[PATCH RT 15/25][RFC 3.0.23-rt39-rc1] timekeeping: Split xtime_lock

Steven Rostedt
2012-03-06T16:19:54Z

[-- Attachment #1: 0015-timekeeping-Split-xtime_lock.patch --]
[-- Type: text/plain, Size: 16629 bytes --]

From: Thomas Gleixner <tglx@linutronix.de>

xtime_lock is going to be split apart in mainline, so we can shorten
the seqcount protected regions and avoid updating seqcount in some
code pathes. This is a straight forward split, so we can avoid the
whole mess with raw seqlocks for RT.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable-rt@vger.kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/time/jiffies.c | 4 +-
kernel/time/ntp.c | 24 ++++++++----
kernel/time/tick-common.c | 10 +++--
kernel/time/tick-internal.h | 3 +-
kernel/time/tick-sched.c | 16 +++++---
kernel/time/timekeeping.c | 90 +++++++++++++++++++++++++------------------
6 files changed, 88 insertions(+), 59 deletions(-)

diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c
index a470154..21940eb 100644
--- a/kernel/time/jiffies.c
+++ b/kernel/time/jiffies.c
@@ -74,9 +74,9 @@ u64 get_jiffies_64(void)
u64 ret;

do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqcount_begin(&xtime_seq);
ret = jiffies_64;
- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqcount_retry(&xtime_seq, seq));
return ret;
}
EXPORT_SYMBOL(get_jiffies_64);
diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index f6117a4..c465e88 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -358,7 +358,8 @@ static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer)
{
enum hrtimer_restart res = HRTIMER_NORESTART;

- write_seqlock(&xtime_lock);
+ raw_spin_lock(&xtime_lock);
+ write_seqcount_begin(&xtime_seq);

switch (time_state) {
case TIME_OK:
@@ -388,7 +389,8 @@ static enum hrtimer_restart ntp_leap_second(struct hrtimer *timer)
break;
}

- write_sequnlock(&xtime_lock);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock(&xtime_lock);

return res;
}
@@ -663,7 +665,8 @@ int do_adjtimex(struct timex *txc)

getnstimeofday(&ts);

- write_seqlock_irq(&xtime_lock);
+ raw_spin_lock_irq(&xtime_lock);
+ write_seqcount_begin(&xtime_seq);

if (txc->modes & ADJ_ADJTIME) {
long save_adjust = time_adjust;
@@ -705,7 +708,8 @@ int do_adjtimex(struct timex *txc)
/* fill PPS status fields */
pps_fill_timex(txc);

- write_sequnlock_irq(&xtime_lock);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock_irq(&xtime_lock);

txc->time.tv_sec = ts.tv_sec;
txc->time.tv_usec = ts.tv_nsec;
@@ -903,7 +907,8 @@ void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts)

pts_norm = pps_normalize_ts(*phase_ts);

- write_seqlock_irqsave(&xtime_lock, flags);
+ raw_spin_lock_irqsave(&xtime_lock, flags);
+ write_seqcount_begin(&xtime_seq);

/* clear the error bits, they will be set again if needed */
time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
@@ -916,7 +921,8 @@ void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts)
* just start the frequency interval */
if (unlikely(pps_fbase.tv_sec == 0)) {
pps_fbase = *raw_ts;
- write_sequnlock_irqrestore(&xtime_lock, flags);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock_irqrestore(&xtime_lock, flags);
return;
}

@@ -931,7 +937,8 @@ void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts)
time_status |= STA_PPSJITTER;
/* restart the frequency calibration interval */
pps_fbase = *raw_ts;
- write_sequnlock_irqrestore(&xtime_lock, flags);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock_irqrestore(&xtime_lock, flags);
pr_err("hardpps: PPSJITTER: bad pulse\n");
return;
}
@@ -948,7 +955,8 @@ void hardpps(const struct timespec *phase_ts, const struct timespec *raw_ts)

hardpps_update_phase(pts_norm.nsec);

