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Commit 7bb67439 authored by Arjan van de Ven's avatar Arjan van de Ven
Browse files

select: Introduce a hrtimeout function 



This patch adds a schedule_hrtimeout() function, to be used by select() and
poll() in a later patch. This function works similar to schedule_timeout()
in most ways, but takes a timespec rather than jiffies.

With a lot of contributions/fixes from Thomas

Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 70bb0896

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);