Re: [PATCH v2 39/45] arm_mpam: resctrl: Call resctrl_init() on platforms that can support resctrl

Ben Horgan
2026-01-08T14:53:47Z

Hi Jonathan,

On 1/6/26 14:58, Jonathan Cameron wrote:
> On Fri, 19 Dec 2025 18:11:41 +0000
> Ben Horgan <ben.horgan@arm.com> wrote:
>
>> From: James Morse <james.morse@arm.com>
>>
>> Now that MPAM links against resctrl, call resctrl_init() to register the
>> filesystem and setup resctrl's structures.
>>
>> Signed-off-by: James Morse <james.morse@arm.com>
>> Signed-off-by: Ben Horgan <ben.horgan@arm.com>
>
> Just minor suggestions inline. I'm not sure the for loop macros
> are worth doing but that particular pair of loops feel awfully familiar
> at this point, so maybe.
>
> Either way..
>
> Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
>
>> diff --git a/drivers/resctrl/mpam_resctrl.c b/drivers/resctrl/mpam_resctrl.c
>> index 059148c38a38..bbb12b5dfd8c 100644
>> --- a/drivers/resctrl/mpam_resctrl.c
>> +++ b/drivers/resctrl/mpam_resctrl.c
>
>> @@ -1840,11 +1861,70 @@ int mpam_resctrl_setup(void)
>> pr_warn("Number of PMG is not a power of 2! resctrl may misbehave");
>> }
>>
>> - /* TODO: call resctrl_init() */
>> + err = resctrl_init();
>> + if (!err)
>> + WRITE_ONCE(resctrl_enabled, true);
>
> Trivial but I'd prefer the error path out of line.
>
> if (err)
> return err;
>
> WRITE_ONCE(resctrl_enabled, true);
>
> return 0;

Ok, updated.

>>
>> return err;
>> }
>
>> +
>> +/*
>> + * The driver is detaching an MSC from this class, if resctrl was using it,
>> + * pull on resctrl_exit().
>> + */
>> +void mpam_resctrl_teardown_class(struct mpam_class *class)
>> +{
>> + int i;
>> + struct mpam_resctrl_res *res;
>> + struct mpam_resctrl_mon *mon;
>> +
>> + might_sleep();
>> +
>> + for (i = 0; i < RDT_NUM_RESOURCES; i++) {
> There are enough iterators over these that I wonder
> if it is worth some macros.
>
> for_each_mpam_resctrl_control(res) {
> }
> and
> for_each_mpam_resctrl_counter(mon) {
> }

The index is often needed too so I changed to helpers that include it too:
for_each_mpam_resctrl_control(res, rid) and
for_each_mpam_resctrl_mon(mon, eventid).

>
>
>> + res = &mpam_resctrl_controls[i];
>> + if (res->class == class) {
>> + res->class = NULL;
>> + break;
>> + }
>> + }
>> + for (i = 0; i < QOS_NUM_EVENTS; i++) {
>> + mon = &mpam_resctrl_counters[i];
>> + if (mon->class == class) {
>> + mon->class = NULL;
>> +
>> + mpam_resctrl_teardown_mon(mon, class);
>> +
>> + break;
>> + }
>> + }
>> +}
>> +
>> static int __init __cacheinfo_ready(void)
>> {
>> cacheinfo_ready = true;
>

Thanks,

Ben