175 lines
5.6 KiB
Diff
175 lines
5.6 KiB
Diff
From c7b1c3d119e7b79eff59e2e1d7ad37e563dfd44d Mon Sep 17 00:00:00 2001
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Message-Id: <c7b1c3d119e7b79eff59e2e1d7ad37e563dfd44d.1596234183.git.zanussi@kernel.org>
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In-Reply-To: <378ee68279f6a7631221f2670a9298620148690d.1596234183.git.zanussi@kernel.org>
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References: <378ee68279f6a7631221f2670a9298620148690d.1596234183.git.zanussi@kernel.org>
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Thu, 14 Feb 2013 22:36:59 +0100
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Subject: [PATCH 031/329] timekeeping: Split jiffies seqlock
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.135-rt60.tar.xz
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Replace jiffies_lock seqlock with a simple seqcounter and a rawlock so
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it can be taken in atomic context on RT.
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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kernel/time/jiffies.c | 7 ++++---
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kernel/time/tick-common.c | 10 ++++++----
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kernel/time/tick-sched.c | 19 ++++++++++++-------
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kernel/time/timekeeping.c | 6 ++++--
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kernel/time/timekeeping.h | 3 ++-
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5 files changed, 28 insertions(+), 17 deletions(-)
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diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c
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index 497719127bf9..62acb8914c9e 100644
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--- a/kernel/time/jiffies.c
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+++ b/kernel/time/jiffies.c
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@@ -74,7 +74,8 @@ static struct clocksource clocksource_jiffies = {
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.max_cycles = 10,
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};
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-__cacheline_aligned_in_smp DEFINE_SEQLOCK(jiffies_lock);
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+__cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(jiffies_lock);
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+__cacheline_aligned_in_smp seqcount_t jiffies_seq;
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#if (BITS_PER_LONG < 64)
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u64 get_jiffies_64(void)
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@@ -83,9 +84,9 @@ u64 get_jiffies_64(void)
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u64 ret;
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do {
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- seq = read_seqbegin(&jiffies_lock);
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+ seq = read_seqcount_begin(&jiffies_seq);
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ret = jiffies_64;
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- } while (read_seqretry(&jiffies_lock, seq));
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+ } while (read_seqcount_retry(&jiffies_seq, seq));
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return ret;
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}
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EXPORT_SYMBOL(get_jiffies_64);
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diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
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index a02e0f6b287c..32f5101f07ce 100644
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--- a/kernel/time/tick-common.c
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+++ b/kernel/time/tick-common.c
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@@ -79,13 +79,15 @@ int tick_is_oneshot_available(void)
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static void tick_periodic(int cpu)
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{
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if (tick_do_timer_cpu == cpu) {
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- write_seqlock(&jiffies_lock);
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+ raw_spin_lock(&jiffies_lock);
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+ write_seqcount_begin(&jiffies_seq);
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/* Keep track of the next tick event */
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tick_next_period = ktime_add(tick_next_period, tick_period);
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do_timer(1);
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- write_sequnlock(&jiffies_lock);
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+ write_seqcount_end(&jiffies_seq);
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+ raw_spin_unlock(&jiffies_lock);
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update_wall_time();
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}
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@@ -157,9 +159,9 @@ void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
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ktime_t next;
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do {
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- seq = read_seqbegin(&jiffies_lock);
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+ seq = read_seqcount_begin(&jiffies_seq);
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next = tick_next_period;
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- } while (read_seqretry(&jiffies_lock, seq));
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+ } while (read_seqcount_retry(&jiffies_seq, seq));
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clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
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diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
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index 48403fb653c2..e774a49176cc 100644
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--- a/kernel/time/tick-sched.c
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+++ b/kernel/time/tick-sched.c
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@@ -68,7 +68,8 @@ static void tick_do_update_jiffies64(ktime_t now)
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return;
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/* Reevaluate with jiffies_lock held */
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- write_seqlock(&jiffies_lock);
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+ raw_spin_lock(&jiffies_lock);
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+ write_seqcount_begin(&jiffies_seq);
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delta = ktime_sub(now, last_jiffies_update);
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if (delta >= tick_period) {
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@@ -94,10 +95,12 @@ static void tick_do_update_jiffies64(ktime_t now)
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/* Keep the tick_next_period variable up to date */
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tick_next_period = ktime_add(last_jiffies_update, tick_period);
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} else {
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- write_sequnlock(&jiffies_lock);
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+ write_seqcount_end(&jiffies_seq);
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+ raw_spin_unlock(&jiffies_lock);
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return;
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}
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- write_sequnlock(&jiffies_lock);
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+ write_seqcount_end(&jiffies_seq);
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+ raw_spin_unlock(&jiffies_lock);
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update_wall_time();
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}
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@@ -108,12 +111,14 @@ static ktime_t tick_init_jiffy_update(void)
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{
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ktime_t period;
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- write_seqlock(&jiffies_lock);
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+ raw_spin_lock(&jiffies_lock);
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+ write_seqcount_begin(&jiffies_seq);
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/* Did we start the jiffies update yet ? */
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if (last_jiffies_update == 0)
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last_jiffies_update = tick_next_period;
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period = last_jiffies_update;
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- write_sequnlock(&jiffies_lock);
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+ write_seqcount_end(&jiffies_seq);
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+ raw_spin_unlock(&jiffies_lock);
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return period;
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}
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@@ -656,10 +661,10 @@ static ktime_t tick_nohz_next_event(struct tick_sched *ts, int cpu)
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/* Read jiffies and the time when jiffies were updated last */
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do {
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- seq = read_seqbegin(&jiffies_lock);
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+ seq = read_seqcount_begin(&jiffies_seq);
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basemono = last_jiffies_update;
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basejiff = jiffies;
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- } while (read_seqretry(&jiffies_lock, seq));
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+ } while (read_seqcount_retry(&jiffies_seq, seq));
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ts->last_jiffies = basejiff;
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ts->timer_expires_base = basemono;
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diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
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index 81ee5b83c920..512db778f442 100644
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--- a/kernel/time/timekeeping.c
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+++ b/kernel/time/timekeeping.c
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@@ -2394,8 +2394,10 @@ EXPORT_SYMBOL(hardpps);
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*/
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void xtime_update(unsigned long ticks)
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{
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- write_seqlock(&jiffies_lock);
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+ raw_spin_lock(&jiffies_lock);
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+ write_seqcount_begin(&jiffies_seq);
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do_timer(ticks);
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- write_sequnlock(&jiffies_lock);
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+ write_seqcount_end(&jiffies_seq);
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+ raw_spin_unlock(&jiffies_lock);
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update_wall_time();
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}
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diff --git a/kernel/time/timekeeping.h b/kernel/time/timekeeping.h
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index 141ab3ab0354..099737f6f10c 100644
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--- a/kernel/time/timekeeping.h
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+++ b/kernel/time/timekeeping.h
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@@ -25,7 +25,8 @@ static inline void sched_clock_resume(void) { }
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extern void do_timer(unsigned long ticks);
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extern void update_wall_time(void);
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-extern seqlock_t jiffies_lock;
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+extern raw_spinlock_t jiffies_lock;
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+extern seqcount_t jiffies_seq;
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#define CS_NAME_LEN 32
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--
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2.17.1
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