On 02/11, Srivatsa S. Bhat wrote:
>
> +static DECLARE_RWSEM(cpu_hotplug_rwsem);
> +
> +void cpu_notifier_register_begin(void)
> +{
> + down_read(&cpu_hotplug_rwsem);
> +}
> +
> +void cpu_notifier_register_end(void)
> +{
> + up_read(&cpu_hotplug_rwsem);
> +}
> +
> /* Serializes the updates to cpu_online_mask, cpu_present_mask */
> static DEFINE_MUTEX(cpu_add_remove_lock);
>
> @@ -32,12 +45,14 @@ static DEFINE_MUTEX(cpu_add_remove_lock);
> */
> void cpu_maps_update_begin(void)
> {
> + down_write(&cpu_hotplug_rwsem);
> mutex_lock(&cpu_add_remove_lock);
> }
>
> void cpu_maps_update_done(void)
> {
> mutex_unlock(&cpu_add_remove_lock);
> + up_write(&cpu_hotplug_rwsem);
> }
I am a bit confused... If we do this, why we can't simply turn
cpu_add_remove_lock into rw_semaphore?
Oleg.
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