sched_clock: prevent scd->clock from moving backwards, take #2

[karo-tx-linux.git] / kernel / time / timekeeping.c

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 2d6087c7cf9820fb4a16c43fdd75ed9f33d16bca..4220a2e1faab0144bff2b3d6fd515551ca92451a 100644 (file)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -46,6 +46,9 @@ struct timespec xtime __attribute__ ((aligned (16)));
 struct timespec wall_to_monotonic __attribute__ ((aligned (16)));
 static unsigned long total_sleep_time;         /* seconds */
 
+/* flag for if timekeeping is suspended */
+int __read_mostly timekeeping_suspended;
+
 static struct timespec xtime_cache __attribute__ ((aligned (16)));
 void update_xtime_cache(u64 nsec)
 {
@@ -53,7 +56,7 @@ void update_xtime_cache(u64 nsec)
        timespec_add_ns(&xtime_cache, nsec);
 }
 
-static struct clocksource *clock; /* pointer to current clocksource */
+struct clocksource *clock;
 
 
 #ifdef CONFIG_GENERIC_TIME
@@ -92,6 +95,8 @@ void getnstimeofday(struct timespec *ts)
        unsigned long seq;
        s64 nsecs;
 
+       WARN_ON(timekeeping_suspended);
+
        do {
                seq = read_seqbegin(&xtime_lock);
 
@@ -246,7 +251,7 @@ void __init timekeeping_init(void)
 
        write_seqlock_irqsave(&xtime_lock, flags);
 
-       ntp_clear();
+       ntp_init();
 
        clock = clocksource_get_next();
        clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
@@ -261,8 +266,6 @@ void __init timekeeping_init(void)
        write_sequnlock_irqrestore(&xtime_lock, flags);
 }
 
-/* flag for if timekeeping is suspended */
-static int timekeeping_suspended;
 /* time in seconds when suspend began */
 static unsigned long timekeeping_suspend_time;
 /* xtime offset when we went into suspend */
@@ -371,7 +374,7 @@ static __always_inline int clocksource_bigadjust(s64 error, s64 *interval,
         * 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 >> (TICK_LENGTH_SHIFT + 22 - 2 * SHIFT_HZ);
+       error2 = clock->error >> (NTP_SCALE_SHIFT + 22 - 2 * SHIFT_HZ);
        error2 = abs(error2);
        for (look_ahead = 0; error2 > 0; look_ahead++)
                error2 >>= 2;
@@ -380,8 +383,7 @@ static __always_inline int clocksource_bigadjust(s64 error, s64 *interval,
         * Now calculate the error in (1 << look_ahead) ticks, but first
         * remove the single look ahead already included in the error.
         */
-       tick_error = current_tick_length() >>
-               (TICK_LENGTH_SHIFT - clock->shift + 1);
+       tick_error = tick_length >> (NTP_SCALE_SHIFT - clock->shift + 1);
        tick_error -= clock->xtime_interval >> 1;
        error = ((error - tick_error) >> look_ahead) + tick_error;
 
@@ -412,7 +414,7 @@ static void clocksource_adjust(s64 offset)
        s64 error, interval = clock->cycle_interval;
        int adj;
 
-       error = clock->error >> (TICK_LENGTH_SHIFT - clock->shift - 1);
+       error = clock->error >> (NTP_SCALE_SHIFT - clock->shift - 1);
        if (error > interval) {
                error >>= 2;
                if (likely(error <= interval))
@@ -434,7 +436,7 @@ static void clocksource_adjust(s64 offset)
        clock->xtime_interval += interval;
        clock->xtime_nsec -= offset;
        clock->error -= (interval - offset) <<
-                       (TICK_LENGTH_SHIFT - clock->shift);
+                       (NTP_SCALE_SHIFT - clock->shift);
 }
 
 /**
@@ -473,8 +475,8 @@ void update_wall_time(void)
                }
 
                /* accumulate error between NTP and clock interval */
-               clock->error += current_tick_length();
-               clock->error -= clock->xtime_interval << (TICK_LENGTH_SHIFT - clock->shift);
+               clock->error += tick_length;
+               clock->error -= clock->xtime_interval << (NTP_SCALE_SHIFT - clock->shift);
        }
 
        /* correct the clock when NTP error is too big */