On Tue, Sep 03, 2013 at 10:01:15PM -0400, Steven Rostedt wrote:
> On Tue, 3 Sep 2013 18:24:04 -0700
> "Paul E. McKenney" <paul...@linux.vnet.ibm.com> wrote:
>
>
> > > 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()?
> >
>
> Ah, but this is before an atomic_read(), and not an atomic_inc(), thus
> the normal smp_rmb() is still required.
Good point, color me blind, dazed, and confused.
Thanx, Paul
> -- Steve
>
> > > if (atomic_read(&ftrace_unsafe_rcu_disabled))
> > > return;
> > >
> > > preempt_disable_notrace();
> > >
>
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