[GIT PULL] timers/core changes for v3.8

From: Ingo Molnar
Date: Tue Dec 11 2012 - 04:46:56 EST

Linus,

Please pull the latest timers-core-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers-core-for-linus

HEAD: 9c3f9e281697d02889c3b08922f3b30be75f56c2 Merge branch 'fortglx/3.8/time' of git://git.linaro.org/people/jstultz/linux into timers/core

It contains continued generic-NOHZ work by Frederic and smaller
cleanups.

Thanks,

Ingo

------------------>
Chuansheng Liu (1):
tick: Correct the comments for tick_sched_timer()

Dan Carpenter (1):
clocksource: clean up parse_pmtmr()

Frederic Weisbecker (3):
tick: Consolidate timekeeping handling code
tick: Consolidate tick handling for high and low res handlers
tick: Conditionally build nohz specific code in tick handler

John Stultz (1):
time: Kill xtime_lock, replacing it with jiffies_lock

Lars-Peter Clausen (1):
time/jiffies: Make clocksource_jiffies static

Linus Walleij (1):
clocksource: arm_generic: use integer math helpers

Shan Wei (1):
clocksource: arm_generic: use this_cpu_ptr per-cpu helper


drivers/clocksource/acpi_pm.c | 17 +++--
drivers/clocksource/arm_generic.c | 6 +-
drivers/clocksource/i8253.c | 2 +-
include/linux/jiffies.h | 3 +-
kernel/time/jiffies.c | 8 ++-
kernel/time/tick-common.c | 8 +--
kernel/time/tick-internal.h | 1 -
kernel/time/tick-sched.c | 133 +++++++++++++++++---------------------
kernel/time/timekeeping.c | 14 +---
9 files changed, 85 insertions(+), 107 deletions(-)

diff --git a/drivers/clocksource/acpi_pm.c b/drivers/clocksource/acpi_pm.c
index 6b5cf02..5d1b926 100644
--- a/drivers/clocksource/acpi_pm.c
+++ b/drivers/clocksource/acpi_pm.c
@@ -233,16 +233,15 @@ fs_initcall(init_acpi_pm_clocksource);
*/
static int __init parse_pmtmr(char *arg)
{
- unsigned long base;
+ unsigned int base;
+ int ret;

- if (strict_strtoul(arg, 16, &base))
- return -EINVAL;
-#ifdef CONFIG_X86_64
- if (base > UINT_MAX)
- return -ERANGE;
-#endif
- printk(KERN_INFO "PMTMR IOPort override: 0x%04x -> 0x%04lx\n",
- pmtmr_ioport, base);
+ ret = kstrtouint(arg, 16, &base);
+ if (ret)
+ return ret;
+
+ pr_info("PMTMR IOPort override: 0x%04x -> 0x%04x\n", pmtmr_ioport,
+ base);
pmtmr_ioport = base;

return 1;
diff --git a/drivers/clocksource/arm_generic.c b/drivers/clocksource/arm_generic.c
index c4d9f95..c210f4f 100644
--- a/drivers/clocksource/arm_generic.c
+++ b/drivers/clocksource/arm_generic.c
@@ -127,7 +127,7 @@ static void __init arch_timer_calibrate(void)

/* Cache the sched_clock multiplier to save a divide in the hot path. */

- sched_clock_mult = NSEC_PER_SEC / arch_timer_rate;
+ sched_clock_mult = DIV_ROUND_CLOSEST(NSEC_PER_SEC, arch_timer_rate);

pr_info("Architected local timer running at %u.%02uMHz.\n",
arch_timer_rate / 1000000, (arch_timer_rate / 10000) % 100);
@@ -221,10 +221,10 @@ int __init arm_generic_timer_init(void)
clocksource_register_hz(&clocksource_counter, arch_timer_rate);

/* Calibrate the delay loop directly */
- lpj_fine = arch_timer_rate / HZ;
+ lpj_fine = DIV_ROUND_CLOSEST(arch_timer_rate, HZ);

/* Immediately configure the timer on the boot CPU */
- arch_timer_setup(per_cpu_ptr(&arch_timer_evt, smp_processor_id()));
+ arch_timer_setup(this_cpu_ptr(&arch_timer_evt));

register_cpu_notifier(&arch_timer_cpu_nb);

diff --git a/drivers/clocksource/i8253.c b/drivers/clocksource/i8253.c
index e7cab2d..14ee3ef 100644
--- a/drivers/clocksource/i8253.c
+++ b/drivers/clocksource/i8253.c
@@ -35,7 +35,7 @@ static cycle_t i8253_read(struct clocksource *cs)

raw_spin_lock_irqsave(&i8253_lock, flags);
/*
- * Although our caller may have the read side of xtime_lock,
+ * Although our caller may have the read side of jiffies_lock,
* this is now a seqlock, and we are cheating in this routine
* by having side effects on state that we cannot undo if
* there is a collision on the seqlock and our caller has to
diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h
index 6b87413..82ed068 100644
--- a/include/linux/jiffies.h
+++ b/include/linux/jiffies.h
@@ -70,11 +70,12 @@ extern int register_refined_jiffies(long clock_tick_rate);

