Re: [PATCH 6/9] rv: Ensure synchronous cleanup for HA monitors

[Gabriele Monaco]

On Mon, 2026-05-18 at 13:54 +0200, Gabriele Monaco wrote:
> Something like:
> 
> void __ha_monitor_timer_callback() {
>       guard(rcu)(); //this is only for waiters, let them wait more
> 
>       if (unlikely(!da_monitor_handling_event(&ha_mon->da_mon)))
>               return;
>       smp_rmb();
>       curr_state = READ_ONCE(ha_mon->da_mon.curr_state);
>       ...
> }
> 
> void da_monitor_reset() {
>       da_monitor_reset_hook(da_mon);
>       WRITE_ONCE(da_mon->monitoring, 0);
>       smp_wmb();
>       WRITE_ONCE(da_mon->curr_state, model_get_initial_state());
> }

That's obviously not going to work unless I read curr_state earlier (and use the
acquire/release helpers while at it):

void __ha_monitor_timer_callback() {
        guard(rcu)(); //this is only for waiters, let them wait more

        curr_state = smp_load_acquire(&ha_mon->da_mon.curr_state);
        if (unlikely(!da_monitor_handling_event(&ha_mon->da_mon)))
                return;
        ...
}

void da_monitor_reset() {
        da_monitor_reset_hook(da_mon);
        WRITE_ONCE(da_mon->monitoring, 0);
        smp_store_release(&da_mon->curr_state, model_get_initial_state());
}