Re: linux-next 20111025: warnings in rcu_idle_exit_common()/rcu_idle_enter_common()

Paul E. McKenney
2011-11-02T15:19:20Z

On Wed, Nov 02, 2011 at 10:56:26AM -0400, Steven Rostedt wrote:
> On Wed, 2011-11-02 at 07:44 -0700, Paul E. McKenney wrote:
>
> > rcu: Fix idle-task checks
> >
> > RCU has traditionally relied on idle_cpu() to determine whether a given
> > CPU is running in the context of an idle task, but recent changes have
> > invalidated this approach.
>
> Correct. idle_cpu() returns if the CPU is idle or not, not if the CPU is
> running the idle thread. If the CPU wakes up on the idle thread and
> there's tasks on the run queue, then idle_cpu() will return false, even
> though the task running is the idle thread. But the CPU itself is not
> technically idle.
>
> Acked-by: Steven Rostedt <rostedt@goodmis.org>

Thank you, Steven! I have added your Acked-by.

Thanx, Paul