/*
* The 64-bit value is not atomic - you MUST NOT read it
- * without sampling the sequence number in xtime_lock.
+ * without sampling the sequence number in jiffies_lock.
* get_jiffies_64() will do this for you as appropriate.
*/
extern u64 __jiffy_data jiffies_64;
extern unsigned long volatile __jiffy_data jiffies;
+extern seqlock_t jiffies_lock;

#if (BITS_PER_LONG < 64)
u64 get_jiffies_64(void);
diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c
index 6629bf7..7a925ba 100644
--- a/kernel/time/jiffies.c
+++ b/kernel/time/jiffies.c
@@ -58,7 +58,7 @@ static cycle_t jiffies_read(struct clocksource *cs)
return (cycle_t) jiffies;
}

-struct clocksource clocksource_jiffies = {
+static struct clocksource clocksource_jiffies = {
.name = "jiffies",
.rating = 1, /* lowest valid rating*/
.read = jiffies_read,
@@ -67,6 +67,8 @@ struct clocksource clocksource_jiffies = {
.shift = JIFFIES_SHIFT,
};

+__cacheline_aligned_in_smp DEFINE_SEQLOCK(jiffies_lock);
+
#if (BITS_PER_LONG < 64)
u64 get_jiffies_64(void)
{
@@ -74,9 +76,9 @@ u64 get_jiffies_64(void)
u64 ret;

do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqbegin(&jiffies_lock);
ret = jiffies_64;
- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqretry(&jiffies_lock, seq));
return ret;
}
EXPORT_SYMBOL(get_jiffies_64);
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index da6c9ec..b1600a6 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -63,13 +63,13 @@ int tick_is_oneshot_available(void)
static void tick_periodic(int cpu)
{
if (tick_do_timer_cpu == cpu) {
- write_seqlock(&xtime_lock);
+ write_seqlock(&jiffies_lock);

/* 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_sequnlock(&jiffies_lock);
}

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

do {
- seq = read_seqbegin(&xtime_lock);
+ seq = read_seqbegin(&jiffies_lock);
next = tick_next_period;
- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqretry(&jiffies_lock, 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..cf3e59e 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -141,4 +141,3 @@ 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;
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index a402608..c96fd6a 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -31,7 +31,7 @@
static DEFINE_PER_CPU(struct tick_sched, tick_cpu_sched);

/*
- * The time, when the last jiffy update happened. Protected by xtime_lock.
+ * The time, when the last jiffy update happened. Protected by jiffies_lock.
*/
static ktime_t last_jiffies_update;

@@ -49,14 +49,14 @@ static void tick_do_update_jiffies64(ktime_t now)
ktime_t delta;

/*
- * Do a quick check without holding xtime_lock:
+ * Do a quick check without holding jiffies_lock:
*/
delta = ktime_sub(now, last_jiffies_update);
if (delta.tv64 < tick_period.tv64)
return;

- /* Reevalute with xtime_lock held */
- write_seqlock(&xtime_lock);
+ /* Reevalute with jiffies_lock held */
+ write_seqlock(&jiffies_lock);

delta = ktime_sub(now, last_jiffies_update);
if (delta.tv64 >= tick_period.tv64) {
@@ -79,7 +79,7 @@ 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_sequnlock(&jiffies_lock);
}

/*
@@ -89,15 +89,58 @@ static ktime_t tick_init_jiffy_update(void)
{
ktime_t period;

- write_seqlock(&xtime_lock);
+ write_seqlock(&jiffies_lock);
/* 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_sequnlock(&jiffies_lock);
return period;
}

+
+static void tick_sched_do_timer(ktime_t now)
+{
+ int cpu = smp_processor_id();
+
+#ifdef CONFIG_NO_HZ
+ /*
+ * Check if the do_timer duty was dropped. We don't care about
+ * concurrency: This happens only when the cpu in charge went
+ * into a long sleep. If two cpus happen to assign themself to
+ * this duty, then the jiffies update is still serialized by
+ * jiffies_lock.
+ */
+ if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
+ tick_do_timer_cpu = cpu;
+#endif
+
+ /* Check, if the jiffies need an update */
+ if (tick_do_timer_cpu == cpu)
+ tick_do_update_jiffies64(now);
+}
+
+static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs)
+{
+#ifdef CONFIG_NO_HZ
+ /*
+ * When we are idle and the tick is stopped, we have to touch
+ * the watchdog as we might not schedule for a really long
+ * time. This happens on complete idle SMP systems while
+ * waiting on the login prompt. We also increment the "start of
+ * idle" jiffy stamp so the idle accounting adjustment we do
+ * when we go busy again does not account too much ticks.
+ */
+ if (ts->tick_stopped) {
+ touch_softlockup_watchdog();
+ if (is_idle_task(current))
+ ts->idle_jiffies++;
+ }
+#endif
+ update_process_times(user_mode(regs));
+ profile_tick(CPU_PROFILING);
+}
+
/*
* NOHZ - aka dynamic tick functionality
*/
@@ -282,11 +325,11 @@ 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(&xtime_lock);
+ seq = read_seqbegin(&jiffies_lock);
last_update = last_jiffies_update;
last_jiffies = jiffies;
time_delta = timekeeping_max_deferment();
- } while (read_seqretry(&xtime_lock, seq));
+ } while (read_seqretry(&jiffies_lock, seq));

