Re: [PATCH] timer: Fix mod_timer_pinned() header commen (was: [PATCH RFC tip/core/rcu 4/4] rcu: Ensure that RCU_FAST_NO_HZ timers expire on correct CPU)

Steven Rostedt
2012-04-26T18:10:27Z

> ------------------------------------------------------------------------
>
> timer: Fix mod_timer_pinned() header comment
>
> The mod_timer_pinned() header comment states that it prevents timers
> from being migrated to a different CPU. This is not the case, instead,
> it ensures that the timer is posted to the current CPU, but does nothing
> to prevent CPU-hotplug operations from migrating the timer.
>
> This commit therefore brings the comment header into alignment with
> reality.
>
> Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

I'm seeing double :-)

>
> diff --git a/kernel/timer.c b/kernel/timer.c
> index a297ffc..7114336 100644
> --- a/kernel/timer.c
> +++ b/kernel/timer.c
> @@ -861,7 +861,12 @@ EXPORT_SYMBOL(mod_timer);
> *
> * mod_timer_pinned() is a way to update the expire field of an
> * active timer (if the timer is inactive it will be activated)
> - * and not allow the timer to be migrated to a different CPU.
> + * and to ensure that the timer is scheduled on the current CPU.

Add space here.

+ *

> + * Note that this does not prevent the timer from being migrated
> + * when the current CPU goes offline. If this is a problem for
> + * you, use CPU-hotplug notifiers to handle it correctly, for
> + * example, cancelling the timer when the corresponding CPU goes
> + * offline.
> *
> * mod_timer_pinned(timer, expires) is equivalent to:
> *

Adding a space will make the "Note" stand out more, and more likely seen
by people who use this function.

Other than that:

Acked-by: Steven Rostedt <rostedt@goodmis.org>

-- Steve