Re: [PATCH v3 2/2] accel/tcg: Register a force_rcu notifier

[Greg Kurz <groug@kaod.org>]

On Tue, 9 Nov 2021 19:03:56 +0100
Paolo Bonzini <pbonzini@redhat.com> wrote:

> On 11/9/21 18:24, Greg Kurz wrote:> Anyway, it seems more explicit to use rr_current_cpu.
> > 
> >> Alternately, no async_run_on_cpu at all, just rr_kick_next_cpu().
> >>
> > 
> > Heh, this looks even better ! I'll try this right away.
> 
> Once you've tested it I can queue the series with just a
> 
> --- a/accel/tcg/tcg-accel-ops-rr.c
> +++ b/accel/tcg/tcg-accel-ops-rr.c
> @@ -141,10 +141,10 @@ static void do_nothing(CPUState *cpu, run_on_cpu_data d)
>   static void rr_force_rcu(Notifier *notify, void *data)
>   {
>       /*
> -     * Called with rcu_registry_lock held, using async_run_on_cpu() ensures
> -     * that there are no deadlocks.
> +     * Called with rcu_registry_lock held.  rr_kick_next_cpu() is
> +     * asynchronous, so there cannot be deadlocks.
>        */
> -    async_run_on_cpu(first_cpu, do_nothing, RUN_ON_CPU_NULL);
> +    rr_kick_next_cpu();
>   }
>   
>   /*
> 
> squashed in.
> 

I've tested and it works just fine. I need to send a v4 anyway so that
the commit message is in sync with the code changes.

Cheers,

--
Greg

> Paolo
>