[RFC][patch 08/12] introduce struct timekeeper

Martin Schwidefsky
2009-07-29T13:42:37Z

[-- Attachment #1: timekeeper-struct.diff --]
[-- Type: text/plain, Size: 22103 bytes --]

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

Add struct timekeeper to keep the internal values timekeeping.c needs
in regard to the currently selected clock source. This moves the
timekeeping intervals, xtime_nsec and the ntp error value from
struct clocksource to struct timekeeper. The raw_time is removed from
the clocksource as well. It gets treated like xtime as a global variable.
Eventually xtime raw_time should be moved to struct timekeeper.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Daniel Walker <dwalker@fifo99.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
arch/s390/kernel/time.c | 1
include/linux/clocksource.h | 54 ----------
kernel/time/clocksource.c | 6 -
kernel/time/timekeeping.c | 223 ++++++++++++++++++++++++++++----------------
4 files changed, 152 insertions(+), 132 deletions(-)

Index: linux-2.6/arch/s390/kernel/time.c
===================================================================
--- linux-2.6.orig/arch/s390/kernel/time.c
+++ linux-2.6/arch/s390/kernel/time.c
@@ -280,7 +280,6 @@ void __init time_init(void)
now = get_clock();
tod_to_timeval(now - TOD_UNIX_EPOCH, &xtime);
clocksource_tod.cycle_last = now;
- clocksource_tod.raw_time = xtime;
tod_to_timeval(sched_clock_base_cc - TOD_UNIX_EPOCH, &ts);
set_normalized_timespec(&wall_to_monotonic, -ts.tv_sec, -ts.tv_nsec);
write_sequnlock_irqrestore(&xtime_lock, flags);
Index: linux-2.6/include/linux/clocksource.h
===================================================================
--- linux-2.6.orig/include/linux/clocksource.h
+++ linux-2.6/include/linux/clocksource.h
@@ -155,8 +155,6 @@ extern u64 timecounter_cyc2time(struct t
* @flags: flags describing special properties
* @vread: vsyscall based read
* @resume: resume function for the clocksource, if necessary
- * @cycle_interval: Used internally by timekeeping core, please ignore.
- * @xtime_interval: Used internally by timekeeping core, please ignore.
*/
struct clocksource {
/*
@@ -182,19 +180,12 @@ struct clocksource {
#define CLKSRC_FSYS_MMIO_SET(mmio, addr) do { } while (0)
#endif

- /* timekeeping specific data, ignore */
- cycle_t cycle_interval;
- u64 xtime_interval;
- u32 raw_interval;
/*
* Second part is written at each timer interrupt
* Keep it in a different cache line to dirty no
* more than one cache line.
*/
cycle_t cycle_last ____cacheline_aligned_in_smp;
- u64 xtime_nsec;
- s64 error;
- struct timespec raw_time;

#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
/* Watchdog related data, used by the framework */
@@ -203,8 +194,6 @@ struct clocksource {
#endif
};

-extern struct clocksource *clock; /* current clocksource */
-
/*
* Clock source flags bits::
*/
@@ -270,50 +259,15 @@ static inline u32 clocksource_hz2mult(u3
}

/**
- * cyc2ns - converts clocksource cycles to nanoseconds
- * @cs: Pointer to clocksource
- * @cycles: Cycles
+ * clocksource_cyc2ns - converts clocksource cycles to nanoseconds
*
- * Uses the clocksource and ntp ajdustment to convert cycle_ts to nanoseconds.
+ * Converts cycles to nanoseconds, using the given mult and shift.
*
* XXX - This could use some mult_lxl_ll() asm optimization
*/
-static inline s64 cyc2ns(struct clocksource *cs, cycle_t cycles)
-{
- u64 ret = (u64)cycles;
- ret = (ret * cs->mult) >> cs->shift;
- return ret;
-}
-
-/**
- * clocksource_calculate_interval - Calculates a clocksource interval struct
- *
- * @c: Pointer to clocksource.
- * @length_nsec: Desired interval length in nanoseconds.
- *
- * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
- * pair and interval request.
- *
- * Unless you're the timekeeping code, you should not be using this!
- */
-static inline void clocksource_calculate_interval(struct clocksource *c,
- unsigned long length_nsec)
+static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift)
{
- u64 tmp;
-
- /* Do the ns -> cycle conversion first, using original mult */
- tmp = length_nsec;
- tmp <<= c->shift;
- tmp += c->mult_orig/2;
- do_div(tmp, c->mult_orig);
-
- c->cycle_interval = (cycle_t)tmp;
- if (c->cycle_interval == 0)
- c->cycle_interval = 1;
-
- /* Go back from cycles -> shifted ns, this time use ntp adjused mult */
- c->xtime_interval = (u64)c->cycle_interval * c->mult;
- c->raw_interval = ((u64)c->cycle_interval * c->mult_orig) >> c->shift;
+ return ((u64) cycles * mult) >> shift;
}

