X-Git-Url: https://nv-tegra.nvidia.com/r/gitweb?p=linux-2.6.git;a=blobdiff_plain;f=kernel%2Fhrtimer.c;h=0086628b6e9772b675ee5cd9bbd37d4b4d035534;hp=42672790ee13ad8bf234ce5191f4145a737c8a1b;hb=d4bb527438b4181cd3c564ae04dd344c381283a1;hpb=d3f6302e7e51b41af86c6496ffb2f95e8f2179df diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index 42672790ee1..0086628b6e9 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -127,11 +127,11 @@ struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer, for (;;) { base = timer->base; if (likely(base != NULL)) { - spin_lock_irqsave(&base->cpu_base->lock, *flags); + raw_spin_lock_irqsave(&base->cpu_base->lock, *flags); if (likely(base == timer->base)) return base; /* The timer has migrated to another CPU: */ - spin_unlock_irqrestore(&base->cpu_base->lock, *flags); + raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags); } cpu_relax(); } @@ -208,13 +208,13 @@ again: /* See the comment in lock_timer_base() */ timer->base = NULL; - spin_unlock(&base->cpu_base->lock); - spin_lock(&new_base->cpu_base->lock); + raw_spin_unlock(&base->cpu_base->lock); + raw_spin_lock(&new_base->cpu_base->lock); if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) { cpu = this_cpu; - spin_unlock(&new_base->cpu_base->lock); - spin_lock(&base->cpu_base->lock); + raw_spin_unlock(&new_base->cpu_base->lock); + raw_spin_lock(&base->cpu_base->lock); timer->base = base; goto again; } @@ -230,7 +230,7 @@ lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags) { struct hrtimer_clock_base *base = timer->base; - spin_lock_irqsave(&base->cpu_base->lock, *flags); + raw_spin_lock_irqsave(&base->cpu_base->lock, *flags); return base; } @@ -509,13 +509,14 @@ static inline int hrtimer_hres_active(void) * next event * Called with interrupts disabled and base->lock held */ -static void hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base) +static void +hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal) { int i; struct hrtimer_clock_base *base = cpu_base->clock_base; - ktime_t expires; + ktime_t expires, expires_next; - cpu_base->expires_next.tv64 = KTIME_MAX; + expires_next.tv64 = KTIME_MAX; for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) { struct hrtimer *timer; @@ -531,10 +532,15 @@ static void hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base) */ if (expires.tv64 < 0) expires.tv64 = 0; - if (expires.tv64 < cpu_base->expires_next.tv64) - cpu_base->expires_next = expires; + if (expires.tv64 < expires_next.tv64) + expires_next = expires; } + if (skip_equal && expires_next.tv64 == cpu_base->expires_next.tv64) + return; + + cpu_base->expires_next.tv64 = expires_next.tv64; + if (cpu_base->expires_next.tv64 != KTIME_MAX) tick_program_event(cpu_base->expires_next, 1); } @@ -551,7 +557,7 @@ static void hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base) static int hrtimer_reprogram(struct hrtimer *timer, struct hrtimer_clock_base *base) { - ktime_t *expires_next = &__get_cpu_var(hrtimer_bases).expires_next; + struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases); ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset); int res; @@ -576,7 +582,16 @@ static int hrtimer_reprogram(struct hrtimer *timer, if (expires.tv64 < 0) return -ETIME; - if (expires.tv64 >= expires_next->tv64) + if (expires.tv64 >= cpu_base->expires_next.tv64) + return 0; + + /* + * If a hang was detected in the last timer interrupt then we + * do not schedule a timer which is earlier than the expiry + * which we enforced in the hang detection. We want the system + * to make progress. + */ + if (cpu_base->hang_detected) return 0; /* @@ -584,7 +599,7 @@ static int hrtimer_reprogram(struct hrtimer *timer, */ res = tick_program_event(expires, 0); if (!IS_ERR_VALUE(res)) - *expires_next = expires; + cpu_base->expires_next = expires; return res; } @@ -613,12 +628,12 @@ static void retrigger_next_event(void *arg) base = &__get_cpu_var(hrtimer_bases); /* Adjust CLOCK_REALTIME offset */ - spin_lock(&base->lock); + raw_spin_lock(&base->lock); base->clock_base[CLOCK_REALTIME].offset = timespec_to_ktime(realtime_offset); - hrtimer_force_reprogram(base); - spin_unlock(&base->lock); + hrtimer_force_reprogram(base, 0); + raw_spin_unlock(&base->lock); } /* @@ -679,9 +694,9 @@ static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer, { if (base->cpu_base->hres_active && hrtimer_reprogram(timer, base)) { if (wakeup) { - spin_unlock(&base->cpu_base->lock); + raw_spin_unlock(&base->cpu_base->lock); raise_softirq_irqoff(HRTIMER_SOFTIRQ); - spin_lock(&base->cpu_base->lock); + raw_spin_lock(&base->cpu_base->lock); } else __raise_softirq_irqoff(HRTIMER_SOFTIRQ); @@ -728,7 +743,8 @@ static int hrtimer_switch_to_hres(void) static inline int hrtimer_hres_active(void) { return 0; } static inline int hrtimer_is_hres_enabled(void) { return 0; } static inline int hrtimer_switch_to_hres(void) { return 0; } -static inline void hrtimer_force_reprogram(struct hrtimer_cpu_base *base) { } +static inline void +hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { } static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer, struct hrtimer_clock_base *base, int wakeup) @@ -740,17 +756,33 @@ static inline void hrtimer_init_timer_hres(struct hrtimer *timer) { } #endif /* CONFIG_HIGH_RES_TIMERS */ -#ifdef CONFIG_TIMER_STATS -void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer, void *addr) +static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer) { +#ifdef CONFIG_TIMER_STATS if (timer->start_site) return; - - timer->start_site = addr; + timer->start_site = __builtin_return_address(0); memcpy(timer->start_comm, current->comm, TASK_COMM_LEN); timer->start_pid = current->pid; +#endif +} + +static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer) +{ +#ifdef CONFIG_TIMER_STATS + timer->start_site = NULL; +#endif } + +static inline void timer_stats_account_hrtimer(struct hrtimer *timer) +{ +#ifdef CONFIG_TIMER_STATS + if (likely(!timer_stats_active)) + return; + timer_stats_update_stats(timer, timer->start_pid, timer->start_site, + timer->function, timer->start_comm, 0); #endif +} /* * Counterpart to lock_hrtimer_base above: @@ -758,7 +790,7 @@ void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer, void *addr) static inline void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags) { - spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags); + raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags); } /** @@ -871,19 +903,29 @@ static void __remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, unsigned long newstate, int reprogram) { - if (timer->state & HRTIMER_STATE_ENQUEUED) { - /* - * Remove the timer from the rbtree and replace the - * first entry pointer if necessary. - */ - if (base->first == &timer->node) { - base->first = rb_next(&timer->node); - /* Reprogram the clock event device. if enabled */ - if (reprogram && hrtimer_hres_active()) - hrtimer_force_reprogram(base->cpu_base); + if (!(timer->state & HRTIMER_STATE_ENQUEUED)) + goto out; + + /* + * Remove the timer from the rbtree and replace the first + * entry pointer if necessary. + */ + if (base->first == &timer->node) { + base->first = rb_next(&timer->node); +#ifdef CONFIG_HIGH_RES_TIMERS + /* Reprogram the clock event device. if enabled */ + if (reprogram && hrtimer_hres_active()) { + ktime_t expires; + + expires = ktime_sub(hrtimer_get_expires(timer), + base->offset); + if (base->cpu_base->expires_next.tv64 == expires.tv64) + hrtimer_force_reprogram(base->cpu_base, 1); } - rb_erase(&timer->node, &base->active); +#endif } + rb_erase(&timer->node, &base->active); +out: timer->state = newstate; } @@ -1081,7 +1123,7 @@ ktime_t hrtimer_get_next_event(void) unsigned long flags; int i; - spin_lock_irqsave(&cpu_base->lock, flags); + raw_spin_lock_irqsave(&cpu_base->lock, flags); if (!hrtimer_hres_active()) { for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) { @@ -1098,7 +1140,7 @@ ktime_t hrtimer_get_next_event(void) } } - spin_unlock_irqrestore(&cpu_base->lock, flags); + raw_spin_unlock_irqrestore(&cpu_base->lock, flags); if (mindelta.tv64 < 0) mindelta.tv64 = 0; @@ -1180,11 +1222,11 @@ static void __run_hrtimer(struct hrtimer *timer, ktime_t *now) * they get migrated to another cpu, therefore its safe to unlock * the timer base. */ - spin_unlock(&cpu_base->lock); + raw_spin_unlock(&cpu_base->lock); trace_hrtimer_expire_entry(timer, now); restart = fn(timer); trace_hrtimer_expire_exit(timer); - spin_lock(&cpu_base->lock); + raw_spin_lock(&cpu_base->lock); /* * Note: We clear the CALLBACK bit after enqueue_hrtimer and @@ -1200,29 +1242,6 @@ static void __run_hrtimer(struct hrtimer *timer, ktime_t *now) #ifdef CONFIG_HIGH_RES_TIMERS -static int force_clock_reprogram; - -/* - * After 5 iteration's attempts, we consider that hrtimer_interrupt() - * is hanging, which could happen with something that slows the interrupt - * such as the tracing. Then we force the clock reprogramming for each future - * hrtimer interrupts to avoid infinite loops and use the min_delta_ns - * threshold that we will