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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-09-08 01:01:14 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-09-08 01:01:14 -0300
commite5fd91f1ef340da553f7a79da9540c3db711c937 (patch)
treeb11842027dc6641da63f4bcc524f8678263304a3 /kernel/time/timekeeping.c
parent2a9b0348e685a63d97486f6749622b61e9e3292f (diff)
Linux-libre 4.2-gnu
Diffstat (limited to 'kernel/time/timekeeping.c')
-rw-r--r--kernel/time/timekeeping.c182
1 files changed, 79 insertions, 103 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 946acb721..bca3667a2 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -118,18 +118,6 @@ static inline void tk_update_sleep_time(struct timekeeper *tk, ktime_t delta)
#ifdef CONFIG_DEBUG_TIMEKEEPING
#define WARNING_FREQ (HZ*300) /* 5 minute rate-limiting */
-/*
- * These simple flag variables are managed
- * without locks, which is racy, but ok since
- * we don't really care about being super
- * precise about how many events were seen,
- * just that a problem was observed.
- */
-static int timekeeping_underflow_seen;
-static int timekeeping_overflow_seen;
-
-/* last_warning is only modified under the timekeeping lock */
-static long timekeeping_last_warning;
static void timekeeping_check_update(struct timekeeper *tk, cycle_t offset)
{
@@ -149,29 +137,30 @@ static void timekeeping_check_update(struct timekeeper *tk, cycle_t offset)
}
}
- if (timekeeping_underflow_seen) {
- if (jiffies - timekeeping_last_warning > WARNING_FREQ) {
+ if (tk->underflow_seen) {
+ if (jiffies - tk->last_warning > WARNING_FREQ) {
printk_deferred("WARNING: Underflow in clocksource '%s' observed, time update ignored.\n", name);
printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
printk_deferred(" Your kernel is probably still fine.\n");
- timekeeping_last_warning = jiffies;
+ tk->last_warning = jiffies;
}
- timekeeping_underflow_seen = 0;
+ tk->underflow_seen = 0;
}
- if (timekeeping_overflow_seen) {
- if (jiffies - timekeeping_last_warning > WARNING_FREQ) {
+ if (tk->overflow_seen) {
+ if (jiffies - tk->last_warning > WARNING_FREQ) {
printk_deferred("WARNING: Overflow in clocksource '%s' observed, time update capped.\n", name);
printk_deferred(" Please report this, consider using a different clocksource, if possible.\n");
printk_deferred(" Your kernel is probably still fine.\n");
- timekeeping_last_warning = jiffies;
+ tk->last_warning = jiffies;
}
- timekeeping_overflow_seen = 0;
+ tk->overflow_seen = 0;
}
}
static inline cycle_t timekeeping_get_delta(struct tk_read_base *tkr)
{
+ struct timekeeper *tk = &tk_core.timekeeper;
cycle_t now, last, mask, max, delta;
unsigned int seq;
@@ -197,13 +186,13 @@ static inline cycle_t timekeeping_get_delta(struct tk_read_base *tkr)
* mask-relative negative values.
*/
if (unlikely((~delta & mask) < (mask >> 3))) {
- timekeeping_underflow_seen = 1;
+ tk->underflow_seen = 1;
delta = 0;
}
/* Cap delta value to the max_cycles values to avoid mult overflows */
if (unlikely(delta > max)) {
- timekeeping_overflow_seen = 1;
+ tk->overflow_seen = 1;
delta = tkr->clock->max_cycles;
}
@@ -330,32 +319,7 @@ static inline s64 timekeeping_get_ns(struct tk_read_base *tkr)
* We want to use this from any context including NMI and tracing /
* instrumenting the timekeeping code itself.
*
- * So we handle this differently than the other timekeeping accessor
- * functions which retry when the sequence count has changed. The
- * update side does:
- *
- * smp_wmb(); <- Ensure that the last base[1] update is visible
- * tkf->seq++;
- * smp_wmb(); <- Ensure that the seqcount update is visible
- * update(tkf->base[0], tkr);
- * smp_wmb(); <- Ensure that the base[0] update is visible
- * tkf->seq++;
- * smp_wmb(); <- Ensure that the seqcount update is visible
- * update(tkf->base[1], tkr);
- *
- * The reader side does:
- *
- * do {
- * seq = tkf->seq;
- * smp_rmb();
- * idx = seq & 0x01;
- * now = now(tkf->base[idx]);
- * smp_rmb();
- * } while (seq != tkf->seq)
- *
- * As long as we update base[0] readers are forced off to
- * base[1]. Once base[0] is updated readers are redirected to base[0]
- * and the base[1] update takes place.