Index: linux-2.6/kernel/time/clocksource.c
===================================================================
--- linux-2.6.orig/kernel/time/clocksource.c
+++ linux-2.6/kernel/time/clocksource.c
@@ -177,7 +177,8 @@ static void clocksource_watchdog(unsigne
goto out;

wdnow = watchdog->read(watchdog);
- wd_nsec = cyc2ns(watchdog, (wdnow - watchdog_last) & watchdog->mask);
+ wd_nsec = clocksource_cyc2ns((wdnow - watchdog_last) & watchdog->mask,
+ watchdog->mult, watchdog->shift);
watchdog_last = wdnow;

list_for_each_entry(cs, &watchdog_list, wd_list) {
@@ -196,7 +197,8 @@ static void clocksource_watchdog(unsigne
}

/* Check the deviation from the watchdog clocksource. */
- cs_nsec = cyc2ns(cs, (csnow - cs->wd_last) & cs->mask);
+ cs_nsec = clocksource_cyc2ns((csnow - cs->wd_last) &
+ cs->mask, cs->mult, cs->shift);
cs->wd_last = csnow;
if (abs(cs_nsec - wd_nsec) > WATCHDOG_THRESHOLD) {
clocksource_unstable(cs, cs_nsec - wd_nsec);
Index: linux-2.6/kernel/time/timekeeping.c
===================================================================
--- linux-2.6.orig/kernel/time/timekeeping.c
+++ linux-2.6/kernel/time/timekeeping.c
@@ -19,6 +19,56 @@
#include <linux/time.h>
#include <linux/tick.h>

+/* Structure holding internal timekeeping values. */
+struct timekeeper {
+ struct clocksource *clock;
+ cycle_t cycle_interval;
+ u64 xtime_interval;
+ u32 raw_interval;
+ u64 xtime_nsec;
+ s64 ntp_error;
+};
+
+struct timekeeper timekeeper;
+
+/**
+ * timekeeper_setup_internals - Set up internals to use clocksource clock.
+ *
+ * @clock: Pointer to clocksource.
+ *
+ * Calculates a fixed cycle/nsec interval for a given clocksource/adjustment
+ * pair and interval request.
+ *
+ * Unless you're the timekeeping code, you should not be using this!
+ */
+static void timekeeper_setup_internals(struct clocksource *clock)
+{
+ cycle_t interval;
+ u64 tmp;
+
+ timekeeper.clock = clock;
+ clock->cycle_last = clock->read(clock);
+
+ /* Do the ns -> cycle conversion first, using original mult */
+ tmp = NTP_INTERVAL_LENGTH;
+ tmp <<= clock->shift;
+ tmp += clock->mult_orig/2;
+ do_div(tmp, clock->mult_orig);
+ if (tmp == 0)
+ tmp = 1;
+
+ interval = (cycle_t) tmp;
+ timekeeper.cycle_interval = interval;
+
+ /* Go back from cycles -> shifted ns */
+ timekeeper.xtime_interval = (u64) interval * clock->mult;
+ timekeeper.raw_interval =
+ ((u64) interval * clock->mult_orig) >> clock->shift;
+
+ timekeeper.xtime_nsec = 0;
+
+ timekeeper.ntp_error = 0;
+}

/*
* This read-write spinlock protects us from races in SMP while
@@ -46,6 +96,11 @@ struct timespec xtime __attribute__ ((al
struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
static unsigned long total_sleep_time; /* seconds */

+/*
+ * The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock.
+ */
+struct timespec raw_time;
+
/* flag for if timekeeping is suspended */
int __read_mostly timekeeping_suspended;

