Re: [PATCH v3 tip/core/rcu 1/9] rcu: Add call_rcu_tasks()

From: Paul E. McKenney
Date: Mon Aug 04 2014 - 09:51:19 EST


On Mon, Aug 04, 2014 at 03:25:25PM +0200, Oleg Nesterov wrote:
> On 08/03, Paul E. McKenney wrote:
> >
> > On Mon, Aug 04, 2014 at 08:37:37AM +0800, Lai Jiangshan wrote:
> > > An alternative solution:
> > > srcu_read_lock() before exit_notify(), srcu_read_unlock() after the last preempt_disable()
> > > in the do_exit, and synchronize_srcu() in rcu_tasks_kthread().
> >
> > That is a good way to synchronize with the exiting tasks, and I will
> > probably that that approach.
> >
> > I -thought- that Oleg was concerned about safely building the list to
> > start with, though.
>
> But for_each_process_thread() under rcu_read_lock() should work except
> it can miss the exiting tasks.
>
> So it seems that the clever Lai's trick should solve the problem.

Cool! Lai's trick seems to be doing well in early testing, so keeping
fingers firmly crossed. ;-)

Thanx, Paul

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