+ * Employ the latch technique; see @raw_write_seqcount_latch.
*
* So if a NMI hits the update of base[0] then it will use base[1]
* which is still consistent. In the worst case this can result is a
@@ -418,7 +382,7 @@ static __always_inline u64 __ktime_get_fast_ns(struct tk_fast *tkf)
u64 now;
do {
- seq = raw_read_seqcount(&tkf->seq);
+ seq = raw_read_seqcount_latch(&tkf->seq);
tkr = tkf->base + (seq & 0x01);
now = ktime_to_ns(tkr->base) + timekeeping_get_ns(tkr);
} while (read_seqcount_retry(&tkf->seq, seq));
@@ -551,6 +515,17 @@ int pvclock_gtod_unregister_notifier(struct notifier_block *nb)
EXPORT_SYMBOL_GPL(pvclock_gtod_unregister_notifier);
/*
+ * tk_update_leap_state - helper to update the next_leap_ktime
+ */
+static inline void tk_update_leap_state(struct timekeeper *tk)
+{
+ tk->next_leap_ktime = ntp_get_next_leap();
+ if (tk->next_leap_ktime.tv64 != KTIME_MAX)
+ /* Convert to monotonic time */
+ tk->next_leap_ktime = ktime_sub(tk->next_leap_ktime, tk->offs_real);
+}
+
+/*
* Update the ktime_t based scalar nsec members of the timekeeper
*/
static inline void tk_update_ktime_data(struct timekeeper *tk)
@@ -591,17 +566,25 @@ static void timekeeping_update(struct timekeeper *tk, unsigned int action)
ntp_clear();
}
+ tk_update_leap_state(tk);
tk_update_ktime_data(tk);
update_vsyscall(tk);
update_pvclock_gtod(tk, action & TK_CLOCK_WAS_SET);
+ update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
+ update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);
+
+ if (action & TK_CLOCK_WAS_SET)
+ tk->clock_was_set_seq++;
+ /*
+ * The mirroring of the data to the shadow-timekeeper needs
+ * to happen last here to ensure we don't over-write the
+ * timekeeper structure on the next update with stale data
+ */
if (action & TK_MIRROR)
memcpy(&shadow_timekeeper, &tk_core.timekeeper,
sizeof(tk_core.timekeeper));
-
- update_fast_timekeeper(&tk->tkr_mono, &tk_fast_mono);
- update_fast_timekeeper(&tk->tkr_raw, &tk_fast_raw);
}
/**
@@ -699,6 +682,23 @@ ktime_t ktime_get(void)
}
EXPORT_SYMBOL_GPL(ktime_get);
+u32 ktime_get_resolution_ns(void)
+{
+ struct timekeeper *tk = &tk_core.timekeeper;
+ unsigned int seq;
+ u32 nsecs;
+
+ WARN_ON(timekeeping_suspended);
+
+ do {
+ seq = read_seqcount_begin(&tk_core.seq);
+ nsecs = tk->tkr_mono.mult >> tk->tkr_mono.shift;
+ } while (read_seqcount_retry(&tk_core.seq, seq));
+
+ return nsecs;
+}
+EXPORT_SYMBOL_GPL(ktime_get_resolution_ns);
+
static ktime_t *offsets[TK_OFFS_MAX] = {
[TK_OFFS_REAL] = &tk_core.timekeeper.offs_real,
[TK_OFFS_BOOT] = &tk_core.timekeeper.offs_boot,
@@ -1179,28 +1179,20 @@ void __weak read_persistent_clock64(struct timespec64 *ts64)
}
/**
- * read_boot_clock - Return time of the system start.
+ * read_boot_clock64 - Return time of the system start.
*
* Weak dummy function for arches that do not yet support it.
* Function to read the exact time the system has been started.
- * Returns a timespec with tv_sec=0 and tv_nsec=0 if unsupported.
+ * Returns a timespec64 with tv_sec=0 and tv_nsec=0 if unsupported.
*
* XXX - Do be sure to remove it once all arches implement it.