if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) || printk_needs_cpu(cpu) ||
arch_needs_cpu(cpu)) {
@@ -648,40 +691,12 @@ static void tick_nohz_handler(struct clock_event_device *dev)
{
struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
struct pt_regs *regs = get_irq_regs();
- int cpu = smp_processor_id();
ktime_t now = ktime_get();

dev->next_event.tv64 = KTIME_MAX;

- /*
- * Check if the do_timer duty was dropped. We don't care about
- * concurrency: This happens only when the cpu in charge went
- * into a long sleep. If two cpus happen to assign themself to
- * this duty, then the jiffies update is still serialized by
- * xtime_lock.
- */
- if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
- tick_do_timer_cpu = cpu;
-
- /* Check, if the jiffies need an update */
- if (tick_do_timer_cpu == cpu)
- tick_do_update_jiffies64(now);
-
- /*
- * When we are idle and the tick is stopped, we have to touch
- * the watchdog as we might not schedule for a really long
- * time. This happens on complete idle SMP systems while
- * waiting on the login prompt. We also increment the "start
- * of idle" jiffy stamp so the idle accounting adjustment we
- * do when we go busy again does not account too much ticks.
- */
- if (ts->tick_stopped) {
- touch_softlockup_watchdog();
- ts->idle_jiffies++;
- }
-
- update_process_times(user_mode(regs));
- profile_tick(CPU_PROFILING);
+ tick_sched_do_timer(now);
+ tick_sched_handle(ts, regs);

while (tick_nohz_reprogram(ts, now)) {
now = ktime_get();
@@ -794,7 +809,7 @@ void tick_check_idle(int cpu)
#ifdef CONFIG_HIGH_RES_TIMERS
/*
* We rearm the timer until we get disabled by the idle code.
- * Called with interrupts disabled and timer->base->cpu_base->lock held.
+ * Called with interrupts disabled.
*/
static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer)
{
@@ -802,45 +817,15 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer)
container_of(timer, struct tick_sched, sched_timer);
struct pt_regs *regs = get_irq_regs();
ktime_t now = ktime_get();
- int cpu = smp_processor_id();

-#ifdef CONFIG_NO_HZ
- /*
- * Check if the do_timer duty was dropped. We don't care about
- * concurrency: This happens only when the cpu in charge went
- * into a long sleep. If two cpus happen to assign themself to
- * this duty, then the jiffies update is still serialized by
- * xtime_lock.
- */
- if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
- tick_do_timer_cpu = cpu;
-#endif
-
- /* Check, if the jiffies need an update */
- if (tick_do_timer_cpu == cpu)
- tick_do_update_jiffies64(now);
+ tick_sched_do_timer(now);

/*
* Do not call, when we are not in irq context and have
* no valid regs pointer
*/
- if (regs) {
- /*
- * When we are idle and the tick is stopped, we have to touch
- * the watchdog as we might not schedule for a really long
- * time. This happens on complete idle SMP systems while
- * waiting on the login prompt. We also increment the "start of
- * idle" jiffy stamp so the idle accounting adjustment we do
- * when we go busy again does not account too much ticks.
- */
- if (ts->tick_stopped) {
- touch_softlockup_watchdog();
- if (is_idle_task(current))
- ts->idle_jiffies++;
- }
- update_process_times(user_mode(regs));
- profile_tick(CPU_PROFILING);
- }
+ if (regs)
+ tick_sched_handle(ts, regs);

hrtimer_forward(timer, now, tick_period);

@@ -874,7 +859,7 @@ void tick_setup_sched_timer(void)
/* Get the next period (per cpu) */
hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update());

- /* Offset the tick to avert xtime_lock contention. */
+ /* Offset the tick to avert jiffies_lock contention. */
if (sched_skew_tick) {
u64 offset = ktime_to_ns(tick_period) >> 1;
do_div(offset, num_possible_cpus());
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index e424970..4c7de02 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -25,12 +25,6 @@

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);
-
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;

@@ -1299,9 +1293,7 @@ struct timespec get_monotonic_coarse(void)
}

/*
- * The 64-bit jiffies value is not atomic - you MUST NOT read it
- * without sampling the sequence number in xtime_lock.
- * jiffies is defined in the linker script...
+ * Must hold jiffies_lock
*/
void do_timer(unsigned long ticks)
{
@@ -1389,7 +1381,7 @@ EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset);
*/
void xtime_update(unsigned long ticks)
{
- write_seqlock(&xtime_lock);
+ write_seqlock(&jiffies_lock);
do_timer(ticks);
- write_sequnlock(&xtime_lock);
+ write_sequnlock(&jiffies_lock);
}
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