Re: [patch] Real-Time Preemption, -RT-2.6.12-rc1-V0.7.41-07

Paul E. McKenney <[email protected]> wrote:
>
> +void rcu_read_unlock(void)
> +{
> +       int cpu;
> +
> +       if (--current->rcu_read_lock_nesting == 0) {
> +               atomic_dec(&current->rcu_data->active_readers);
> +               /*
> +                * Check whether we have reached quiescent state.
> +                * Note! This is only for the local CPU, not for
> +                * current->rcu_data's CPU [which typically is the
> +                * current CPU, but may also be another CPU].
> +                */
> +               cpu = get_cpu();
> 
> And need an smp_mb() here, again for non-x86 CPUs.

The atomic_dec is already a barrier.

Cheers,
-- 
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