linux-kernel - Re: [PATCH v7 15/31] x86,fs/resctrl: Add an architectural hook called for each mount

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Message-ID: <66018504-0acf-4c8a-a467-c89c9088be61@intel.com>
Date: Fri, 25 Jul 2025 16:35:36 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghuay@...dia.com>, "Maciej
 Wieczor-Retman" <maciej.wieczor-retman@...el.com>, Peter Newman
	<peternewman@...gle.com>, James Morse <james.morse@....com>, Babu Moger
	<babu.moger@....com>, Drew Fustini <dfustini@...libre.com>, Dave Martin
	<Dave.Martin@....com>, Chen Yu <yu.c.chen@...el.com>
CC: <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v7 15/31] x86,fs/resctrl: Add an architectural hook called
 for each mount

Hi Tony,

On 7/11/25 4:53 PM, Tony Luck wrote:
> Enumeration of Intel telemetry events is not complete when the
> resctrl "late_init" code is executed.

Could you please expand the context to provide detail on why
this enumeration is not complete at resctrl init time? What guarantee
is there that the enumeration will be complete at resctrl mount time?

> 
> Add a hook at the beginning of the mount code that will be used
> to check for telemetry events and initialize if any are found.
> 
> The hook is called on every attempted mount. But expectations are that

"Call the hook ..." (I do not think I need to point these out anymore,
will leave to you to rework all changelogs)

> most actions (like enumeration) will only need to be performed
> on the first call.
> 
> The call is made with no locks held. Architecture code is responsible
> for any required locking.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
>  include/linux/resctrl.h            | 6 ++++++
>  arch/x86/kernel/cpu/resctrl/core.c | 9 +++++++++
>  fs/resctrl/rdtgroup.c              | 2 ++
>  3 files changed, 17 insertions(+)
> 
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index e9a1cabfc724..d2fc0fcd0226 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -460,6 +460,12 @@ void resctrl_offline_mon_domain(struct rdt_resource *r, struct rdt_domain_hdr *h
>  void resctrl_online_cpu(unsigned int cpu);
>  void resctrl_offline_cpu(unsigned int cpu);
>  
> +/*
> + * Architecture hook called for each attempted file system mount.

"for each attempted file system mount" -> "at beginning of each file system mount attempt"?

Reinette