On Sat, Jan 14, 2017 at 12:54:42AM -0800, Paul E. McKenney wrote:
> /*
> + * Record entry into an extended quiescent state. This is only to be
> + * called when not already in an extended quiescent state.
> + */
> +static void rcu_dynticks_eqs_enter(void)
> +{
> + struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
> +
> + /*
> + * CPUs seeing atomic_inc() must see prior RCU read-side critical
> + * sections, and we also must force ordering with the next idle
> + * sojourn.
> + */
> + smp_mb__before_atomic(); /* See above. */
> + atomic_inc(&rdtp->dynticks);
> + smp_mb__after_atomic(); /* See above. */
> + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
> + atomic_read(&rdtp->dynticks) & 0x1);
> +}
In an earlier patch you replaced things with atomic_add_return(), why
not use atomic_inc_return() here?
