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Subject[patch 18/21] Create hrtimer nanosleep API

- introduce the hrtimer_nanosleep() and hrtimer_nanosleep_real() APIs.
Not yet used by any code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/hrtimer.h | 6 ++
kernel/hrtimer.c | 127 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 133 insertions(+)
Index: linux-2.6.15-rc5/include/linux/hrtimer.h
===================================================================
--- linux-2.6.15-rc5.orig/include/linux/hrtimer.h
+++ linux-2.6.15-rc5/include/linux/hrtimer.h
@@ -121,6 +121,12 @@ static inline int hrtimer_active(const s
extern unsigned long hrtimer_forward(struct hrtimer *timer,
const ktime_t interval);

+/* Precise sleep: */
+extern long hrtimer_nanosleep(struct timespec *rqtp,
+ struct timespec __user *rmtp,
+ const enum hrtimer_mode mode,
+ const clockid_t clockid);
+
/* Soft interrupt function to run the hrtimer queues: */
extern void hrtimer_run_queues(void);

Index: linux-2.6.15-rc5/kernel/hrtimer.c
===================================================================
--- linux-2.6.15-rc5.orig/kernel/hrtimer.c
+++ linux-2.6.15-rc5/kernel/hrtimer.c
@@ -581,6 +581,133 @@ void hrtimer_run_queues(void)
}

/*
+ * Sleep related functions:
+ */
+
+/**
+ * schedule_hrtimer - sleep until timeout
+ *
+ * @timer: hrtimer variable initialized with the correct clock base
+ * @mode: timeout value is abs/rel
+ *
+ * Make the current task sleep until @timeout is
+ * elapsed.
+ *
+ * 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
+ * will be returned
+ *
+ * The current task state is guaranteed to be TASK_RUNNING when this
+ * routine returns.
+ */
+static ktime_t __sched
+schedule_hrtimer(struct hrtimer *timer, const enum hrtimer_mode mode)
+{
+ /* fn stays NULL, meaning single-shot wakeup: */
+ timer->data = current;
+
+ hrtimer_start(timer, timer->expires, mode);
+
+ schedule();
+ hrtimer_cancel(timer);
+
+ /* Return the remaining time: */
+ if (timer->state != HRTIMER_EXPIRED)
+ return ktime_sub(timer->expires, timer->base->get_time());
+ else
+ return (ktime_t) {.tv64 = 0 };
+}
+
+static inline ktime_t __sched
+schedule_hrtimer_interruptible(struct hrtimer *timer,
+ const enum hrtimer_mode mode)
+{
+ set_current_state(TASK_INTERRUPTIBLE);
+
+ return schedule_hrtimer(timer, mode);
+}
+
+static long __sched
+nanosleep_restart(struct restart_block *restart, clockid_t clockid)
+{
+ struct timespec __user *rmtp, tu;
+ void *rfn_save = restart->fn;
+ struct hrtimer timer;
+ ktime_t rem;
+
+ restart->fn = do_no_restart_syscall;
+
+ hrtimer_init(&timer, clockid);
+
+ timer.expires.tv64 = ((u64)restart->arg1 << 32) | (u64) restart->arg0;
+
+ rem = schedule_hrtimer_interruptible(&timer, HRTIMER_ABS);
+
+ if (rem.tv64 <= 0)
+ return 0;
+
+ rmtp = (struct timespec __user *) restart->arg2;
+ tu = ktime_to_timespec(rem);
+ if (rmtp && copy_to_user(rmtp, &tu, sizeof(tu)))
+ return -EFAULT;
+
+ restart->fn = rfn_save;
+
+ /* The other values in restart are already filled in */
+ return -ERESTART_RESTARTBLOCK;
+}
+
+static long __sched nanosleep_restart_mono(struct restart_block *restart)
+{
+ return nanosleep_restart(restart, CLOCK_MONOTONIC);
+}
+
+static long __sched nanosleep_restart_real(struct restart_block *restart)
+{
+ return nanosleep_restart(restart, CLOCK_REALTIME);
+}
+
+long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
+ const enum hrtimer_mode mode, const clockid_t clockid)
+{
+ struct restart_block *restart;
+ struct hrtimer timer;
+ struct timespec tu;
+ ktime_t rem;
+
+ hrtimer_init(&timer, clockid);
+
+ timer.expires = timespec_to_ktime(*rqtp);
+
+ rem = schedule_hrtimer_interruptible(&timer, mode);
+ if (rem.tv64 <= 0)
+ return 0;
+
+ /* Absolute timers do not update the rmtp value: */
+ if (mode == HRTIMER_ABS)
+ return -ERESTARTNOHAND;
+
+ tu = ktime_to_timespec(rem);
+
+ if (rmtp && copy_to_user(rmtp, &tu, sizeof(tu)))
+ return -EFAULT;
+
+ restart = &current_thread_info()->restart_block;
+ restart->fn = (clockid == CLOCK_MONOTONIC) ?
+ nanosleep_restart_mono : nanosleep_restart_real;
+ restart->arg0 = timer.expires.tv64 & 0xFFFFFFFF;
+ restart->arg1 = timer.expires.tv64 >> 32;
+ restart->arg2 = (unsigned long) rmtp;
+
+ return -ERESTART_RESTARTBLOCK;
+}
+
+/*
* Functions related to boot-time initialization:
*/
static void __devinit init_hrtimers_cpu(int cpu)
--

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