update_pvclock_gtod(tk);
write_sequnlock_irqrestore(&timekeeper_lock, flags); raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
return ret; return ret;
} }
@ -226,23 +224,21 @@ EXPORT_SYMBOL_GPL(pvclock_gtod_register_notifier);
/** /**
* pvclock_gtod_unregister_notifier - unregister a pvclock * pvclock_gtod_unregister_notifier - unregister a pvclock
* timedata update listener * timedata update listener
*
* Must hold write on timekeeper.lock
*/ */
int pvclock_gtod_unregister_notifier(struct notifier_block *nb) int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
{ {
unsigned long flags; unsigned long flags;
int ret; int ret;
write_seqlock_irqsave(&timekeeper_lock, flags); raw_spin_lock_irqsave(&timekeeper_lock, flags);
ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb); ret = raw_notifier_chain_unregister(&pvclock_gtod_chain, nb);
write_sequnlock_irqrestore(&timekeeper_lock, flags); raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
return ret; return ret;
} }
EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier); 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) static void timekeeping_update(struct timekeeper *tk, bool clearntp)
{ {
if (clearntp) { if (clearntp) {
@ -296,12 +292,12 @@ int __getnstimeofday(struct timespec *ts)
s64 nsecs = 0; s64 nsecs = 0;
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
ts->tv_sec = tk->xtime_sec; ts->tv_sec = tk->xtime_sec;
nsecs = timekeeping_get_ns(tk); nsecs = timekeeping_get_ns(tk);
} while (read_seqretry(&timekeeper_lock, seq)); } while (read_seqcount_retry(&timekeeper_seq, seq));
ts->tv_nsec = 0; ts->tv_nsec = 0;
timespec_add_ns(ts, nsecs); timespec_add_ns(ts, nsecs);
@ -337,11 +333,11 @@ ktime_t ktime_get(void)
WARN_ON(timekeeping_suspended); WARN_ON(timekeeping_suspended);
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
secs = tk->xtime_sec + tk->wall_to_monotonic.tv_sec; secs = tk->xtime_sec + tk->wall_to_monotonic.tv_sec;
nsecs = timekeeping_get_ns(tk) + tk->wall_to_monotonic.tv_nsec; 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 * Use ktime_set/ktime_add_ns to create a proper ktime on
* 32-bit architectures without CONFIG_KTIME_SCALAR. * 32-bit architectures without CONFIG_KTIME_SCALAR.
@ -368,12 +364,12 @@ void ktime_get_ts(struct timespec *ts)
WARN_ON(timekeeping_suspended); WARN_ON(timekeeping_suspended);
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
ts->tv_sec = tk->xtime_sec; ts->tv_sec = tk->xtime_sec;
nsec = timekeeping_get_ns(tk); nsec = timekeeping_get_ns(tk);
tomono = tk->wall_to_monotonic; 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_sec += tomono.tv_sec;
ts->tv_nsec = 0; ts->tv_nsec = 0;
@ -397,12 +393,12 @@ void timekeeping_clocktai(struct timespec *ts)
WARN_ON(timekeeping_suspended); WARN_ON(timekeeping_suspended);
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
ts->tv_sec = tk->xtime_sec + tk->tai_offset; ts->tv_sec = tk->xtime_sec + tk->tai_offset;
nsecs = timekeeping_get_ns(tk); nsecs = timekeeping_get_ns(tk);
} while (read_seqretry(&timekeeper_lock, seq)); } while (read_seqcount_retry(&timekeeper_seq, seq));
ts->tv_nsec = 0; ts->tv_nsec = 0;
timespec_add_ns(ts, nsecs); 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); WARN_ON_ONCE(timekeeping_suspended);
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
*ts_raw = tk->raw_time; *ts_raw = tk->raw_time;
ts_real->tv_sec = tk->xtime_sec; 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_raw = timekeeping_get_ns_raw(tk);
nsecs_real = timekeeping_get_ns(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_raw, nsecs_raw);
timespec_add_ns(ts_real, nsecs_real); timespec_add_ns(ts_real, nsecs_real);
@ -494,7 +490,8 @@ int do_settimeofday(const struct timespec *tv)
if (!timespec_valid_strict(tv)) if (!timespec_valid_strict(tv))
return -EINVAL; return -EINVAL;
write_seqlock_irqsave(&timekeeper_lock, flags); raw_spin_lock_irqsave(&timekeeper_lock, flags);
write_seqcount_begin(&timekeeper_seq);
timekeeping_forward_now(tk); timekeeping_forward_now(tk);
@ -508,7 +505,8 @@ int do_settimeofday(const struct timespec *tv)