@@ -56,42 +111,42 @@ void update_xtime_cache(u64 nsec)
timespec_add_ns(&xtime_cache, nsec);
}

-struct clocksource *clock;
-
/* must hold xtime_lock */
void timekeeping_leap_insert(int leapsecond)
{
xtime.tv_sec += leapsecond;
wall_to_monotonic.tv_sec -= leapsecond;
- update_vsyscall(&xtime, clock);
+ update_vsyscall(&xtime, timekeeper.clock);
}

#ifdef CONFIG_GENERIC_TIME
/**
- * clocksource_forward_now - update clock to the current time
+ * timekeeping_forward_now - update clock to the current time
*
* Forward the current clock to update its state since the last call to
* update_wall_time(). This is useful before significant clock changes,
* as it avoids having to deal with this time offset explicitly.
*/
-static void clocksource_forward_now(void)
+static void timekeeping_forward_now(void)
{
cycle_t cycle_now, cycle_delta;
+ struct clocksource *clock;
s64 nsec;

+ clock = timekeeper.clock;
cycle_now = clock->read(clock);
cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;
clock->cycle_last = cycle_now;

- nsec = cyc2ns(clock, cycle_delta);
+ nsec = clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);

/* If arch requires, add in gettimeoffset() */
nsec += arch_gettimeoffset();

timespec_add_ns(&xtime, nsec);

- nsec = ((s64)cycle_delta * clock->mult_orig) >> clock->shift;
- clock->raw_time.tv_nsec += nsec;
+ nsec = clocksource_cyc2ns(cycle_delta, clock->mult_orig, clock->shift);
+ timespec_add_ns(&raw_time, nsec);
}

/**
@@ -103,6 +158,7 @@ static void clocksource_forward_now(void
void getnstimeofday(struct timespec *ts)
{
cycle_t cycle_now, cycle_delta;
+ struct clocksource *clock;
unsigned long seq;
s64 nsecs;

@@ -114,13 +170,15 @@ void getnstimeofday(struct timespec *ts)
*ts = xtime;

/* read clocksource: */
+ clock = timekeeper.clock;
cycle_now = clock->read(clock);

/* calculate the delta since the last update_wall_time: */
cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;

/* convert to nanoseconds: */
- nsecs = cyc2ns(clock, cycle_delta);
+ nsecs = clocksource_cyc2ns(cycle_delta, clock->mult,
+ clock->shift);

/* If arch requires, add in gettimeoffset() */
nsecs += arch_gettimeoffset();
@@ -135,6 +193,7 @@ EXPORT_SYMBOL(getnstimeofday);
ktime_t ktime_get(void)
{
cycle_t cycle_now, cycle_delta;
+ struct clocksource *clock;
unsigned int seq;
s64 secs, nsecs;

@@ -146,13 +205,15 @@ ktime_t ktime_get(void)
nsecs = xtime.tv_nsec + wall_to_monotonic.tv_nsec;

/* read clocksource: */
+ clock = timekeeper.clock;
cycle_now = clock->read(clock);

/* calculate the delta since the last update_wall_time: */
cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;

/* convert to nanoseconds: */
- nsecs += cyc2ns(clock, cycle_delta);
+ nsecs += clocksource_cyc2ns(cycle_delta, clock->mult,
+ clock->shift);

} while (read_seqretry(&xtime_lock, seq));
/*
@@ -174,6 +235,7 @@ EXPORT_SYMBOL_GPL(ktime_get);
void ktime_get_ts(struct timespec *ts)
{
cycle_t cycle_now, cycle_delta;
+ struct clocksource *clock;
struct timespec tomono;
unsigned int seq;
s64 nsecs;
@@ -186,13 +248,15 @@ void ktime_get_ts(struct timespec *ts)
tomono = wall_to_monotonic;

/* read clocksource: */
+ clock = timekeeper.clock;
cycle_now = clock->read(clock);

/* calculate the delta since the last update_wall_time: */
cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;

/* convert to nanoseconds: */
- nsecs = cyc2ns(clock, cycle_delta);
+ nsecs = clocksource_cyc2ns(cycle_delta, clock->mult,
+ clock->shift);

} while (read_seqretry(&xtime_lock, seq));

