[patch 3/5] hrtimer: Document hrtimer_forward[_now]() proper

[Thomas Gleixner <tglx@linutronix.de>]

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Document the calling context conditions.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 include/linux/hrtimer.h |   17 ++++++++++++++++-
 kernel/time/hrtimer.c   |    8 ++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

Index: linux/include/linux/hrtimer.h
===================================================================
--- linux.orig/include/linux/hrtimer.h
+++ linux/include/linux/hrtimer.h
@@ -418,7 +418,22 @@ static inline int hrtimer_callback_runni
 extern u64
 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 
-/* Forward a hrtimer so it expires after the hrtimer's current now */
+/**
+ * hrtimer_forward_now - forward the timer expiry so it expires after now
+ * @timer:	hrtimer to forward
+ * @interval:	the interval to forward
+ *
+ * Forward the timer expiry so it will expire after the current time
+ * of the hrtimer clock base. Returns the number of overruns.
+ *
+ * Can be safely called from the callback function of @timer. If
+ * called from other contexts @timer must neither be enqueued nor
+ * running the callback and the caller needs to take care of
+ * serialization.
+ *
+ * Note: This only updates the timer expiry value and does not requeue
+ * the timer.
+ */
 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
 				      ktime_t interval)
 {
Index: linux/kernel/time/hrtimer.c
===================================================================
--- linux.orig/kernel/time/hrtimer.c
+++ linux/kernel/time/hrtimer.c
@@ -801,6 +801,14 @@ void unlock_hrtimer_base(const struct hr
  *
  * Forward the timer expiry so it will expire in the future.
  * Returns the number of overruns.
+ *
+ * Can be safely called from the callback function of @timer. If
+ * called from other contexts @timer must neither be enqueued nor
+ * running the callback and the caller needs to take care of
+ * serialization.
+ *
+ * Note: This only updates the timer expiry value and does not requeue
+ * the timer.
  */
 u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
 {