On Tue, 3 Sep 2013 21:51:52 -0400
Steven Rostedt <rost...@goodmis.org> wrote:
> > > void ftrace_unsafe_rcu_checker_disable(void)
> > > {
> > > atomic_inc(&ftrace_unsafe_rcu_disabled);
> > > + /* Make sure the update is seen immediately */
> > > + smp_wmb();
> >
> > smp_mb__after_atomic_inc()?
>
> Yep.
>
> >
> > > }
> > >
> > > void ftrace_unsafe_rcu_checker_enable(void)
> > > {
> > > atomic_dec(&ftrace_unsafe_rcu_disabled);
> > > + /* Make sure the update is seen immediately */
> > > + smp_wmb();
> >
> > smp_mb__after_atomic_dec()?
>
> Yep.
>
> >
> > > }
> > >
> > > static DEFINE_PER_CPU(unsigned long, ftrace_rcu_func);
> > > @@ -588,15 +593,14 @@ static void
> > > ftrace_unsafe_callback(unsigned long ip, unsigned long parent_ip,
> > > struct ftrace_ops *op, struct pt_regs *pt_regs)
> > > {
> > > - int bit;
> > > -
> > > + /* Make sure we see disabled or not first */
> > > + smp_rmb();
> >
> > smp_mb__before_atomic_inc()?
>
> Yep.
>
> I'll update it and restart my tests.
>
Although, this will punish archs that need the mb(), as IIUC, smp_mb()
is heavier weight than smp_wmb() or smp_rmb().
-- Steve
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