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 expireon correct CPU)

[Steven Rostedt]

> ------------------------------------------------------------------------
> 
> 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@xxxxxxxxxx>
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>

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@xxxxxxxxxxx>

-- Steve


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