Re: [patch V6 12/37] x86/entry: Provide idtentry_entry/exit_cond_rcu()

[Paul E. McKenney]

On Thu, May 21, 2020 at 10:31:11AM +0200, Thomas Gleixner wrote:
> "Paul E. McKenney" <paulmck@xxxxxxxxxx> writes:
> > On Wed, May 20, 2020 at 03:15:31PM -0700, Paul E. McKenney wrote:
> > Same patch, but with updated commit log based on IRC discussion
> > with Andy.
> 
> Fun. I came up with the same thing before going to bed. Just that I
> named the function differently: rcu_irq_enter_check_tick()

I am good with that name.

> >  #if defined(CONFIG_TINY_RCU)
> >  
> > +static inline void tickle_nohz_for_rcu(void)
> > +{
> > +}
> > +
> >  static inline void rcu_nmi_enter(void)
> >  {
> >  }
> > @@ -23,6 +27,7 @@ static inline void rcu_nmi_exit(void)
> >  }
> >  
> >  #else
> > +extern void tickle_nohz_for_rcu(void);
> 
> And I made this a NOP for for !NOHZ_FULL systems and avoided the call if
> context tracking is not enabled at boot.
> 
> void __rcu_irq_enter_check_tick(void);
> 
> static inline void rcu_irq_enter_check_tick(void)
> {
> 	if (context_tracking_enabled())
>         	__rcu_irq_enter_check_tick();
> }

That certainly is a better approach!

So let's go with your version.  But could you please post it, just in
case reviewing an alternative version causes me to spot something?

							Thanx, Paul