Re: [PATCH v3 08/22] rcu,tracing: Create trace_rcu_{enter,exit}()

Peter Zijlstra
2020-02-19T15:58:51Z

On Wed, Feb 19, 2020 at 10:49:03AM -0500, Steven Rostedt wrote:
> On Wed, 19 Feb 2020 15:47:32 +0100
> Peter Zijlstra <peterz@infradead.org> wrote:

> > These helpers are macros because of header-hell; they're placed here
> > because of the proximity to nmi_{enter,exit{().

^^^^

> > +#define trace_rcu_enter() \
> > +({ \
> > + unsigned long state = 0; \
> > + if (!rcu_is_watching()) { \
> > + rcu_irq_enter_irqsave(); \
> > + state = 1; \
> > + } \
> > + state; \
> > +})
> > +
> > +#define trace_rcu_exit(state) \
> > +do { \
> > + if (state) \
> > + rcu_irq_exit_irqsave(); \
> > +} while (0)
> > +
>
> Is there a reason that these can't be static __always_inline functions?

It can be done, but then we need fwd declarations of those RCU functions
somewhere outside of rcupdate.h. It's all a bit of a mess.