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Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull the leap second fixes from Thomas Gleixner:
 "It's a rather large series, but well discussed, refined and reviewed.
  It got a massive testing by John, Prarit and tip.

  In theory we could split it into two parts.  The first two patches

    f55a6faa3843: hrtimer: Provide clock_was_set_delayed()
    4873fa070ae8: timekeeping: Fix leapsecond triggered load spike issue

  are merely preventing the stuff loops forever issues, which people
  have observed.

  But there is no point in delaying the other 4 commits which achieve
  full correctness into 3.6 as they are tagged for stable anyway.  And I
  rather prefer to have the full fixes merged in bulk than a "prevent
  the observable wreckage and deal with the hidden fallout later"
  approach."

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  hrtimer: Update hrtimer base offsets each hrtimer_interrupt
  timekeeping: Provide hrtimer update function
  hrtimers: Move lock held region in hrtimer_interrupt()
  timekeeping: Maintain ktime_t based offsets for hrtimers
  timekeeping: Fix leapsecond triggered load spike issue
  hrtimer: Provide clock_was_set_delayed()
This commit is contained in:
Linus Torvalds 2012-07-13 15:31:21 -07:00
parent 5651721ede 5baefd6d84
commit d55e5bd020
3 changed files with 107 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
include/linux/hrtimer.h
View File

@ -165,6 +165,7 @@ enum hrtimer_base_type {
* @lock: lock protecting the base and associated clock bases
* and timers
* @active_bases: Bitfield to mark bases with active timers
* @clock_was_set: Indicates that clock was set from irq context.
* @expires_next: absolute time of the next event which was scheduled
* via clock_set_next_event()
* @hres_active: State of high resolution mode
@ -177,7 +178,8 @@ enum hrtimer_base_type {
*/
struct hrtimer_cpu_base {
raw_spinlock_t lock;
unsigned long active_bases;
unsigned int active_bases;
unsigned int clock_was_set;
#ifdef CONFIG_HIGH_RES_TIMERS
ktime_t expires_next;
int hres_active;
@ -286,6 +288,8 @@ extern void hrtimer_peek_ahead_timers(void);
# define MONOTONIC_RES_NSEC HIGH_RES_NSEC
# define KTIME_MONOTONIC_RES KTIME_HIGH_RES
extern void clock_was_set_delayed(void);
#else
# define MONOTONIC_RES_NSEC LOW_RES_NSEC
@ -306,6 +310,9 @@ static inline int hrtimer_is_hres_active(struct hrtimer *timer)
{
return 0;
}
static inline void clock_was_set_delayed(void) { }
#endif
extern void clock_was_set(void);
@ -320,6 +327,7 @@ extern ktime_t ktime_get(void);
extern ktime_t ktime_get_real(void);
extern ktime_t ktime_get_boottime(void);
extern ktime_t ktime_get_monotonic_offset(void);
extern ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot);
DECLARE_PER_CPU(struct tick_device, tick_cpu_device);

53
kernel/hrtimer.c
View File

@ -657,6 +657,14 @@ static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
return 0;
}
static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
{
ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
return ktime_get_update_offsets(offs_real, offs_boot);
}
/*
* Retrigger next event is called after clock was set
*
@ -665,22 +673,12 @@ static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
static void retrigger_next_event(void *arg)
{
struct hrtimer_cpu_base *base = &__get_cpu_var(hrtimer_bases);
struct timespec realtime_offset, xtim, wtm, sleep;
if (!hrtimer_hres_active())
return;
/* Optimized out for !HIGH_RES */
get_xtime_and_monotonic_and_sleep_offset(&xtim, &wtm, &sleep);
set_normalized_timespec(&realtime_offset, -wtm.tv_sec, -wtm.tv_nsec);
/* Adjust CLOCK_REALTIME offset */
raw_spin_lock(&base->lock);
base->clock_base[HRTIMER_BASE_REALTIME].offset =
timespec_to_ktime(realtime_offset);
base->clock_base[HRTIMER_BASE_BOOTTIME].offset =
timespec_to_ktime(sleep);
hrtimer_update_base(base);
hrtimer_force_reprogram(base, 0);
raw_spin_unlock(&base->lock);
}
@ -710,13 +708,25 @@ static int hrtimer_switch_to_hres(void)
base->clock_base[i].resolution = KTIME_HIGH_RES;
tick_setup_sched_timer();
/* "Retrigger" the interrupt to get things going */
retrigger_next_event(NULL);
local_irq_restore(flags);
return 1;
}
/*
* Called from timekeeping code to reprogramm the hrtimer interrupt
* device. If called from the timer interrupt context we defer it to
* softirq context.
*/
void clock_was_set_delayed(void)
{
struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
cpu_base->clock_was_set = 1;
__raise_softirq_irqoff(HRTIMER_SOFTIRQ);
}
#else
static inline int hrtimer_hres_active(void) { return 0; }
@ -1250,11 +1260,10 @@ void hrtimer_interrupt(struct clock_event_device *dev)
cpu_base->nr_events++;
dev->next_event.tv64 = KTIME_MAX;
entry_time = now = ktime_get();
raw_spin_lock(&cpu_base->lock);
entry_time = now = hrtimer_update_base(cpu_base);
retry:
expires_next.tv64 = KTIME_MAX;
raw_spin_lock(&cpu_base->lock);
/*
* We set expires_next to KTIME_MAX here with cpu_base->lock
* held to prevent that a timer is enqueued in our queue via
@ -1330,8 +1339,12 @@ void hrtimer_interrupt(struct clock_event_device *dev)
* We need to prevent that we loop forever in the hrtimer
* interrupt routine. We give it 3 attempts to avoid
* overreacting on some spurious event.
*
* Acquire base lock for updating the offsets and retrieving
* the current time.
*/
now = ktime_get();
raw_spin_lock(&cpu_base->lock);
now = hrtimer_update_base(cpu_base);
cpu_base->nr_retries++;
if (++retries < 3)
goto retry;
@ -1343,6 +1356,7 @@ void hrtimer_interrupt(struct clock_event_device *dev)
*/
cpu_base->nr_hangs++;
cpu_base->hang_detected = 1;
raw_spin_unlock(&cpu_base->lock);
delta = ktime_sub(now, entry_time);
if (delta.tv64 > cpu_base->max_hang_time.tv64)
cpu_base->max_hang_time = delta;
@ -1395,6 +1409,13 @@ void hrtimer_peek_ahead_timers(void)
static void run_hrtimer_softirq(struct softirq_action *h)
{
struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
if (cpu_base->clock_was_set) {
cpu_base->clock_was_set = 0;
clock_was_set();
}
hrtimer_peek_ahead_timers();
}

