Re: [PATCH v3 2/2] timers: Fix documentation for schedule_timeout() and similar

Thomas Gleixner
2016-10-20T21:06:48Z

On Thu, 20 Oct 2016, Douglas Anderson wrote:
> +++ b/kernel/time/hrtimer.c
> @@ -1742,15 +1742,19 @@ schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
> * You can set the task state as follows -
> *
> * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
> - * pass before the routine returns.
> + * pass before the routine returns unless the current task is explicitly
> + * woken up, (e.g. by wake_up_process())".

The double quote is stray.

> *
> * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
> - * delivered to the current task.
> + * delivered to the current task or the current task is explicitly woken
> + * up.
> *
> * The current task state is guaranteed to be TASK_RUNNING when this
> * routine returns.
> *
> - * Returns 0 when the timer has expired otherwise -EINTR
> + * Returns 0 when the timer has expired otherwise -EINTR. Note that
> + * -EINTR can still be returned even if the task state is
> + * TASK_UNINTERRUPTIBLE if the current task is explicitly woken up.

I'd prefer to word it this way:

Returns 0 when the timer has expired. If the task was woken before the
timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or by
an explicit wakeup, it returns -EINTR.

> */
> int __sched schedule_hrtimeout_range(ktime_t *expires, u64 delta,
> const enum hrtimer_mode mode)
> @@ -1772,15 +1776,19 @@ EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
> * You can set the task state as follows -
> *
> * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
> - * pass before the routine returns.
> + * pass before the routine returns unless the current task is explicitly
> + * woken up, (e.g. by wake_up_process())".

See above

> *
> * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
> - * delivered to the current task.
> + * delivered to the current task or the current task is explicitly woken
> + * up.
> *
> * The current task state is guaranteed to be TASK_RUNNING when this
> * routine returns.
> *
> - * Returns 0 when the timer has expired otherwise -EINTR
> + * Returns 0 when the timer has expired otherwise -EINTR. Note that
> + * -EINTR can still be returned even if the task state is
> + * TASK_UNINTERRUPTIBLE if the current task is explicitly woken up.

See above

> @@ -1691,11 +1691,12 @@ static void process_timeout(unsigned long __data)
> * You can set the task state as follows -
> *
> * %TASK_UNINTERRUPTIBLE - at least @timeout jiffies are guaranteed to
> - * pass before the routine returns. The routine will return 0
> + * pass before the routine returns unless the current task is explicitly
> + * woken up, (e.g. by wake_up_process())".
> *
> * %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
> + * delivered to the current task or the current task is explicitly woken
> + * up.
> *
> * The current task state is guaranteed to be TASK_RUNNING when this
> * routine returns.
> @@ -1704,7 +1705,9 @@ static void process_timeout(unsigned long __data)
> * the CPU away without a bound on the timeout. In this case the return
> * value will be %MAX_SCHEDULE_TIMEOUT.
> *
> - * In all cases the return value is guaranteed to be non-negative.
> + * Returns 0 when the timer has expired otherwise the remaining time in
> + * jiffies will be returned. In all cases the return value is guaranteed
> + * to be non-negative.

That one is fine.

Thanks,

tglx