Jetpack/kernel/kernel-4.9/rt-patches/0048-timekeeping-Split-jiff...

171 lines
5.1 KiB
Diff

From e3e9f53f09f139bde8b9b9bb0f94e47f9bccaeb8 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 14 Feb 2013 22:36:59 +0100
Subject: [PATCH 048/352] timekeeping: Split jiffies seqlock
Replace jiffies_lock seqlock with a simple seqcounter and a rawlock so
it can be taken in atomic context on RT.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/time/jiffies.c | 7 ++++---
kernel/time/tick-common.c | 10 ++++++----
kernel/time/tick-sched.c | 19 ++++++++++++-------
kernel/time/timekeeping.c | 6 ++++--
kernel/time/timekeeping.h | 3 ++-
5 files changed, 28 insertions(+), 17 deletions(-)
diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c
index 2a6e41e..faea04a 100644
--- a/kernel/time/jiffies.c
+++ b/kernel/time/jiffies.c
@@ -74,7 +74,8 @@ static struct clocksource clocksource_jiffies = {
.max_cycles = 10,
};
-__cacheline_aligned_in_smp DEFINE_SEQLOCK(jiffies_lock);
+__cacheline_aligned_in_smp DEFINE_RAW_SPINLOCK(jiffies_lock);
+__cacheline_aligned_in_smp seqcount_t jiffies_seq;
#if (BITS_PER_LONG < 64)
u64 get_jiffies_64(void)
@@ -83,9 +84,9 @@ u64 get_jiffies_64(void)
u64 ret;
do {
- seq = read_seqbegin(&jiffies_lock);
+ seq = read_seqcount_begin(&jiffies_seq);
ret = jiffies_64;
- } while (read_seqretry(&jiffies_lock, seq));
+ } while (read_seqcount_retry(&jiffies_seq, seq));
return ret;
}
EXPORT_SYMBOL(get_jiffies_64);
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 4fcd99e..5a47f2e 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -79,13 +79,15 @@ int tick_is_oneshot_available(void)
static void tick_periodic(int cpu)
{
if (tick_do_timer_cpu == cpu) {
- write_seqlock(&jiffies_lock);
+ raw_spin_lock(&jiffies_lock);
+ write_seqcount_begin(&jiffies_seq);
/* Keep track of the next tick event */
tick_next_period = ktime_add(tick_next_period, tick_period);
do_timer(1);
- write_sequnlock(&jiffies_lock);
+ write_seqcount_end(&jiffies_seq);
+ raw_spin_unlock(&jiffies_lock);
update_wall_time();
}
@@ -157,9 +159,9 @@ void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
ktime_t next;
do {
- seq = read_seqbegin(&jiffies_lock);
+ seq = read_seqcount_begin(&jiffies_seq);
next = tick_next_period;
- } while (read_seqretry(&jiffies_lock, seq));
+ } while (read_seqcount_retry(&jiffies_seq, seq));
clockevents_switch_state(dev, CLOCK_EVT_STATE_ONESHOT);
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 65aafad..065f663 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -62,7 +62,8 @@ static void tick_do_update_jiffies64(ktime_t now)
return;
/* Reevaluate with jiffies_lock held */
- write_seqlock(&jiffies_lock);
+ raw_spin_lock(&jiffies_lock);
+ write_seqcount_begin(&jiffies_seq);
delta = ktime_sub(now, last_jiffies_update);
if (delta.tv64 >= tick_period.tv64) {
@@ -85,10 +86,12 @@ 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);
} else {
- write_sequnlock(&jiffies_lock);
+ write_seqcount_end(&jiffies_seq);
+ raw_spin_unlock(&jiffies_lock);
return;
}
- write_sequnlock(&jiffies_lock);
+ write_seqcount_end(&jiffies_seq);
+ raw_spin_unlock(&jiffies_lock);
update_wall_time();
}
@@ -99,12 +102,14 @@ static ktime_t tick_init_jiffy_update(void)
{
ktime_t period;
- write_seqlock(&jiffies_lock);
+ raw_spin_lock(&jiffies_lock);
+ write_seqcount_begin(&jiffies_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(&jiffies_lock);
+ write_seqcount_end(&jiffies_seq);
+ raw_spin_unlock(&jiffies_lock);
return period;
}
@@ -678,10 +683,10 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
/* Read jiffies and the time when jiffies were updated last */
do {
- seq = read_seqbegin(&jiffies_lock);
+ seq = read_seqcount_begin(&jiffies_seq);
basemono = last_jiffies_update.tv64;
basejiff = jiffies;
- } while (read_seqretry(&jiffies_lock, seq));
+ } while (read_seqcount_retry(&jiffies_seq, seq));
ts->last_jiffies = basejiff;
/*
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 831d3f0..07cfb84 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -2391,8 +2391,10 @@ EXPORT_SYMBOL(hardpps);
*/
void xtime_update(unsigned long ticks)
{
- write_seqlock(&jiffies_lock);
+ raw_spin_lock(&jiffies_lock);
+ write_seqcount_begin(&jiffies_seq);
do_timer(ticks);
- write_sequnlock(&jiffies_lock);
+ write_seqcount_end(&jiffies_seq);
+ raw_spin_unlock(&jiffies_lock);
update_wall_time();
}
diff --git a/kernel/time/timekeeping.h b/kernel/time/timekeeping.h
index 704f595..763a3e5 100644
--- a/kernel/time/timekeeping.h
+++ b/kernel/time/timekeeping.h
@@ -19,7 +19,8 @@ extern void timekeeping_resume(void);
extern void do_timer(unsigned long ticks);
extern void update_wall_time(void);
-extern seqlock_t jiffies_lock;
+extern raw_spinlock_t jiffies_lock;
+extern seqcount_t jiffies_seq;
#define CS_NAME_LEN 32
--
2.7.4