63
kernel/time/timekeeping.c
View File

@ -70,6 +70,12 @@ struct timekeeper {
/* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */
struct timespec raw_time;
/* Offset clock monotonic -> clock realtime */
ktime_t offs_real;
/* Offset clock monotonic -> clock boottime */
ktime_t offs_boot;
/* Seqlock for all timekeeper values */
seqlock_t lock;
};
@ -172,6 +178,14 @@ static inline s64 timekeeping_get_ns_raw(void)
return clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
}
static void update_rt_offset(void)
{
struct timespec tmp, *wtm = &timekeeper.wall_to_monotonic;
set_normalized_timespec(&tmp, -wtm->tv_sec, -wtm->tv_nsec);
timekeeper.offs_real = timespec_to_ktime(tmp);
}
/* must hold write on timekeeper.lock */
static void timekeeping_update(bool clearntp)
{
@ -179,6 +193,7 @@ static void timekeeping_update(bool clearntp)
timekeeper.ntp_error = 0;
ntp_clear();
}
update_rt_offset();
update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,
timekeeper.clock, timekeeper.mult);
}
@ -604,6 +619,7 @@ void __init timekeeping_init(void)
}
set_normalized_timespec(&timekeeper.wall_to_monotonic,
-boot.tv_sec, -boot.tv_nsec);
update_rt_offset();
timekeeper.total_sleep_time.tv_sec = 0;
timekeeper.total_sleep_time.tv_nsec = 0;
write_sequnlock_irqrestore(&timekeeper.lock, flags);
@ -612,6 +628,12 @@ void __init timekeeping_init(void)
/* time in seconds when suspend began */
static struct timespec timekeeping_suspend_time;
static void update_sleep_time(struct timespec t)
{
timekeeper.total_sleep_time = t;
timekeeper.offs_boot = timespec_to_ktime(t);
}
/**
* __timekeeping_inject_sleeptime - Internal function to add sleep interval
* @delta: pointer to a timespec delta value
@ -630,8 +652,7 @@ static void __timekeeping_inject_sleeptime(struct timespec *delta)
timekeeper.xtime = timespec_add(timekeeper.xtime, *delta);
timekeeper.wall_to_monotonic =
timespec_sub(timekeeper.wall_to_monotonic, *delta);
timekeeper.total_sleep_time = timespec_add(
timekeeper.total_sleep_time, *delta);
update_sleep_time(timespec_add(timekeeper.total_sleep_time, *delta));
}
@ -963,6 +984,8 @@ static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
leap = second_overflow(timekeeper.xtime.tv_sec);
timekeeper.xtime.tv_sec += leap;
timekeeper.wall_to_monotonic.tv_sec -= leap;
if (leap)
clock_was_set_delayed();
}
/* Accumulate raw time */
@ -1079,6 +1102,8 @@ static void update_wall_time(void)
leap = second_overflow(timekeeper.xtime.tv_sec);
timekeeper.xtime.tv_sec += leap;
timekeeper.wall_to_monotonic.tv_sec -= leap;
if (leap)
clock_was_set_delayed();
}
timekeeping_update(false);
@ -1246,6 +1271,40 @@ void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
} while (read_seqretry(&timekeeper.lock, seq));
}
#ifdef CONFIG_HIGH_RES_TIMERS
/**
* ktime_get_update_offsets - hrtimer helper
* @offs_real: pointer to storage for monotonic -> realtime offset
* @offs_boot: pointer to storage for monotonic -> boottime offset
*
* Returns current monotonic time and updates the offsets
* Called from hrtimer_interupt() or retrigger_next_event()
*/
ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot)
{
ktime_t now;
unsigned int seq;
u64 secs, nsecs;
do {
seq = read_seqbegin(&timekeeper.lock);
secs = timekeeper.xtime.tv_sec;
nsecs = timekeeper.xtime.tv_nsec;
nsecs += timekeeping_get_ns();
/* If arch requires, add in gettimeoffset() */
nsecs += arch_gettimeoffset();
*offs_real = timekeeper.offs_real;
*offs_boot = timekeeper.offs_boot;
} while (read_seqretry(&timekeeper.lock, seq));
now = ktime_add_ns(ktime_set(secs, 0), nsecs);
now = ktime_sub(now, *offs_real);
return now;
}
#endif
/**
* ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
*/