timekeeping_update(tk, true); 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 */ /* signal hrtimers about time change */
clock_was_set(); clock_was_set();
@ -533,7 +531,8 @@ int timekeeping_inject_offset(struct timespec *ts)
if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC) if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
return -EINVAL; return -EINVAL;
write_seqlock_irqsave(&timekeeper_lock, flags); raw_spin_lock_irqsave(&timekeeper_lock, flags);
write_seqcount_begin(&timekeeper_seq);
timekeeping_forward_now(tk); 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 */ error: /* even if we error out, we forwarded the time, so call update */
timekeeping_update(tk, true); 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 */ /* signal hrtimers about time change */
clock_was_set(); clock_was_set();
@ -571,9 +571,9 @@ s32 timekeeping_get_tai_offset(void)
s32 ret; s32 ret;
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
ret = tk->tai_offset; ret = tk->tai_offset;
} while (read_seqretry(&timekeeper_lock, seq)); } while (read_seqcount_retry(&timekeeper_seq, seq));
return ret; return ret;
} }
@ -597,9 +597,11 @@ void timekeeping_set_tai_offset(s32 tai_offset)
struct timekeeper *tk = &timekeeper; struct timekeeper *tk = &timekeeper;
unsigned long flags; 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); __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; 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); timekeeping_forward_now(tk);
if (!new->enable || new->enable(new) == 0) { if (!new->enable || new->enable(new) == 0) {
@ -626,7 +629,8 @@ static int change_clocksource(void *data)
} }
timekeeping_update(tk, true); timekeeping_update(tk, true);
write_sequnlock_irqrestore(&timekeeper_lock, flags); write_seqcount_end(&timekeeper_seq);
raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
return 0; return 0;
} }
@ -676,11 +680,11 @@ void getrawmonotonic(struct timespec *ts)
s64 nsecs; s64 nsecs;
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
nsecs = timekeeping_get_ns_raw(tk); nsecs = timekeeping_get_ns_raw(tk);
*ts = tk->raw_time; *ts = tk->raw_time;
} while (read_seqretry(&timekeeper_lock, seq)); } while (read_seqcount_retry(&timekeeper_seq, seq));
timespec_add_ns(ts, nsecs); timespec_add_ns(ts, nsecs);
} }
@ -696,11 +700,11 @@ int timekeeping_valid_for_hres(void)
int ret; int ret;
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
ret = tk->clock->flags & CLOCK_SOURCE_VALID_FOR_HRES; ret = tk->clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
} while (read_seqretry(&timekeeper_lock, seq)); } while (read_seqcount_retry(&timekeeper_seq, seq));
return ret; return ret;
} }
@ -715,11 +719,11 @@ u64 timekeeping_max_deferment(void)
u64 ret; u64 ret;
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
ret = tk->clock->max_idle_ns; ret = tk->clock->max_idle_ns;
} while (read_seqretry(&timekeeper_lock, seq)); } while (read_seqcount_retry(&timekeeper_seq, seq));
return ret; return ret;
} }
@ -784,7 +788,8 @@ void __init timekeeping_init(void)
ntp_init(); ntp_init();
write_seqlock_irqsave(&timekeeper_lock, flags); raw_spin_lock_irqsave(&timekeeper_lock, flags);
write_seqcount_begin(&timekeeper_seq);
clock = clocksource_default_clock(); clock = clocksource_default_clock();
if (clock->enable) if (clock->enable)
clock->enable(clock); clock->enable(clock);
@ -803,7 +808,8 @@ void __init timekeeping_init(void)
tmp.tv_nsec = 0; tmp.tv_nsec = 0;
tk_set_sleep_time(tk, tmp); 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 */ /* time in seconds when suspend began */
@ -851,7 +857,8 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
if (has_persistent_clock()) if (has_persistent_clock())
return; return;
write_seqlock_irqsave(&timekeeper_lock, flags); raw_spin_lock_irqsave(&timekeeper_lock, flags);
write_seqcount_begin(&timekeeper_seq);
timekeeping_forward_now(tk); timekeeping_forward_now(tk);
@ -859,7 +866,8 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
timekeeping_update(tk, true); 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 */ /* signal hrtimers about time change */
clock_was_set(); clock_was_set();
