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kernel
os
linux
hrtimer: Update hrtimer->state documentation
We changed some of the state bits and combinations thereof over time,
but never updated the documentation.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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include/linux/hrtimer.h
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include/linux/hrtimer.h
···
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* 0x00 inactive
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* 0x01 enqueued into rbtree
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* 0x02 callback function running
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* 0x04 timer is migrated to another cpu
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*
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* Special cases:
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* 0x03 callback function running and enqueued
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* (was requeued on another CPU)
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* 0x09 timer was migrated on CPU hotunplug
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* 0x05 timer was migrated on CPU hotunplug
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*
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* The "callback function running and enqueued" status is only possible on
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* SMP. It happens for example when a posix timer expired and the callback
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* queued a signal. Between dropping the lock which protects the posix timer
···
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* as otherwise the timer could be removed before the softirq code finishes the
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* the handling of the timer.
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*
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* The HRTIMER_STATE_ENQUEUED bit is always or'ed to the current state to
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* preserve the HRTIMER_STATE_CALLBACK bit in the above scenario.
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* The HRTIMER_STATE_ENQUEUED bit is always or'ed to the current state
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* to preserve the HRTIMER_STATE_CALLBACK in the above scenario. This
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* also affects HRTIMER_STATE_MIGRATE where the preservation is not
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* necessary. HRTIMER_STATE_MIGRATE is cleared after the timer is
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* enqueued on the new cpu.
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*
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* All state transitions are protected by cpu_base->lock.
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*/
···
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extern ktime_t hrtimer_get_next_event(void);
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/*
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* A timer is active, when it is enqueued into the rbtree or the callback
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* function is running.
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* A timer is active, when it is enqueued into the rbtree or the
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* callback function is running or it's in the state of being migrated
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* to another cpu.
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*/
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static inline int hrtimer_active(const struct hrtimer *timer)
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{