@@ -233,7 +297,7 @@ int do_settimeofday(struct timespec *tv)

write_seqlock_irqsave(&xtime_lock, flags);

- clocksource_forward_now();
+ timekeeping_forward_now();

ts_delta.tv_sec = tv->tv_sec - xtime.tv_sec;
ts_delta.tv_nsec = tv->tv_nsec - xtime.tv_nsec;
@@ -243,10 +307,10 @@ int do_settimeofday(struct timespec *tv)

update_xtime_cache(0);

- clock->error = 0;
+ timekeeper.ntp_error = 0;
ntp_clear();

- update_vsyscall(&xtime, clock);
+ update_vsyscall(&xtime, timekeeper.clock);

write_sequnlock_irqrestore(&xtime_lock, flags);

@@ -269,38 +333,25 @@ static void change_clocksource(void)

new = clocksource_get_next();

- if (!new || clock == new)
+ if (!new || timekeeper.clock == new)
return;

- clocksource_forward_now();
+ timekeeping_forward_now();

if (new->enable && ! new->enable(new))
return;
/* save mult_orig on enable */
new->mult_orig = new->mult;

- new->raw_time = clock->raw_time;
- old = clock;
- clock = new;
+ old = timekeeper.clock;
+ timekeeper_setup_internals(new);
if (old->disable)
old->disable(old);

- clock->cycle_last = clock->read(clock);
- clock->error = 0;
- clock->xtime_nsec = 0;
- clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
-
tick_clock_notify();
-
- /*
- * We're holding xtime lock and waking up klogd would deadlock
- * us on enqueue. So no printing!
- printk(KERN_INFO "Time: %s clocksource has been installed.\n",
- clock->name);
- */
}
#else /* GENERIC_TIME */
-static inline void clocksource_forward_now(void) { }
+static inline void timekeeping_forward_now(void) { }
static inline void change_clocksource(void) { }

/**
@@ -370,20 +421,23 @@ void getrawmonotonic(struct timespec *ts
unsigned long seq;
s64 nsecs;
cycle_t cycle_now, cycle_delta;
+ struct clocksource *clock;

do {
seq = read_seqbegin(&xtime_lock);

/* read clocksource: */
+ clock = timekeeper.clock;
cycle_now = clock->read(clock);

/* calculate the delta since the last update_wall_time: */
cycle_delta = (cycle_now - clock->cycle_last) & clock->mask;

/* convert to nanoseconds: */
- nsecs = ((s64)cycle_delta * clock->mult_orig) >> clock->shift;
+ nsecs = clocksource_cyc2ns(cycle_delta, clock->mult_orig,
+ clock->shift);

- *ts = clock->raw_time;
+ *ts = raw_time;

} while (read_seqretry(&xtime_lock, seq));

@@ -403,7 +457,7 @@ int timekeeping_valid_for_hres(void)
do {
seq = read_seqbegin(&xtime_lock);

- ret = clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
+ ret = timekeeper.clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;

} while (read_seqretry(&xtime_lock, seq));

@@ -429,6 +483,7 @@ unsigned long __attribute__((weak)) read
*/
void __init timekeeping_init(void)
{
+ struct clocksource *clock;
unsigned long flags;
unsigned long sec = read_persistent_clock();

@@ -441,11 +496,13 @@ void __init timekeeping_init(void)
clock->enable(clock);
/* save mult_orig on enable */
clock->mult_orig = clock->mult;
- clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
- clock->cycle_last = clock->read(clock);
+
+ timekeeper_setup_internals(clock);

xtime.tv_sec = sec;
xtime.tv_nsec = 0;
+ raw_time.tv_sec = 0;
+ raw_time.tv_nsec = 0;
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
update_xtime_cache(0);
@@ -482,8 +539,8 @@ static int timekeeping_resume(struct sys
}
update_xtime_cache(0);
/* re-base the last cycle value */
- clock->cycle_last = clock->read(clock);
- clock->error = 0;
+ timekeeper.clock->cycle_last = timekeeper.clock->read(timekeeper.clock);
+ timekeeper.ntp_error = 0;
timekeeping_suspended = 0;
write_sequnlock_irqrestore(&xtime_lock, flags);