@ -886,7 +894,8 @@ static void timekeeping_resume(void)
clockevents_resume(); clockevents_resume();
clocksource_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 * After system resumes, we need to calculate the suspended time and
@ -938,7 +947,8 @@ static void timekeeping_resume(void)
tk->ntp_error = 0; tk->ntp_error = 0;
timekeeping_suspended = 0; timekeeping_suspended = 0;
timekeeping_update(tk, false); 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(); touch_softlockup_watchdog();
@ -957,7 +967,8 @@ static int timekeeping_suspend(void)
read_persistent_clock(&timekeeping_suspend_time); 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_forward_now(tk);
timekeeping_suspended = 1; timekeeping_suspended = 1;
@ -980,7 +991,8 @@ static int timekeeping_suspend(void)
timekeeping_suspend_time = timekeeping_suspend_time =
timespec_add(timekeeping_suspend_time, delta_delta); 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); clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
clocksource_suspend(); clocksource_suspend();
@ -1320,7 +1332,8 @@ static void update_wall_time(void)
int shift = 0, maxshift; int shift = 0, maxshift;
unsigned long flags; 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: */ /* Make sure we're fully resumed: */
if (unlikely(timekeeping_suspended)) if (unlikely(timekeeping_suspended))
@ -1375,7 +1388,8 @@ static void update_wall_time(void)
timekeeping_update(tk, false); timekeeping_update(tk, false);
out: 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); WARN_ON(timekeeping_suspended);
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
ts->tv_sec = tk->xtime_sec; ts->tv_sec = tk->xtime_sec;
nsec = timekeeping_get_ns(tk); nsec = timekeeping_get_ns(tk);
tomono = tk->wall_to_monotonic; tomono = tk->wall_to_monotonic;
sleep = tk->total_sleep_time; 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_sec += tomono.tv_sec + sleep.tv_sec;
ts->tv_nsec = 0; ts->tv_nsec = 0;
@ -1488,10 +1502,10 @@ struct timespec current_kernel_time(void)
unsigned long seq; unsigned long seq;
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
now = tk_xtime(tk); now = tk_xtime(tk);
} while (read_seqretry(&timekeeper_lock, seq)); } while (read_seqcount_retry(&timekeeper_seq, seq));
return now; return now;
} }
@ -1504,11 +1518,11 @@ struct timespec get_monotonic_coarse(void)
unsigned long seq; unsigned long seq;
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
now = tk_xtime(tk); now = tk_xtime(tk);
mono = tk->wall_to_monotonic; 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, set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
now.tv_nsec + mono.tv_nsec); now.tv_nsec + mono.tv_nsec);
@ -1539,11 +1553,11 @@ void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
unsigned long seq; unsigned long seq;
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
*xtim = tk_xtime(tk); *xtim = tk_xtime(tk);
*wtom = tk->wall_to_monotonic; *wtom = tk->wall_to_monotonic;
*sleep = tk->total_sleep_time; *sleep = tk->total_sleep_time;
} while (read_seqretry(&timekeeper_lock, seq)); } while (read_seqcount_retry(&timekeeper_seq, seq));
} }
#ifdef CONFIG_HIGH_RES_TIMERS #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; u64 secs, nsecs;
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
secs = tk->xtime_sec; secs = tk->xtime_sec;
nsecs = timekeeping_get_ns(tk); 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_real = tk->offs_real;
*offs_boot = tk->offs_boot; *offs_boot = tk->offs_boot;
*offs_tai = tk->offs_tai; *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_add_ns(ktime_set(secs, 0), nsecs);
now = ktime_sub(now, *offs_real); now = ktime_sub(now, *offs_real);
@ -1590,9 +1604,9 @@ ktime_t ktime_get_monotonic_offset(void)
struct timespec wtom; struct timespec wtom;
do { do {
seq = read_seqbegin(&timekeeper_lock); seq = read_seqcount_begin(&timekeeper_seq);
wtom = tk->wall_to_monotonic; wtom = tk->wall_to_monotonic;
} while (read_seqretry(&timekeeper_lock, seq)); } while (read_seqcount_retry(&timekeeper_seq, seq));
return timespec_to_ktime(wtom); return timespec_to_ktime(wtom);
} }