From f66aa661bcd8201092bd9e7f9f1c243627b42fe4 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 1 Mar 2012 15:14:06 +0100 Subject: [012/254] timekeeping: Split xtime_lock 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 --- kernel/time/jiffies.c | 4 +- kernel/time/tick-common.c | 10 ++-- kernel/time/tick-internal.h | 3 +- kernel/time/tick-sched.c | 16 +++--- kernel/time/timekeeping.c | 114 +++++++++++++++++++++++++------------------ 5 files changed, 87 insertions(+), 60 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/tick-common.c b/kernel/time/tick-common.c index da6c9ec..39de540 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 4e265b9..c91100d 100644 --- a/kernel/time/tick-internal.h +++ b/kernel/time/tick-internal.h @@ -141,4 +141,5 @@ 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 efd3866..a607a7c 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; } @@ -316,11 +320,11 @@ static void tick_nohz_stop_sched_tick(struct tick_sched *ts) 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 d66b213..56e151b 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -70,8 +70,9 @@ struct timekeeper { /* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */ struct timespec raw_time; - /* Seqlock for all timekeeper values */ - seqlock_t lock; + /* Open coded seqlock for all timekeeper values */ + seqcount_t seq; + raw_spinlock_t lock; }; static struct timekeeper timekeeper; @@ -80,7 +81,8 @@ static struct timekeeper timekeeper; * 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; /* flag for if timekeeping is suspended */ @@ -228,7 +230,7 @@ void getnstimeofday(struct timespec *ts) WARN_ON(timekeeping_suspended); do { - seq = read_seqbegin(&timekeeper.lock); + seq = read_seqcount_begin(&timekeeper.seq); *ts = timekeeper.xtime; nsecs = timekeeping_get_ns(); @@ -236,7 +238,7 @@ void getnstimeofday(struct timespec *ts) /* If arch requires, add in gettimeoffset() */ nsecs += arch_gettimeoffset(); - } while (read_seqretry(&timekeeper.lock, seq)); + } while (read_seqcount_retry(&timekeeper.seq, seq)); timespec_add_ns(ts, nsecs); } @@ -251,7 +253,7 @@ ktime_t ktime_get(void) WARN_ON(timekeeping_suspended); do { - seq = read_seqbegin(&timekeeper.lock); + seq = read_seqcount_begin(&timekeeper.seq); secs = timekeeper.xtime.tv_sec + timekeeper.wall_to_monotonic.tv_sec; nsecs = timekeeper.xtime.tv_nsec + @@ -260,7 +262,7 @@ ktime_t ktime_get(void) /* If arch requires, add in gettimeoffset() */ nsecs += arch_gettimeoffset(); - } 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. @@ -286,14 +288,14 @@ void ktime_get_ts(struct timespec *ts) WARN_ON(timekeeping_suspended); do { - seq = read_seqbegin(&timekeeper.lock); + seq = read_seqcount_begin(&timekeeper.seq); *ts = timekeeper.xtime; tomono = timekeeper.wall_to_monotonic; nsecs = timekeeping_get_ns(); /* If arch requires, add in gettimeoffset() */ nsecs += arch_gettimeoffset(); - } while (read_seqretry(&timekeeper.lock, seq)); + } while (read_seqcount_retry(&timekeeper.seq, seq)); set_normalized_timespec(ts, ts->tv_sec + tomono.tv_sec, ts->tv_nsec + tomono.tv_nsec + nsecs); @@ -321,7 +323,7 @@ void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real) do { u32 arch_offset; - seq = read_seqbegin(&timekeeper.lock); + seq = read_seqcount_begin(&timekeeper.seq); *ts_raw = timekeeper.raw_time; *ts_real = timekeeper.xtime; @@ -334,7 +336,7 @@ void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real) nsecs_raw += arch_offset; nsecs_real += arch_offset; - } while (read_seqretry(&timekeeper.lock, seq)); + } while (read_seqcount_retry(&timekeeper.seq, seq)); timespec_add_ns(ts_raw, nsecs_raw); timespec_add_ns(ts_real, nsecs_real); @@ -373,7 +375,8 @@ int do_settimeofday(const struct timespec *tv) if ((unsigned long)tv->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(); @@ -385,7 +388,8 @@ int do_settimeofday(const struct timespec *tv) timekeeper.xtime = *tv; timekeeping_update(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(); @@ -409,7 +413,8 @@ 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(); @@ -419,7 +424,8 @@ int timekeeping_inject_offset(struct timespec *ts) timekeeping_update(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(); @@ -440,7 +446,8 @@ 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(); if (!new->enable || new->enable(new) == 0) { @@ -451,7 +458,8 @@ static int change_clocksource(void *data) } timekeeping_update(true); - write_sequnlock_irqrestore(&timekeeper.lock, flags); + write_seqcount_end(&timekeeper.seq); + raw_spin_unlock_irqrestore(&timekeeper.lock, flags); return 0; } @@ -498,11 +506,11 @@ void getrawmonotonic(struct timespec *ts) s64 nsecs; do { - seq = read_seqbegin(&timekeeper.lock); + seq = read_seqcount_begin(&timekeeper.seq); nsecs = timekeeping_get_ns_raw(); *ts = timekeeper.raw_time; - } while (read_seqretry(&timekeeper.lock, seq)); + } while (read_seqcount_retry(&timekeeper.seq, seq)); timespec_add_ns(ts, nsecs); } @@ -518,11 +526,11 @@ int timekeeping_valid_for_hres(void) int ret; do { - seq = read_seqbegin(&timekeeper.lock); + seq = read_seqcount_begin(&timekeeper.seq); ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES; - } while (read_seqretry(&timekeeper.lock, seq)); + } while (read_seqcount_retry(&timekeeper.seq, seq)); return ret; } @@ -535,11 +543,11 @@ u64 timekeeping_max_deferment(void) unsigned long seq; u64 ret; do { - seq = read_seqbegin(&timekeeper.lock); + seq = read_seqcount_begin(&timekeeper.seq); ret = timekeeper.clock->max_idle_ns; - } while (read_seqretry(&timekeeper.lock, seq)); + } while (read_seqcount_retry(&timekeeper.seq, seq)); return ret; } @@ -586,11 +594,13 @@ void __init timekeeping_init(void) read_persistent_clock(&now); read_boot_clock(&boot); - seqlock_init(&timekeeper.lock); + raw_spin_lock_init(&timekeeper.lock); + seqcount_init(&timekeeper.seq); 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); @@ -608,7 +618,8 @@ void __init timekeeping_init(void) -boot.tv_sec, -boot.tv_nsec); timekeeper.total_sleep_time.tv_sec = 0; timekeeper.total_sleep_time.tv_nsec = 0; - write_sequnlock_irqrestore(&timekeeper.lock, flags); + write_seqcount_end(&timekeeper.seq); + raw_spin_unlock_irqrestore(&timekeeper.lock, flags); } /* time in seconds when suspend began */ @@ -657,7 +668,8 @@ void timekeeping_inject_sleeptime(struct timespec *delta) if (!(ts.tv_sec == 0 && ts.tv_nsec == 0)) return; - write_seqlock_irqsave(&timekeeper.lock, flags); + raw_spin_lock_irqsave(&timekeeper.lock, flags); + write_seqcount_begin(&timekeeper.seq); timekeeping_forward_now(); @@ -665,7 +677,8 @@ void timekeeping_inject_sleeptime(struct timespec *delta) timekeeping_update(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(); @@ -688,7 +701,8 @@ static void timekeeping_resume(void) clocksource_resume(); - write_seqlock_irqsave(&timekeeper.lock, flags); + raw_spin_lock_irqsave(&timekeeper.lock, flags); + write_seqcount_begin(&timekeeper.seq); if (timespec_compare(&ts, &timekeeping_suspend_time) > 0) { ts = timespec_sub(ts, timekeeping_suspend_time); @@ -698,7 +712,8 @@ static void timekeeping_resume(void) timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock); timekeeper.ntp_error = 0; timekeeping_suspended = 0; - write_sequnlock_irqrestore(&timekeeper.lock, flags); + write_seqcount_end(&timekeeper.seq); + raw_spin_unlock_irqrestore(&timekeeper.lock, flags); touch_softlockup_watchdog(); @@ -716,7 +731,8 @@ 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(); timekeeping_suspended = 1; @@ -739,7 +755,8 @@ 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(); @@ -997,7 +1014,8 @@ 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)) @@ -1084,8 +1102,8 @@ static void update_wall_time(void) timekeeping_update(false); out: - write_sequnlock_irqrestore(&timekeeper.lock, flags); - + write_seqcount_end(&timekeeper.seq); + raw_spin_unlock_irqrestore(&timekeeper.lock, flags); } /** @@ -1131,13 +1149,13 @@ void get_monotonic_boottime(struct timespec *ts) WARN_ON(timekeeping_suspended); do { - seq = read_seqbegin(&timekeeper.lock); + seq = read_seqcount_begin(&timekeeper.seq); *ts = timekeeper.xtime; tomono = timekeeper.wall_to_monotonic; sleep = timekeeper.total_sleep_time; nsecs = timekeeping_get_ns(); - } while (read_seqretry(&timekeeper.lock, seq)); + } while (read_seqcount_retry(&timekeeper.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); @@ -1188,10 +1206,10 @@ struct timespec current_kernel_time(void) unsigned long seq; do { - seq = read_seqbegin(&timekeeper.lock); + seq = read_seqcount_begin(&timekeeper.seq); now = timekeeper.xtime; - } while (read_seqretry(&timekeeper.lock, seq)); + } while (read_seqcount_retry(&timekeeper.seq, seq)); return now; } @@ -1203,11 +1221,11 @@ struct timespec get_monotonic_coarse(void) unsigned long seq; do { - seq = read_seqbegin(&timekeeper.lock); + seq = read_seqcount_begin(&timekeeper.seq); now = timekeeper.xtime; mono = timekeeper.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); @@ -1239,11 +1257,11 @@ 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 = timekeeper.xtime; *wtom = timekeeper.wall_to_monotonic; *sleep = timekeeper.total_sleep_time; - } while (read_seqretry(&timekeeper.lock, seq)); + } while (read_seqcount_retry(&timekeeper.seq, seq)); } /** @@ -1255,9 +1273,9 @@ ktime_t ktime_get_monotonic_offset(void) struct timespec wtom; do { - seq = read_seqbegin(&timekeeper.lock); + seq = read_seqcount_begin(&timekeeper.seq); wtom = timekeeper.wall_to_monotonic; - } while (read_seqretry(&timekeeper.lock, seq)); + } while (read_seqcount_retry(&timekeeper.seq, seq)); return timespec_to_ktime(wtom); } @@ -1272,7 +1290,9 @@ EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset); */ 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); }