@@ -504,7 +561,7 @@ static int timekeeping_suspend(struct sy
timekeeping_suspend_time = read_persistent_clock();

write_seqlock_irqsave(&xtime_lock, flags);
- clocksource_forward_now();
+ timekeeping_forward_now();
timekeeping_suspended = 1;
write_sequnlock_irqrestore(&xtime_lock, flags);

@@ -539,7 +596,7 @@ device_initcall(timekeeping_init_device)
* If the error is already larger, we look ahead even further
* to compensate for late or lost adjustments.
*/
-static __always_inline int clocksource_bigadjust(s64 error, s64 *interval,
+static __always_inline int timekeeping_bigadjust(s64 error, s64 *interval,
s64 *offset)
{
s64 tick_error, i;
@@ -555,7 +612,7 @@ static __always_inline int clocksource_b
* here. This is tuned so that an error of about 1 msec is adjusted
* within about 1 sec (or 2^20 nsec in 2^SHIFT_HZ ticks).
*/
- error2 = clock->error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
+ error2 = timekeeper.ntp_error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
error2 = abs(error2);
for (look_ahead = 0; error2 > 0; look_ahead++)
error2 >>= 2;
@@ -564,8 +621,9 @@ static __always_inline int clocksource_b
* Now calculate the error in (1 << look_ahead) ticks, but first
* remove the single look ahead already included in the error.
*/
- tick_error = tick_length >> (NTP_SCALE_SHIFT - clock->shift + 1);
- tick_error -= clock->xtime_interval >> 1;
+ tick_error = tick_length >>
+ (NTP_SCALE_SHIFT - timekeeper.clock->shift + 1);
+ tick_error -= timekeeper.xtime_interval >> 1;
error = ((error - tick_error) >> look_ahead) + tick_error;

/* Finally calculate the adjustment shift value. */
@@ -590,18 +648,19 @@ static __always_inline int clocksource_b
* this is optimized for the most common adjustments of -1,0,1,
* for other values we can do a bit more work.
*/
-static void clocksource_adjust(s64 offset)
+static void timekeeping_adjust(s64 offset)
{
- s64 error, interval = clock->cycle_interval;
+ s64 error, interval = timekeeper.cycle_interval;
int adj;

- error = clock->error >> (NTP_SCALE_SHIFT - clock->shift - 1);
+ error = timekeeper.ntp_error >>
+ (NTP_SCALE_SHIFT - timekeeper.clock->shift - 1);
if (error > interval) {
error >>= 2;
if (likely(error <= interval))
adj = 1;
else
- adj = clocksource_bigadjust(error, &interval, &offset);
+ adj = timekeeping_bigadjust(error, &interval, &offset);
} else if (error < -interval) {
error >>= 2;
if (likely(error >= -interval)) {
@@ -609,15 +668,15 @@ static void clocksource_adjust(s64 offse
interval = -interval;
offset = -offset;
} else
- adj = clocksource_bigadjust(error, &interval, &offset);
+ adj = timekeeping_bigadjust(error, &interval, &offset);
} else
return;

- clock->mult += adj;
- clock->xtime_interval += interval;
- clock->xtime_nsec -= offset;
- clock->error -= (interval - offset) <<
- (NTP_SCALE_SHIFT - clock->shift);
+ timekeeper.clock->mult += adj;
+ timekeeper.xtime_interval += interval;
+ timekeeper.xtime_nsec -= offset;
+ timekeeper.ntp_error -= (interval - offset) <<
+ (NTP_SCALE_SHIFT - timekeeper.clock->shift);
}

/**
@@ -627,53 +686,57 @@ static void clocksource_adjust(s64 offse
*/
void update_wall_time(void)
{
+ struct clocksource *clock;
cycle_t offset;
+ s64 nsecs;

/* Make sure we're fully resumed: */
if (unlikely(timekeeping_suspended))
return;

+ clock = timekeeper.clock;
#ifdef CONFIG_GENERIC_TIME
offset = (clock->read(clock) - clock->cycle_last) & clock->mask;
#else
- offset = clock->cycle_interval;
+ offset = timekeeper.cycle_interval;
#endif
- clock->xtime_nsec = (s64)xtime.tv_nsec << clock->shift;
+ timekeeper.xtime_nsec = (s64)xtime.tv_nsec << clock->shift;

