select: Introduce a hrtimeout function (7bb67439) · Commits · 戴 / test

include/linux/hrtimer.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -346,6 +346,8 @@ extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
		extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
		struct task_struct *tsk);

		extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);

		/* Soft interrupt function to run the hrtimer queues: */
		extern void hrtimer_run_queues(void);
		extern void hrtimer_run_pending(void);

kernel/hrtimer.c

+65 −0

Original line number	Diff line number	Diff line
		@@ -1678,3 +1678,68 @@ void __init hrtimers_init(void)
		#endif
		}

		/**
		* schedule_hrtimeout - sleep until timeout
		* @expires: timeout value (ktime_t)
		* @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
		*
		* Make the current task sleep until the given expiry time has
		* elapsed. The routine will return immediately unless
		* the current task state has been set (see set_current_state()).
		*
		* You can set the task state as follows -
		*
		* %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
		* pass before the routine returns.
		*
		* %TASK_INTERRUPTIBLE - the routine may return early if a signal is
		* delivered to the current task.
		*
		* The current task state is guaranteed to be TASK_RUNNING when this
		* routine returns.
		*
		* Returns 0 when the timer has expired otherwise -EINTR
		*/
		int __sched schedule_hrtimeout(ktime_t *expires,
		const enum hrtimer_mode mode)
		{
		struct hrtimer_sleeper t;

		/*
		* Optimize when a zero timeout value is given. It does not
		* matter whether this is an absolute or a relative time.
		*/
		if (expires && !expires->tv64) {
		__set_current_state(TASK_RUNNING);
		return 0;
		}

		/*
		* A NULL parameter means "inifinte"
		*/
		if (!expires) {
		schedule();
		__set_current_state(TASK_RUNNING);
		return -EINTR;
		}

		hrtimer_init_on_stack(&t.timer, CLOCK_MONOTONIC, mode);
		t.timer.expires = *expires;

		hrtimer_init_sleeper(&t, current);

		hrtimer_start(&t.timer, t.timer.expires, mode);
		if (!hrtimer_active(&t.timer))
		t.task = NULL;

		if (likely(t.task))
		schedule();

		hrtimer_cancel(&t.timer);
		destroy_hrtimer_on_stack(&t.timer);

		__set_current_state(TASK_RUNNING);

		return !t.task ? 0 : -EINTR;
		}
		EXPORT_SYMBOL_GPL(schedule_hrtimeout);

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