From 9a7a71b1d0968fc2bd602b7481cde1d4872e01ff Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 21 Feb 2013 22:51:38 +0000 Subject: [PATCH] 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 [jstultz: Merge fixups from CLOCK_TAI collisions] Signed-off-by: John Stultz --- kernel/time/timekeeping.c | 132 +++++++++++++++++++++----------------- 1 file changed, 73 insertions(+), 59 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index caede71c0a35..5e048e030c62 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); }