netdev - Re: [RFC PATCH 4/4] treewide: Use clocksource id for struct system_counterval

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Date: Fri, 15 Sep 2023 15:30:23 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Peter Hilber <peter.hilber@...nsynergy.com>,
 linux-kernel@...r.kernel.org, kvm@...r.kernel.org, kvmarm@...ts.linux.dev
Cc: Peter Hilber <peter.hilber@...nsynergy.com>, Ingo Molnar
 <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen
 <dave.hansen@...ux.intel.com>, x86@...nel.org, "H. Peter Anvin"
 <hpa@...or.com>, Richard Cochran <richardcochran@...il.com>, John Stultz
 <jstultz@...gle.com>, Stephen Boyd <sboyd@...nel.org>,
 netdev@...r.kernel.org, Marc Zyngier <maz@...nel.org>, Paolo Bonzini
 <pbonzini@...hat.com>, Oliver Upton <oliver.upton@...ux.dev>, James Morse
 <james.morse@....com>, Suzuki K Poulose <suzuki.poulose@....com>, Zenghui
 Yu <yuzenghui@...wei.com>, Sean Christopherson <seanjc@...gle.com>
Subject: Re: [RFC PATCH 4/4] treewide: Use clocksource id for struct
 system_counterval_t

Peter!

On Fri, Aug 18 2023 at 03:12, Peter Hilber wrote:
> --- a/arch/x86/kernel/tsc.c
> +++ b/arch/x86/kernel/tsc.c
> @@ -1313,7 +1313,7 @@ struct system_counterval_t convert_art_to_tsc(u64 art)
>  	res += tmp + art_to_tsc_offset;
>  
>  	return (struct system_counterval_t) {
> -		.cs = have_art ? &clocksource_tsc : NULL,
> +		.cs_id = have_art ? CSID_TSC : CSID_GENERIC,
>  		.cycles = res

Can you please change all of this so that:

    patch 1:   Adds cs_id to struct system_counterval_t
    patch 2-4: Add the clocksource ID and set the cs_id field
    patch 5:   Switches the core to evaluate cs_id
    patch 6:   Remove the cs field from system_counterval_t

> --- a/include/linux/timekeeping.h
> +++ b/include/linux/timekeeping.h
> @@ -270,12 +270,12 @@ struct system_device_crosststamp {
>   * struct system_counterval_t - system counter value with the pointer to the
>   *				corresponding clocksource
>   * @cycles:	System counter value
> - * @cs:		Clocksource corresponding to system counter value. Used by
> + * @cs_id:	Clocksource corresponding to system counter value. Used by
>   *		timekeeping code to verify comparibility of two cycle values

That comment is inaccurate. It's not longer the clocksource itself. It's
the ID which is used for validation.

Thanks,

        tglx