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: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

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: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Arjan van de Ven
1 parent 70bb08962e
Showing 2 changed files with 67 additions and 0 deletions Side-by-side Diff
include/linux/hrtimer.h
kernel/hrtimer.c
@@ -346,6 +346,8 @@
 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);
@@ -1677,4 +1677,70 @@
 	open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq);
 #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);
...	...	@@ -346,6 +346,8 @@
346	346	extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
347	347	struct task_struct *tsk);
348	348
	349	+extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
	350	+
349	351	/* Soft interrupt function to run the hrtimer queues: */
350	352	extern void hrtimer_run_queues(void);
351	353	extern void hrtimer_run_pending(void);
...	...	@@ -1677,4 +1677,70 @@
1677	1677	open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq);
1678	1678	#endif
1679	1679	}
	1680	+
	1681	+/**
	1682	+ * schedule_hrtimeout - sleep until timeout
	1683	+ * @expires: timeout value (ktime_t)
	1684	+ * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
	1685	+ *
	1686	+ * Make the current task sleep until the given expiry time has
	1687	+ * elapsed. The routine will return immediately unless
	1688	+ * the current task state has been set (see set_current_state()).
	1689	+ *
	1690	+ * You can set the task state as follows -
	1691	+ *
	1692	+ * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
	1693	+ * pass before the routine returns.
	1694	+ *
	1695	+ * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
	1696	+ * delivered to the current task.
	1697	+ *
	1698	+ * The current task state is guaranteed to be TASK_RUNNING when this
	1699	+ * routine returns.
	1700	+ *
	1701	+ * Returns 0 when the timer has expired otherwise -EINTR
	1702	+ */
	1703	+int __sched schedule_hrtimeout(ktime_t *expires,
	1704	+ const enum hrtimer_mode mode)
	1705	+{
	1706	+ struct hrtimer_sleeper t;
	1707	+
	1708	+ /*
	1709	+ * Optimize when a zero timeout value is given. It does not
	1710	+ * matter whether this is an absolute or a relative time.
	1711	+ */
	1712	+ if (expires && !expires->tv64) {
	1713	+ __set_current_state(TASK_RUNNING);
	1714	+ return 0;
	1715	+ }
	1716	+
	1717	+ /*
	1718	+ * A NULL parameter means "inifinte"
	1719	+ */
	1720	+ if (!expires) {
	1721	+ schedule();
	1722	+ __set_current_state(TASK_RUNNING);
	1723	+ return -EINTR;
	1724	+ }
	1725	+
	1726	+ hrtimer_init_on_stack(&t.timer, CLOCK_MONOTONIC, mode);
	1727	+ t.timer.expires = *expires;
	1728	+
	1729	+ hrtimer_init_sleeper(&t, current);
	1730	+
	1731	+ hrtimer_start(&t.timer, t.timer.expires, mode);
	1732	+ if (!hrtimer_active(&t.timer))
	1733	+ t.task = NULL;
	1734	+
	1735	+ if (likely(t.task))
	1736	+ schedule();
	1737	+
	1738	+ hrtimer_cancel(&t.timer);
	1739	+ destroy_hrtimer_on_stack(&t.timer);
	1740	+
	1741	+ __set_current_state(TASK_RUNNING);
	1742	+
	1743	+ return !t.task ? 0 : -EINTR;
	1744	+}
	1745	+EXPORT_SYMBOL_GPL(schedule_hrtimeout);