On Sun, Jan 15, 2023 at 4:25 PM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> On Thu, 12 Jan 2023 00:52:22 +0000
> "Joel Fernandes (Google)" <joel@xxxxxxxxxxxxxxxxx> wrote:
>
> > -- a/kernel/rcu/update.c
> > +++ b/kernel/rcu/update.c
> > @@ -144,8 +144,45 @@ bool rcu_gp_is_normal(void)
> > }
> > EXPORT_SYMBOL_GPL(rcu_gp_is_normal);
> >
> > -static atomic_t rcu_expedited_nesting = ATOMIC_INIT(1);
> > +static atomic_t rcu_async_hurry_nesting = ATOMIC_INIT(1);
> > +/*
> > + * Should call_rcu() callbacks be processed with urgency or are
> > + * they OK being executed with arbitrary delays?
> > + */
> > +bool rcu_async_should_hurry(void)
> > +{
> > + return !IS_ENABLED(CONFIG_RCU_LAZY) ||
> > + atomic_read(&rcu_async_hurry_nesting);
> > +}
> > +EXPORT_SYMBOL_GPL(rcu_async_should_hurry);
> > +
> > +/**
> > + * rcu_async_hurry - Make future async RCU callbacks not lazy.
> > + *
> > + * After a call to this function, future calls to call_rcu()
> > + * will be processed in a timely fashion.
> > + */
> > +void rcu_async_hurry(void)
> > +{
> > + if (IS_ENABLED(CONFIG_RCU_LAZY))
> > + atomic_inc(&rcu_async_hurry_nesting);
> > +}
> > +EXPORT_SYMBOL_GPL(rcu_async_hurry);
> >
>
> Where do you plan on calling these externally, as they are being
> marked exported?
>
> If you allow random drivers to enable this, I can see something
> enabling it and hitting an error path that causes it to never disable
> it.
You mean, just like rcu_expedite_gp() ?
> I wouldn't have EXPORT_SYMBOL_GPL() unless you really know that it is
> needed externally.
At the moment it is not called externally but in the future, it could
be from rcutorture. If you see rcu_expedite_gp(), that is exported
too. I was just modeling it around that API.
thanks,
- Joel
>
> -- Steve
>
>
> > +/**
> > + * rcu_async_relax - Make future async RCU callbacks lazy.
> > + *
> > + * After a call to this function, future calls to call_rcu()
> > + * will be processed in a lazy fashion.
> > + */
> > +void rcu_async_relax(void)
> > +{
> > + if (IS_ENABLED(CONFIG_RCU_LAZY))
> > + atomic_dec(&rcu_async_hurry_nesting);
> > +}
> > +EXPORT_SYMBOL_GPL(rcu_async_relax);
> > +
> > +static atomic_t rcu_expedited_nesting = ATOMIC_INIT(1);
