linux-kernel - Re: [PATCH v3 02/16] cacheinfo: Add helper to access any cache index for a given CPU

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Message-ID: <20220601124501.v4ylb4oqs4uq2oxj@bogus>
Date:   Wed, 1 Jun 2022 13:45:01 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Gavin Shan <gshan@...hat.com>
Cc:     linux-kernel@...r.kernel.org, Atish Patra <atishp@...shpatra.org>,
        Atish Patra <atishp@...osinc.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Qing Wang <wangqing@...o.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-riscv@...ts.infradead.org, Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH v3 02/16] cacheinfo: Add helper to access any cache index
 for a given CPU

On Wed, Jun 01, 2022 at 10:44:20AM +0800, Gavin Shan wrote:
> Hi Sudeep,
> 
> On 5/25/22 4:14 PM, Sudeep Holla wrote:
> > The cacheinfo for a given CPU at a given index is used at quite a few
> > places by fetching the base point for index 0 using the helper
> > per_cpu_cacheinfo(cpu) and offseting it by the required index.
> > 
> > Instead, add another helper to fetch the required pointer directly and
> > use it to simplify and improve readability.
> > 
> > Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> > ---
> >   drivers/base/cacheinfo.c | 14 +++++++-------
> >   1 file changed, 7 insertions(+), 7 deletions(-)
> > 
> 
> s/offseting/offsetting
> 
> It looks good to me with below nits fixed:
> 
> Reviewed-by: Gavin Shan <gshan@...hat.com>
> 
> 
> > diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
> > index b0bde272e2ae..c4547d8ac6f3 100644
> > --- a/drivers/base/cacheinfo.c
> > +++ b/drivers/base/cacheinfo.c
> > @@ -25,6 +25,8 @@ static DEFINE_PER_CPU(struct cpu_cacheinfo, ci_cpu_cacheinfo);
> >   #define ci_cacheinfo(cpu)	(&per_cpu(ci_cpu_cacheinfo, cpu))
> >   #define cache_leaves(cpu)	(ci_cacheinfo(cpu)->num_leaves)
> >   #define per_cpu_cacheinfo(cpu)	(ci_cacheinfo(cpu)->info_list)
> > +#define per_cpu_cacheinfo_idx(cpu, idx)		\
> > +				(per_cpu_cacheinfo(cpu) + (idx))
> >   struct cpu_cacheinfo *get_cpu_cacheinfo(unsigned int cpu)
> >   {
> > @@ -172,7 +174,7 @@ static int cache_setup_of_node(unsigned int cpu)
> >   	}
> >   	while (index < cache_leaves(cpu)) {
> > -		this_leaf = this_cpu_ci->info_list + index;
> > +		this_leaf = per_cpu_cacheinfo_idx(cpu, index);
> >   		if (this_leaf->level != 1)
> >   			np = of_find_next_cache_node(np);
> >   		else
> > @@ -231,7 +233,7 @@ static int cache_shared_cpu_map_setup(unsigned int cpu)
> >   	for (index = 0; index < cache_leaves(cpu); index++) {
> >   		unsigned int i;
> > -		this_leaf = this_cpu_ci->info_list + index;
> > +		this_leaf = per_cpu_cacheinfo_idx(cpu, index);
> >   		/* skip if shared_cpu_map is already populated */
> >   		if (!cpumask_empty(&this_leaf->shared_cpu_map))
> >   			continue;
> > @@ -242,7 +244,7 @@ static int cache_shared_cpu_map_setup(unsigned int cpu)
> >   			if (i == cpu || !sib_cpu_ci->info_list)
> >   				continue;/* skip if itself or no cacheinfo */
> > -			sib_leaf = sib_cpu_ci->info_list + index;
> > +			sib_leaf = per_cpu_cacheinfo_idx(i, index);
> >   			if (cache_leaves_are_shared(this_leaf, sib_leaf)) {
> >   				cpumask_set_cpu(cpu, &sib_leaf->shared_cpu_map);
> >   				cpumask_set_cpu(i, &this_leaf->shared_cpu_map);
> > @@ -258,12 +260,11 @@ static int cache_shared_cpu_map_setup(unsigned int cpu)
> >   static void cache_shared_cpu_map_remove(unsigned int cpu)
> >   {
> > -	struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(cpu);
> >   	struct cacheinfo *this_leaf, *sib_leaf;
> >   	unsigned int sibling, index;
> >   	for (index = 0; index < cache_leaves(cpu); index++) {
> > -		this_leaf = this_cpu_ci->info_list + index;
> > +		this_leaf = per_cpu_cacheinfo_idx(cpu, index);
> >   		for_each_cpu(sibling, &this_leaf->shared_cpu_map) {
> >   			struct cpu_cacheinfo *sib_cpu_ci;
> > 
> 
> In cache_shared_cpu_map_remove(), the newly introduced macro
> can be applied when the sibling CPU's cache info is fetched.
> 
>     sib_leaf = sib_cpu_ci->info_list + index;
> 
>     to
> 
>     sib_leaf = per_cpu_cacheinfo_idx(sibling, index);
> 

Right, I clearly missed to identify this. Thanks again for the review, all
other comments are now fixed locally and pushed @[1], will post them as part
of next version.

--
Regards,
Sudeep

[1] https://git.kernel.org/sudeep.holla/h/arch_topology