*/
-void __weak read_boot_clock(struct timespec *ts)
+void __weak read_boot_clock64(struct timespec64 *ts)
{
ts->tv_sec = 0;
ts->tv_nsec = 0;
}
-void __weak read_boot_clock64(struct timespec64 *ts64)
-{
- struct timespec ts;
-
- read_boot_clock(&ts);
- *ts64 = timespec_to_timespec64(ts);
-}
-
/* Flag for if timekeeping_resume() has injected sleeptime */
static bool sleeptime_injected;
@@ -1836,8 +1828,9 @@ void update_wall_time(void)
* memcpy under the tk_core.seq against one before we start
* updating.
*/
+ timekeeping_update(tk, clock_set);
memcpy(real_tk, tk, sizeof(*tk));
- timekeeping_update(real_tk, clock_set);
+ /* The memcpy must come last. Do not put anything here! */
write_seqcount_end(&tk_core.seq);
out:
raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
@@ -1926,47 +1919,20 @@ void do_timer(unsigned long ticks)
}
/**
- * ktime_get_update_offsets_tick - hrtimer helper
- * @offs_real: pointer to storage for monotonic -> realtime offset
- * @offs_boot: pointer to storage for monotonic -> boottime offset
- * @offs_tai: pointer to storage for monotonic -> clock tai offset
- *
- * Returns monotonic time at last tick and various offsets
- */
-ktime_t ktime_get_update_offsets_tick(ktime_t *offs_real, ktime_t *offs_boot,
- ktime_t *offs_tai)
-{
- struct timekeeper *tk = &tk_core.timekeeper;
- unsigned int seq;
- ktime_t base;
- u64 nsecs;
-
- do {
- seq = read_seqcount_begin(&tk_core.seq);
-
- base = tk->tkr_mono.base;
- nsecs = tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift;
-
- *offs_real = tk->offs_real;
- *offs_boot = tk->offs_boot;
- *offs_tai = tk->offs_tai;
- } while (read_seqcount_retry(&tk_core.seq, seq));
-
- return ktime_add_ns(base, nsecs);
-}
-
-#ifdef CONFIG_HIGH_RES_TIMERS
-/**
* ktime_get_update_offsets_now - hrtimer helper
+ * @cwsseq: pointer to check and store the clock was set sequence number
* @offs_real: pointer to storage for monotonic -> realtime offset
* @offs_boot: pointer to storage for monotonic -> boottime offset
* @offs_tai: pointer to storage for monotonic -> clock tai offset
*
- * Returns current monotonic time and updates the offsets
+ * Returns current monotonic time and updates the offsets if the
+ * sequence number in @cwsseq and timekeeper.clock_was_set_seq are
+ * different.
+ *
* Called from hrtimer_interrupt() or retrigger_next_event()
*/
-ktime_t ktime_get_update_offsets_now(ktime_t *offs_real, ktime_t *offs_boot,
- ktime_t *offs_tai)
+ktime_t ktime_get_update_offsets_now(unsigned int *cwsseq, ktime_t *offs_real,
+ ktime_t *offs_boot, ktime_t *offs_tai)
{
struct timekeeper *tk = &tk_core.timekeeper;
unsigned int seq;
@@ -1978,15 +1944,23 @@ ktime_t ktime_get_update_offsets_now(ktime_t *offs_real, ktime_t *offs_boot,
base = tk->tkr_mono.base;
nsecs = timekeeping_get_ns(&tk->tkr_mono);
+ base = ktime_add_ns(base, nsecs);
+
+ if (*cwsseq != tk->clock_was_set_seq) {
+ *cwsseq = tk->clock_was_set_seq;
+ *offs_real = tk->offs_real;
+ *offs_boot = tk->offs_boot;
+ *offs_tai = tk->offs_tai;
+ }
+
+ /* Handle leapsecond insertion adjustments */
+ if (unlikely(base.tv64 >= tk->next_leap_ktime.tv64))
+ *offs_real = ktime_sub(tk->offs_real, ktime_set(1, 0));
- *offs_real = tk->offs_real;
- *offs_boot = tk->offs_boot;
- *offs_tai = tk->offs_tai;
} while (read_seqcount_retry(&tk_core.seq, seq));
- return ktime_add_ns(base, nsecs);
+ return base;
}
-#endif
/**
* do_adjtimex() - Accessor function to NTP __do_adjtimex function
@@ -2027,6 +2001,8 @@ int do_adjtimex(struct timex *txc)
__timekeeping_set_tai_offset(tk, tai);
timekeeping_update(tk, TK_MIRROR | TK_CLOCK_WAS_SET);
}
+ tk_update_leap_state(tk);
+
write_seqcount_end(&tk_core.seq);
raw_spin_unlock_irqrestore(&timekeeper_lock, flags);