diff options
| -rw-r--r-- | kernel/time/hrtimer.c | 87 |
1 files changed, 59 insertions, 28 deletions
diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 7ebf642b53f9..214fd65a9597 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -739,23 +739,7 @@ static inline int hrtimer_is_hres_enabled(void) return hrtimer_hres_enabled; } -/* - * Retrigger next event is called after clock was set - * - * Called with interrupts disabled via on_each_cpu() - */ -static void retrigger_next_event(void *arg) -{ - struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases); - - if (!__hrtimer_hres_active(base)) - return; - - raw_spin_lock(&base->lock); - hrtimer_update_base(base); - hrtimer_force_reprogram(base, 0); - raw_spin_unlock(&base->lock); -} +static void retrigger_next_event(void *arg); /* * Switch to high resolution mode @@ -781,9 +765,50 @@ static void hrtimer_switch_to_hres(void) static inline int hrtimer_is_hres_enabled(void) { return 0; } static inline void hrtimer_switch_to_hres(void) { } -static inline void retrigger_next_event(void *arg) { } #endif /* CONFIG_HIGH_RES_TIMERS */ +/* + * Retrigger next event is called after clock was set with interrupts + * disabled through an SMP function call or directly from low level + * resume code. + * + * This is only invoked when: + * - CONFIG_HIGH_RES_TIMERS is enabled. + * - CONFIG_NOHZ_COMMON is enabled + * + * For the other cases this function is empty and because the call sites + * are optimized out it vanishes as well, i.e. no need for lots of + * #ifdeffery. + */ +static void retrigger_next_event(void *arg) +{ + struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases); + + /* + * When high resolution mode or nohz is active, then the offsets of + * CLOCK_REALTIME/TAI/BOOTTIME have to be updated. Otherwise the + * next tick will take care of that. + * + * If high resolution mode is active then the next expiring timer + * must be reevaluated and the clock event device reprogrammed if + * necessary. + * + * In the NOHZ case the update of the offset and the reevaluation + * of the next expiring timer is enough. The return from the SMP + * function call will take care of the reprogramming in case the + * CPU was in a NOHZ idle sleep. + */ + if (!__hrtimer_hres_active(base) && !tick_nohz_active) + return; + + raw_spin_lock(&base->lock); + hrtimer_update_base(base); + if (__hrtimer_hres_active(base)) + hrtimer_force_reprogram(base, 0); + else + hrtimer_update_next_event(base); + raw_spin_unlock(&base->lock); +} /* * When a timer is enqueued and expires earlier than the already enqueued @@ -842,22 +867,28 @@ static void hrtimer_reprogram(struct hrtimer *timer, bool reprogram) } /* - * Clock realtime was set - * - * Change the offset of the realtime clock vs. the monotonic - * clock. + * Clock was set. This might affect CLOCK_REALTIME, CLOCK_TAI and + * CLOCK_BOOTTIME (for late sleep time injection). * - * We might have to reprogram the high resolution timer interrupt. On - * SMP we call the architecture specific code to retrigger _all_ high - * resolution timer interrupts. On UP we just disable interrupts and - * call the high resolution interrupt code. + * This requires to update the offsets for these clocks + * vs. CLOCK_MONOTONIC. When high resolution timers are enabled, then this + * also requires to eventually reprogram the per CPU clock event devices + * when the change moves an affected timer ahead of the first expiring + * timer on that CPU. Obviously remote per CPU clock event devices cannot + * be reprogrammed. The other reason why an IPI has to be sent is when the + * system is in !HIGH_RES and NOHZ mode. The NOHZ mode updates the offsets + * in the tick, which obviously might be stopped, so this has to bring out + * the remote CPU which might sleep in idle to get this sorted. */ void clock_was_set(void) { -#ifdef CONFIG_HIGH_RES_TIMERS + if (!hrtimer_hres_active() && !tick_nohz_active) + goto out_timerfd; + /* Retrigger the CPU local events everywhere */ on_each_cpu(retrigger_next_event, NULL, 1); -#endif + +out_timerfd: timerfd_clock_was_set(); } |