Re: [REGRESSION][BISECTED] Long boot time with Xen HVM guests during PV spinlock initialization

[Teddy Astie]

Le 09/06/2026 à 17:17, Thomas Gleixner a écrit :
> On Tue, Jun 09 2026 at 11:27, Teddy Astie wrote:
> > Le 08/06/2026 à 17:15, Thomas Gleixner a écrit :
> > >    struct clocksource * __init __weak clocksource_default_clock(void)
> > >    {
> > > +	clocksource_register(&clocksource_jiffies);
> > >    	return &clocksource_jiffies;
> > >    }
> > >    
> >
> > Hmm, there's a case where clocksource_mutex gets taken twice (both in
> > __clocksource_register_scale() (through clocksource_register()) and
> > clocksource_done_booting()).
>
> Bah.
>
> > What about making clocksource_jiffies gain ->enable() to setup what ever
> > needs to be (like calling __clocksource_update_freq_scale()) ?
>
> Doesn't work either.
>
> Updated version below. It's not pretty, but it should cure your
> problem. If that's confirmed I think about a less ugly solution.
>
> Thanks,
>
>          tglx
> ---
> --- a/kernel/time/jiffies.c
> +++ b/kernel/time/jiffies.c
> @@ -60,15 +60,14 @@ EXPORT_SYMBOL(get_jiffies_64);
>   
>   EXPORT_SYMBOL(jiffies);
>   
> -static int __init init_jiffies_clocksource(void)
> -{
> -	return __clocksource_register(&clocksource_jiffies);
> -}
> -
> -core_initcall(init_jiffies_clocksource);
> +static bool cs_jiffies_registered __initdata;
>   
>   struct clocksource * __init __weak clocksource_default_clock(void)
>   {
> +	if (!cs_jiffies_registered) {
> +		__clocksource_register(&clocksource_jiffies);
> +		cs_jiffies_registered = true;
> +	}
>   	return &clocksource_jiffies;
>   }
>   

Yes, that fixes it.

Teddy

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