> +#ifdef CONFIG_NO_IDLE_HZ
> +/**
> + * hrtimer_get_next - get next hrtimer to expire
> + *
> + * @bases: ktimer base array
> + */
> +static inline struct hrtimer *hrtimer_get_next(struct hrtimer_base *bases)
> +{
> + unsigned long flags;
> + struct hrtimer *timer = NULL;
> + int i;
> +
> + for (i = 0; i < MAX_HRTIMER_BASES; i++) {
> + struct hrtimer_base *base;
> + struct hrtimer *cur;
> +
> + base = &bases[i];
> + spin_lock_irqsave(&base->lock, flags);
> + cur = rb_entry(base->first, struct hrtimer, node);
> + spin_unlock_irqrestore(&base->lock, flags);
> +
> + if (cur == NULL)
> + continue;
> +
> + if (timer == NULL || cur->expires.tv64 < timer->expires.tv64)
> + timer = cur;
> + }
> +
> + return timer;
> +}
This is racy on SMP. nanosleep hrtimers are on the stack and can go away
due to a signal. posix timers can be removed and destroyed on another
CPU.
Also the expires fields of CLOCK_MONOTONIC and CLOCK_REALTIME based
tiemrs can not really be compared. Expiry value is absolute time of the
respective base clock.
> +/**
> + * ktime_to_jiffies - converts ktime to jiffies
> + *
> + * @event: ktime event to be converted to jiffies
> + *
> + * Caller must take care of xtime locking.
> + */
> +static inline unsigned long ktime_to_jiffies(const ktime_t event)
> +{
> + ktime_t now, delta;
> +
> + now = timespec_to_ktime(xtime);
> + delta = ktime_sub(event, now);
> +
> + return jiffies + (((delta.tv64 * NSEC_CONVERSION) >>
> + (NSEC_JIFFIE_SC - SEC_JIFFIE_SC)) >> SEC_JIFFIE_SC);
> +}
Only CLOCK_REALTIME based timers are based on xtime. For CLOCK_MONOTONIC
based timers this calculation is off by wall_to_monotonic.
> +/**
> + * hrtimer_next_jiffie - get next hrtimer event in jiffies
> + *
> + * Called from next_timer_interrupt() to get the next hrtimer event.
> + * Eventually we should change next_timer_interrupt() to return
> + * results in nanoseconds instead of jiffies. Caller must host xtime_lock.
S390 does not hold xtime lock when calling next_timer_interrupt !
I look for a sane solution.
tglx
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