[RFC PATCH 1/3] introduce schedule_timeout_hr

[Arnd Bergmann <arnd@arndb.de>]

[-- Attachment #1: add-schedule-timeout-hr.diff --]
[-- Type: text/plain, Size: 2687 bytes --]

The new schedule_timeout_hr function is a variant of schedule_timeout
that uses hrtimers internally. Consequently, its argument and
return value are ktime_t.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Index: linux-cg/include/linux/sched.h
===================================================================
--- linux-cg.orig/include/linux/sched.h
+++ linux-cg/include/linux/sched.h
@@ -246,6 +246,8 @@ extern int in_sched_functions(unsigned l
 
 #define	MAX_SCHEDULE_TIMEOUT	LONG_MAX
 extern signed long FASTCALL(schedule_timeout(signed long timeout));
+extern ktime_t FASTCALL(schedule_timeout_hr(ktime_t timeout));
+
 extern signed long schedule_timeout_interruptible(signed long timeout);
 extern signed long schedule_timeout_uninterruptible(signed long timeout);
 asmlinkage void schedule(void);
Index: linux-cg/kernel/hrtimer.c
===================================================================
--- linux-cg.orig/kernel/hrtimer.c
+++ linux-cg/kernel/hrtimer.c
@@ -1206,6 +1206,54 @@ void hrtimer_init_sleeper(struct hrtimer
 #endif
 }
 
+/**
+ * schedule_timeout_hr - sleep until timeout
+ * @timeout: timeout value
+ *
+ * Make the current task sleep until @timeout 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 is guaranteed to
+ * pass before the routine returns. The routine will return 0
+ *
+ * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
+ * delivered to the current task. In this case the remaining time
+ * in jiffies will be returned, or 0 if the timer expired in time
+ *
+ * The current task state is guaranteed to be TASK_RUNNING when this
+ * routine returns.
+ *
+ * In all cases the return value is guaranteed to be a non-negative
+ * time value.
+ */
+static ktime_t __sched __schedule_timeout_hr(ktime_t time, void *addr)
+{
+	struct hrtimer_sleeper t;
+	ktime_t remain;
+
+	hrtimer_init(&t.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	hrtimer_init_sleeper(&t, current);
+	__timer_stats_hrtimer_set_start_info(&t.timer, addr);
+	hrtimer_start(&t.timer, time, HRTIMER_MODE_REL);
+	schedule();
+	hrtimer_cancel(&t.timer);
+	remain = hrtimer_get_remaining(&t.timer);
+
+	if (ktime_to_ns(remain) < 0)
+		return ktime_set(0, 0);
+	else
+		return remain;
+}
+
+fastcall ktime_t __sched schedule_timeout_hr(ktime_t time)
+{
+	return __schedule_timeout_hr(time, __builtin_return_address(0));
+}
+EXPORT_SYMBOL_GPL(schedule_timeout_hr);
+
 static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
 {
 	hrtimer_init_sleeper(t, current);

--