diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/time/clocksource.c | 126 | ||||
| -rw-r--r-- | kernel/timer.c | 45 |
2 files changed, 144 insertions, 27 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 2f6a3d6e43bc..3cb8ac978270 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -63,9 +63,116 @@ static int __init clocksource_done_booting(void) finished_booting = 1; return 0; } - late_initcall(clocksource_done_booting); +#ifdef CONFIG_CLOCKSOURCE_WATCHDOG +static LIST_HEAD(watchdog_list); +static struct clocksource *watchdog; +static struct timer_list watchdog_timer; +static DEFINE_SPINLOCK(watchdog_lock); +static cycle_t watchdog_last; +/* + * Interval: 0.5sec Treshold: 0.0625s + */ +#define WATCHDOG_INTERVAL (HZ >> 1) +#define WATCHDOG_TRESHOLD (NSEC_PER_SEC >> 4) + +static void clocksource_ratewd(struct clocksource *cs, int64_t delta) +{ + if (delta > -WATCHDOG_TRESHOLD && delta < WATCHDOG_TRESHOLD) + return; + + printk(KERN_WARNING "Clocksource %s unstable (delta = %Ld ns)\n", + cs->name, delta); + cs->flags &= ~(CLOCK_SOURCE_VALID_FOR_HRES | CLOCK_SOURCE_WATCHDOG); + clocksource_change_rating(cs, 0); + cs->flags &= ~CLOCK_SOURCE_WATCHDOG; + list_del(&cs->wd_list); +} + +static void clocksource_watchdog(unsigned long data) +{ + struct clocksource *cs, *tmp; + cycle_t csnow, wdnow; + int64_t wd_nsec, cs_nsec; + + spin_lock(&watchdog_lock); + + wdnow = watchdog->read(); + wd_nsec = cyc2ns(watchdog, (wdnow - watchdog_last) & watchdog->mask); + watchdog_last = wdnow; + + list_for_each_entry_safe(cs, tmp, &watchdog_list, wd_list) { + csnow = cs->read(); + /* Initialized ? */ + if (!(cs->flags & CLOCK_SOURCE_WATCHDOG)) { + if ((cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) && + (watchdog->flags & CLOCK_SOURCE_IS_CONTINUOUS)) { + cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; + } + cs->flags |= CLOCK_SOURCE_WATCHDOG; + cs->wd_last = csnow; + } else { + cs_nsec = cyc2ns(cs, (csnow - cs->wd_last) & cs->mask); + cs->wd_last = csnow; + /* Check the delta. Might remove from the list ! */ + clocksource_ratewd(cs, cs_nsec - wd_nsec); + } + } + + if (!list_empty(&watchdog_list)) { + __mod_timer(&watchdog_timer, + watchdog_timer.expires + WATCHDOG_INTERVAL); + } + spin_unlock(&watchdog_lock); +} +static void clocksource_check_watchdog(struct clocksource *cs) +{ + struct clocksource *cse; + unsigned long flags; + + spin_lock_irqsave(&watchdog_lock, flags); + if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) { + int started = !list_empty(&watchdog_list); + + list_add(&cs->wd_list, &watchdog_list); + if (!started && watchdog) { + watchdog_last = watchdog->read(); + watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL; + add_timer(&watchdog_timer); + } + } else if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) { + cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; + + if (!watchdog || cs->rating > watchdog->rating) { + if (watchdog) + del_timer(&watchdog_timer); + watchdog = cs; + init_timer(&watchdog_timer); + watchdog_timer.function = clocksource_watchdog; + + /* Reset watchdog cycles */ + list_for_each_entry(cse, &watchdog_list, wd_list) + cse->flags &= ~CLOCK_SOURCE_WATCHDOG; + /* Start if list is not empty */ + if (!list_empty(&watchdog_list)) { + watchdog_last = watchdog->read(); + watchdog_timer.expires = + jiffies + WATCHDOG_INTERVAL; + add_timer(&watchdog_timer); + } + } + } + spin_unlock_irqrestore(&watchdog_lock, flags); +} +#else +static void clocksource_check_watchdog(struct clocksource *cs) +{ + if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS) + cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES; +} +#endif + /** * clocksource_get_next - Returns the selected clocksource * @@ -94,13 +201,21 @@ struct clocksource *clocksource_get_next(void) */ static struct clocksource *select_clocksource(void) { + struct clocksource *next; + if (list_empty(&clocksource_list)) return NULL; if (clocksource_override) - return clocksource_override; + next = clocksource_override; + else + next = list_entry(clocksource_list.next, struct clocksource, + list); - return list_entry(clocksource_list.next, struct clocksource, list); + if (next == curr_clocksource) + return NULL; + + return next; } /* @@ -138,13 +253,15 @@ static int clocksource_enqueue(struct clocksource *c) int clocksource_register(struct clocksource *c) { unsigned long flags; - int ret = 0; + int ret; spin_lock_irqsave(&clocksource_lock, flags); ret = clocksource_enqueue(c); if (!ret) next_clocksource = select_clocksource(); spin_unlock_irqrestore(&clocksource_lock, flags); + if (!ret) + clocksource_check_watchdog(c); return ret; } EXPORT_SYMBOL(clocksource_register); @@ -159,6 +276,7 @@ void clocksource_change_rating(struct clocksource *cs, int rating) spin_lock_irqsave(&clocksource_lock, flags); list_del(&cs->list); + cs->rating = rating; clocksource_enqueue(cs); next_clocksource = select_clocksource(); spin_unlock_irqrestore(&clocksource_lock, flags); diff --git a/kernel/timer.c b/kernel/timer.c index 4b088fcadb3f..b68a21a82e17 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -832,30 +832,33 @@ EXPORT_SYMBOL(do_settimeofday); * * 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; + + 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 @@ int timekeeping_is_continuous(void) 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 @@ static void update_wall_time(void) 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(); } /* |