/* normally this loop will run just once, however in the
* case of lost or late ticks, it will accumulate correctly.
*/
- while (offset >= clock->cycle_interval) {
+ while (offset >= timekeeper.cycle_interval) {
/* accumulate one interval */
- offset -= clock->cycle_interval;
- clock->cycle_last += clock->cycle_interval;
+ offset -= timekeeper.cycle_interval;
+ clock->cycle_last += timekeeper.cycle_interval;

- clock->xtime_nsec += clock->xtime_interval;
- if (clock->xtime_nsec >= (u64)NSEC_PER_SEC << clock->shift) {
- clock->xtime_nsec -= (u64)NSEC_PER_SEC << clock->shift;
+ timekeeper.xtime_nsec += timekeeper.xtime_interval;
+ if (timekeeper.xtime_nsec >= (u64)NSEC_PER_SEC << clock->shift) {
+ timekeeper.xtime_nsec -= (u64)NSEC_PER_SEC << clock->shift;
xtime.tv_sec++;
second_overflow();
}

- clock->raw_time.tv_nsec += clock->raw_interval;
- if (clock->raw_time.tv_nsec >= NSEC_PER_SEC) {
- clock->raw_time.tv_nsec -= NSEC_PER_SEC;
- clock->raw_time.tv_sec++;
+ raw_time.tv_nsec += timekeeper.raw_interval;
+ if (raw_time.tv_nsec >= NSEC_PER_SEC) {
+ raw_time.tv_nsec -= NSEC_PER_SEC;
+ raw_time.tv_sec++;
}

/* accumulate error between NTP and clock interval */
- clock->error += tick_length;
- clock->error -= clock->xtime_interval << (NTP_SCALE_SHIFT - clock->shift);
+ timekeeper.ntp_error += tick_length;
+ timekeeper.ntp_error -= timekeeper.xtime_interval <<
+ (NTP_SCALE_SHIFT - clock->shift);
}

/* correct the clock when NTP error is too big */
- clocksource_adjust(offset);
+ timekeeping_adjust(offset);

/*
* Since in the loop above, we accumulate any amount of time
* in xtime_nsec over a second into xtime.tv_sec, its possible for
* xtime_nsec to be fairly small after the loop. Further, if we're
- * slightly speeding the clocksource up in clocksource_adjust(),
+ * slightly speeding the clocksource up in timekeeping_adjust(),
* its possible the required corrective factor to xtime_nsec could
* cause it to underflow.
*
@@ -685,24 +748,26 @@ void update_wall_time(void)
* We'll correct this error next time through this function, when
* xtime_nsec is not as small.
*/
- if (unlikely((s64)clock->xtime_nsec < 0)) {
- s64 neg = -(s64)clock->xtime_nsec;
- clock->xtime_nsec = 0;
- clock->error += neg << (NTP_SCALE_SHIFT - clock->shift);
+ if (unlikely((s64)timekeeper.xtime_nsec < 0)) {
+ s64 neg = -(s64)timekeeper.xtime_nsec;
+ timekeeper.xtime_nsec = 0;
+ timekeeper.ntp_error += neg << (NTP_SCALE_SHIFT - clock->shift);
}

/* store full nanoseconds into xtime after rounding it up and
* add the remainder to the error difference.
*/
- xtime.tv_nsec = ((s64)clock->xtime_nsec >> clock->shift) + 1;
- clock->xtime_nsec -= (s64)xtime.tv_nsec << clock->shift;
- clock->error += clock->xtime_nsec << (NTP_SCALE_SHIFT - clock->shift);
+ xtime.tv_nsec = ((s64)timekeeper.xtime_nsec >> clock->shift) + 1;
+ timekeeper.xtime_nsec -= (s64)xtime.tv_nsec << clock->shift;
+ timekeeper.ntp_error += timekeeper.xtime_nsec <<
+ (NTP_SCALE_SHIFT - clock->shift);

- update_xtime_cache(cyc2ns(clock, offset));
+ nsecs = clocksource_cyc2ns(offset, clock->mult, clock->shift);
+ update_xtime_cache(nsecs);

/* check to see if there is a new clocksource to use */
change_clocksource();
- update_vsyscall(&xtime, clock);
+ update_vsyscall(&xtime, timekeeper.clock);
}

/**