[PATCH] clocksource: Add verification (watchdog) helper
The TSC needs to be verified against another clocksource. Instead of using
hardwired assumptions of available hardware, provide a generic verification
mechanism. The verification uses the best available clocksource and handles
the usability for high resolution timers / dynticks of the clocksource which
needs to be verified.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/timer.c b/kernel/timer.c
index 4b088fc..b68a21a 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -832,30 +832,33 @@
*
* Accumulates current time interval and initializes new clocksource
*/
-static int change_clocksource(void)
+static void change_clocksource(void)
{
struct clocksource *new;
cycle_t now;
u64 nsec;
- new = clocksource_get_next();
- if (clock != new) {
- now = clocksource_read(new);
- nsec = __get_nsec_offset();
- timespec_add_ns(&xtime, nsec);
- clock = new;
- clock->cycle_last = now;
- printk(KERN_INFO "Time: %s clocksource has been installed.\n",
- clock->name);
- return 1;
- }
- return 0;
+ new = clocksource_get_next();
+
+ if (clock == new)
+ return;
+
+ now = clocksource_read(new);
+ nsec = __get_nsec_offset();
+ timespec_add_ns(&xtime, nsec);
+
+ clock = new;
+ clock->cycle_last = now;
+
+ clock->error = 0;
+ clock->xtime_nsec = 0;
+ clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
+
+ printk(KERN_INFO "Time: %s clocksource has been installed.\n",
+ clock->name);
}
#else
-static inline int change_clocksource(void)
-{
- return 0;
-}
+static inline void change_clocksource(void) { }
#endif
/**
@@ -869,7 +872,7 @@
do {
seq = read_seqbegin(&xtime_lock);
- ret = clock->flags & CLOCK_SOURCE_IS_CONTINUOUS;
+ ret = clock->flags & CLOCK_SOURCE_VALID_FOR_HRES;
} while (read_seqretry(&xtime_lock, seq));
@@ -1124,11 +1127,7 @@
clock->xtime_nsec -= (s64)xtime.tv_nsec << clock->shift;
/* check to see if there is a new clocksource to use */
- if (change_clocksource()) {
- clock->error = 0;
- clock->xtime_nsec = 0;
- clocksource_calculate_interval(clock, NTP_INTERVAL_LENGTH);
- }
+ change_clocksource();
}
/*
