linux-kernel - Re: [PATCH v3 17/38] x86/resctrl: Stop using the for_each_*_rdt

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Message-ID: <2b163af7-12d5-443d-a302-22d98c1facf1@intel.com>
Date: Fri, 28 Jun 2024 09:48:38 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: James Morse <james.morse@....com>, <x86@...nel.org>,
	<linux-kernel@...r.kernel.org>
CC: Fenghua Yu <fenghua.yu@...el.com>, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, H Peter Anvin
	<hpa@...or.com>, Babu Moger <Babu.Moger@....com>,
	<shameerali.kolothum.thodi@...wei.com>, D Scott Phillips OS
	<scott@...amperecomputing.com>, <carl@...amperecomputing.com>,
	<lcherian@...vell.com>, <bobo.shaobowang@...wei.com>,
	<tan.shaopeng@...itsu.com>, <baolin.wang@...ux.alibaba.com>, Jamie Iles
	<quic_jiles@...cinc.com>, Xin Hao <xhao@...ux.alibaba.com>,
	<peternewman@...gle.com>, <dfustini@...libre.com>, <amitsinght@...vell.com>,
	David Hildenbrand <david@...hat.com>, Rex Nie <rex.nie@...uarmicro.com>,
	"Dave Martin" <dave.martin@....com>, Shaopeng Tan
	<tan.shaopeng@...fujitsu.com>
Subject: Re: [PATCH v3 17/38] x86/resctrl: Stop using the
 for_each_*_rdt_resource() walkers

Hi James,

On 6/14/24 8:00 AM, James Morse wrote:
> The for_each_*_rdt_resource() helpers walk the architecture's array
> of structures, using the resctrl visible part as an iterator. These
> became over-complex when the structures were split into a
> filesystem and architecture-specific struct. This approach avoided
> the need to touch every call site.
> 
> Once the filesystem parts of resctrl are moved to /fs/, both the
> architecture's resource array, and the definition of those structures
> is no longer accessible. To support resctrl, each architecture would
> have to provide equally complex macros.
> 
> Change the resctrl code that uses these to walk through the resource_level
> enum and check the mon/alloc capable flags instead. Instances in core.c,
> and resctrl_arch_reset_resources() remain part of x86's architecture
> specific code.
> 
> Co-developed-by: Dave Martin <Dave.Martin@....com>
> Signed-off-by: Dave Martin <Dave.Martin@....com>
> Signed-off-by: James Morse <james.morse@....com>
> Tested-by: Peter Newman <peternewman@...gle.com>
> Tested-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
> ---
> Changes since v1:
>   * [Whitespace only] Fix bogus whitespace introduced in
>     rdtgroup_create_info_dir().
> 
>   * [Commit message only] Typo fix:
>     s/architectures/architecture's/g
> ---
>   arch/x86/kernel/cpu/resctrl/pseudo_lock.c |  7 +++++-
>   arch/x86/kernel/cpu/resctrl/rdtgroup.c    | 28 +++++++++++++++++++----
>   2 files changed, 30 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
> index aacf236dfe3b..ad20822bb64e 100644
> --- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
> +++ b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c
> @@ -840,6 +840,7 @@ bool rdtgroup_cbm_overlaps_pseudo_locked(struct rdt_domain *d, unsigned long cbm
>   bool rdtgroup_pseudo_locked_in_hierarchy(struct rdt_domain *d)
>   {
>   	cpumask_var_t cpu_with_psl;
> +	enum resctrl_res_level i;
>   	struct rdt_resource *r;
>   	struct rdt_domain *d_i;
>   	bool ret = false;
> @@ -854,7 +855,11 @@ bool rdtgroup_pseudo_locked_in_hierarchy(struct rdt_domain *d)
>   	 * First determine which cpus have pseudo-locked regions
>   	 * associated with them.
>   	 */
> -	for_each_alloc_capable_rdt_resource(r) {
> +	for (i = 0; i < RDT_NUM_RESOURCES; i++) {
> +		r = resctrl_arch_get_resource(i);
> +		if (!r->alloc_capable)
> +			continue;
> +

This looks like enough duplicate boilerplate for a new macro. For simplicity the
macro could require two arguments with enum resctrl_res_level also provided?

Reinette