- write_sequnlock_irqrestore(&xtime_lock, flags);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock_irqrestore(&xtime_lock, flags);
}
EXPORT_SYMBOL(hardpps);

diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 119528d..25fb6ad 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -63,13 +63,15 @@ int tick_is_oneshot_available(void)
static void tick_periodic(int cpu)
{
if (tick_do_timer_cpu == cpu) {
- write_seqlock(&xtime_lock);
+ raw_spin_lock(&xtime_lock);
+ write_seqcount_begin(&xtime_seq);

/* Keep track of the next tick event */
tick_next_period = ktime_add(tick_next_period, tick_period);

do_timer(1);
- write_sequnlock(&xtime_lock);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock(&xtime_lock);
}

update_process_times(user_mode(get_irq_regs()));
@@ -130,9 +132,9 @@ void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
ktime_t next;

do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqcount_begin(&xtime_seq);
next = tick_next_period;
- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqcount_retry(&xtime_seq, seq));

clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);

diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 1009b06..116e861 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -143,4 +143,5 @@ static inline int tick_device_is_functional(struct clock_event_device *dev)
#endif

extern void do_timer(unsigned long ticks);
-extern seqlock_t xtime_lock;
+extern raw_spinlock_t xtime_lock;
+extern seqcount_t xtime_seq;
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 2a6e13c..5f620b0 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -56,7 +56,8 @@ static void tick_do_update_jiffies64(ktime_t now)
return;

/* Reevalute with xtime_lock held */
- write_seqlock(&xtime_lock);
+ raw_spin_lock(&xtime_lock);
+ write_seqcount_begin(&xtime_seq);

delta = ktime_sub(now, last_jiffies_update);
if (delta.tv64 >= tick_period.tv64) {
@@ -79,7 +80,8 @@ static void tick_do_update_jiffies64(ktime_t now)
/* Keep the tick_next_period variable up to date */
tick_next_period = ktime_add(last_jiffies_update, tick_period);
}
- write_sequnlock(&xtime_lock);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock(&xtime_lock);
}

/*
@@ -89,12 +91,14 @@ static ktime_t tick_init_jiffy_update(void)
{
ktime_t period;

- write_seqlock(&xtime_lock);
+ raw_spin_lock(&xtime_lock);
+ write_seqcount_begin(&xtime_seq);
/* Did we start the jiffies update yet ? */
if (last_jiffies_update.tv64 == 0)
last_jiffies_update = tick_next_period;
period = last_jiffies_update;
- write_sequnlock(&xtime_lock);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock(&xtime_lock);
return period;
}

@@ -311,11 +315,11 @@ void tick_nohz_stop_sched_tick(int inidle)
ts->idle_calls++;
/* Read jiffies and the time when jiffies were updated last */
do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqcount_begin(&xtime_seq);
last_update = last_jiffies_update;
last_jiffies = jiffies;
time_delta = timekeeping_max_deferment();
- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqcount_retry(&xtime_seq, seq));

if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) ||
arch_needs_cpu(cpu)) {
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 5f45831..6ac6438 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -139,8 +139,8 @@ static inline s64 timekeeping_get_ns_raw(void)
* This read-write spinlock protects us from races in SMP while
* playing with xtime.
*/
-__cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
-
+__cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(xtime_lock);
+seqcount_t xtime_seq;

/*
* The current time
@@ -222,7 +222,7 @@ void getnstimeofday(struct timespec *ts)
WARN_ON(timekeeping_suspended);

do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqcount_begin(&xtime_seq);

*ts = xtime;
nsecs = timekeeping_get_ns();
@@ -230,7 +230,7 @@ void getnstimeofday(struct timespec *ts)
/* If arch requires, add in gettimeoffset() */
nsecs += arch_gettimeoffset();

- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqcount_retry(&xtime_seq, seq));

timespec_add_ns(ts, nsecs);
}
@@ -245,14 +245,14 @@ ktime_t ktime_get(void)
WARN_ON(timekeeping_suspended);

do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqcount_begin(&xtime_seq);
secs = xtime.tv_sec + wall_to_monotonic.tv_sec;
nsecs = xtime.tv_nsec + wall_to_monotonic.tv_nsec;
nsecs += timekeeping_get_ns();
/* If arch requires, add in gettimeoffset() */
nsecs += arch_gettimeoffset();

- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqcount_retry(&xtime_seq, seq));
/*
* Use ktime_set/ktime_add_ns to create a proper ktime on
* 32-bit architectures without CONFIG_KTIME_SCALAR.
@@ -278,14 +278,14 @@ void ktime_get_ts(struct timespec *ts)
WARN_ON(timekeeping_suspended);

do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqcount_begin(&xtime_seq);
*ts = xtime;
tomono = wall_to_monotonic;
nsecs = timekeeping_get_ns();
/* If arch requires, add in gettimeoffset() */
nsecs += arch_gettimeoffset();

- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqcount_retry(&xtime_seq, seq));

set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec,
ts->tv_nsec + tomono.tv_nsec + nsecs);
@@ -313,7 +313,7 @@ void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
do {
u32 arch_offset;

- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqcount_begin(&xtime_seq);

*ts_raw = raw_time;
*ts_real = xtime;
@@ -326,7 +326,7 @@ void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
nsecs_raw += arch_offset;
nsecs_real += arch_offset;

- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqcount_retry(&xtime_seq, seq));

timespec_add_ns(ts_raw, nsecs_raw);
timespec_add_ns(ts_real, nsecs_real);
@@ -365,7 +365,8 @@ int do_settimeofday(const struct timespec *tv)
if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;

- write_seqlock_irqsave(&xtime_lock, flags);
+ raw_spin_lock_irqsave(&xtime_lock, flags);
+ write_seqcount_begin(&xtime_seq);

timekeeping_forward_now();

@@ -381,7 +382,8 @@ int do_settimeofday(const struct timespec *tv)
update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
timekeeper.mult);

- write_sequnlock_irqrestore(&xtime_lock, flags);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock_irqrestore(&xtime_lock, flags);

/* signal hrtimers about time change */
clock_was_set();
@@ -405,7 +407,8 @@ int timekeeping_inject_offset(struct timespec *ts)
if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;

- write_seqlock_irqsave(&xtime_lock, flags);
+ raw_spin_lock_irqsave(&xtime_lock, flags);
+ write_seqcount_begin(&xtime_seq);

timekeeping_forward_now();

@@ -418,7 +421,8 @@ int timekeeping_inject_offset(struct timespec *ts)
update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
timekeeper.mult);

- write_sequnlock_irqrestore(&xtime_lock, flags);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock_irqrestore(&xtime_lock, flags);

/* signal hrtimers about time change */
clock_was_set();
@@ -490,11 +494,11 @@ void getrawmonotonic(struct timespec *ts)
s64 nsecs;

do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqcount_begin(&xtime_seq);
nsecs = timekeeping_get_ns_raw();
*ts = raw_time;

- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqcount_retry(&xtime_seq, seq));

timespec_add_ns(ts, nsecs);
}
@@ -510,11 +514,11 @@ int timekeeping_valid_for_hres(void)
int ret;

do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqcount_begin(&xtime_seq);

ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;

- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqcount_retry(&xtime_seq, seq));

return ret;
}
@@ -572,7 +576,8 @@ void __init timekeeping_init(void)
read_persistent_clock(&now);
read_boot_clock(&boot);

- write_seqlock_irqsave(&xtime_lock, flags);
+ raw_spin_lock_irqsave(&xtime_lock, flags);
+ write_seqcount_begin(&xtime_seq);

ntp_init();

@@ -593,7 +598,8 @@ void __init timekeeping_init(void)
-boot.tv_sec, -boot.tv_nsec);
total_sleep_time.tv_sec = 0;
total_sleep_time.tv_nsec = 0;
- write_sequnlock_irqrestore(&xtime_lock, flags);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock_irqrestore(&xtime_lock, flags);
}

/* time in seconds when suspend began */
@@ -634,7 +640,8 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
if (!(ts.tv_sec == 0 && ts.tv_nsec == 0))
return;