overwrite. - * The next tick event will be scheduled to 3 times we currently spend on - * hrtimer_interrupt(). This gives a good compromise, the cpus will spend - * 1/4 of their time to process the hrtimer interrupts. This is enough to - * let it running without serious starvation. - */ - -static inline void -hrtimer_interrupt_hanging(struct clock_event_device *dev, - ktime_t try_time) -{ - force_clock_reprogram = 1; - dev->min_delta_ns = (unsigned long)try_time.tv64 * 3; - printk(KERN_WARNING "hrtimer: interrupt too slow, " - "forcing clock min delta to %lu ns\n", dev->min_delta_ns); -} /* * High resolution timer interrupt * Called with interrupts disabled @@ -1231,24 +1250,18 @@ void hrtimer_interrupt(struct clock_event_device *dev) { struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases); struct hrtimer_clock_base *base; - ktime_t expires_next, now; - int nr_retries = 0; - int i; + ktime_t expires_next, now, entry_time, delta; + int i, retries = 0; BUG_ON(!cpu_base->hres_active); cpu_base->nr_events++; dev->next_event.tv64 = KTIME_MAX; - retry: - /* 5 retries is enough to notice a hang */ - if (!(++nr_retries % 5)) - hrtimer_interrupt_hanging(dev, ktime_sub(ktime_get(), now)); - - now = ktime_get(); - + entry_time = now = ktime_get(); +retry: expires_next.tv64 = KTIME_MAX; - spin_lock(&cpu_base->lock); + raw_spin_lock(&cpu_base->lock); /* * We set expires_next to KTIME_MAX here with cpu_base->lock * held to prevent that a timer is enqueued in our queue via @@ -1304,13 +1317,51 @@ void hrtimer_interrupt(struct clock_event_device *dev) * against it. */ cpu_base->expires_next = expires_next; - spin_unlock(&cpu_base->lock); + raw_spin_unlock(&cpu_base->lock); /* Reprogramming necessary ? */ - if (expires_next.tv64 != KTIME_MAX) { - if (tick_program_event(expires_next, force_clock_reprogram)) - goto retry; + if (expires_next.tv64 == KTIME_MAX || + !tick_program_event(expires_next, 0)) { + cpu_base->hang_detected = 0; + return; } + + /* + * The next timer was already expired due to: + * - tracing + * - long lasting callbacks + * - being scheduled away when running in a VM + * + * We need to prevent that we loop forever in the hrtimer + * interrupt routine. We give it 3 attempts to avoid + * overreacting on some spurious event. + */ + now = ktime_get(); + cpu_base->nr_retries++; + if (++retries < 3) + goto retry; + /* + * Give the system a chance to do something else than looping + * here. We stored the entry time, so we know exactly how long + * we spent here. We schedule the next event this amount of + * time away. + */ + cpu_base->nr_hangs++; + cpu_base->hang_detected = 1; + delta = ktime_sub(now, entry_time); + if (delta.tv64 > cpu_base->max_hang_time.tv64) + cpu_base->max_hang_time = delta; + /* + * Limit it to a sensible value as we enforce a longer + * delay. Give the CPU at least 100ms to catch up. + */ + if (delta.tv64 > 100 * NSEC_PER_MSEC) + expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC); + else + expires_next = ktime_add(now, delta); + tick_program_event(expires_next, 1); + printk_once(KERN_WARNING "hrtimer: interrupt took %llu ns\n", + ktime_to_ns(delta)); } /* @@ -1406,7 +1457,7 @@ void hrtimer_run_queues(void) gettime = 0; } - spin_lock(&cpu_base->lock); + raw_spin_lock(&cpu_base->lock); while ((node = base->first)) { struct hrtimer *timer; @@ -1418,7 +1469,7 @@ void hrtimer_run_queues(void) __run_hrtimer(timer, &base->softirq_time); } - spin_unlock(&cpu_base->lock); + raw_spin_unlock(&cpu_base->lock); } } @@ -1574,7 +1625,7 @@ static void __cpuinit init_hrtimers_cpu(int cpu) struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu); int i; - spin_lock_init(&cpu_base->lock); + raw_spin_lock_init(&cpu_base->lock); for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) cpu_base->clock_base[i].cpu_base = cpu_base; @@ -1632,16 +1683,16 @@ static void migrate_hrtimers(int scpu) * The caller is globally serialized and nobody else * takes two locks at once, deadlock is not possible. */ - spin_lock(&new_base->lock); - spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING); + raw_spin_lock(&new_base->lock); + raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING); for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) { migrate_hrtimer_list(&old_base->clock_base[i], &new_base->clock_base[i]); } - spin_unlock(&old_base->lock); - spin_unlock(&new_base->lock); + raw_spin_unlock(&old_base->lock); + raw_spin_unlock(&new_base->lock); /* Check, if we got expired work to do */ __hrtimer_peek_ahead_timers();