- write_seqlock_irqsave(&xtime_lock, flags);
+ raw_spin_lock_irqsave(&xtime_lock, flags);
+ write_seqcount_begin(&xtime_seq);
timekeeping_forward_now();

__timekeeping_inject_sleeptime(delta);
@@ -644,7 +651,8 @@ void timekeeping_inject_sleeptime(struct timespec *delta)
update_vsyscall(&xtime, &wall_to_monotonic, timekeeper.clock,
timekeeper.mult);

- write_sequnlock_irqrestore(&xtime_lock, flags);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock_irqrestore(&xtime_lock, flags);

/* signal hrtimers about time change */
clock_was_set();
@@ -667,7 +675,8 @@ static void timekeeping_resume(void)

clocksource_resume();

- write_seqlock_irqsave(&xtime_lock, flags);
+ raw_spin_lock_irqsave(&xtime_lock, flags);
+ write_seqcount_begin(&xtime_seq);

if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) {
ts = timespec_sub(ts, timekeeping_suspend_time);
@@ -677,7 +686,8 @@ static void timekeeping_resume(void)
timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
timekeeper.ntp_error = 0;
timekeeping_suspended = 0;
- write_sequnlock_irqrestore(&xtime_lock, flags);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock_irqrestore(&xtime_lock, flags);

touch_softlockup_watchdog();

@@ -693,10 +703,12 @@ static int timekeeping_suspend(void)

read_persistent_clock(&timekeeping_suspend_time);

- write_seqlock_irqsave(&xtime_lock, flags);
+ raw_spin_lock_irqsave(&xtime_lock, flags);
+ write_seqcount_begin(&xtime_seq);
timekeeping_forward_now();
timekeeping_suspended = 1;
- write_sequnlock_irqrestore(&xtime_lock, flags);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock_irqrestore(&xtime_lock, flags);

clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
clocksource_suspend();
@@ -987,13 +999,13 @@ void get_monotonic_boottime(struct timespec *ts)
WARN_ON(timekeeping_suspended);

do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqcount_begin(&xtime_seq);
*ts = xtime;
tomono = wall_to_monotonic;
sleep = total_sleep_time;
nsecs = timekeeping_get_ns();

- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqcount_retry(&xtime_seq, seq));

set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec + sleep.tv_sec,
ts->tv_nsec + tomono.tv_nsec + sleep.tv_nsec + nsecs);
@@ -1044,10 +1056,10 @@ struct timespec current_kernel_time(void)
unsigned long seq;

do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqcount_begin(&xtime_seq);

now = xtime;
- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqcount_retry(&xtime_seq, seq));

return now;
}
@@ -1059,11 +1071,11 @@ struct timespec get_monotonic_coarse(void)
unsigned long seq;

do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqcount_begin(&xtime_seq);

now = xtime;
mono = wall_to_monotonic;
- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqcount_retry(&xtime_seq, seq));

set_normalized_timespec(&now, now.tv_sec + mono.tv_sec,
now.tv_nsec + mono.tv_nsec);
@@ -1095,11 +1107,11 @@ void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
unsigned long seq;

do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqcount_begin(&xtime_seq);
*xtim = xtime;
*wtom = wall_to_monotonic;
*sleep = total_sleep_time;
- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqcount_retry(&xtime_seq, seq));
}

/**
@@ -1111,9 +1123,9 @@ ktime_t ktime_get_monotonic_offset(void)
struct timespec wtom;

do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqcount_begin(&xtime_seq);
wtom = wall_to_monotonic;
- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqcount_retry(&xtime_seq, seq));
return timespec_to_ktime(wtom);
}

@@ -1125,7 +1137,9 @@ ktime_t ktime_get_monotonic_offset(void)
*/
void xtime_update(unsigned long ticks)
{
- write_seqlock(&xtime_lock);
+ raw_spin_lock(&xtime_lock);
+ write_seqcount_begin(&xtime_seq);
do_timer(ticks);
- write_sequnlock(&xtime_lock);
+ write_seqcount_end(&xtime_seq);
+ raw_spin_unlock(&xtime_lock);
}
--
1.7.8.3