Re: [PATCH v1 04/31] x86/resctrl: Add helper for setting CPU default properties

Reinette Chatre
2024-04-15T17:45:14Z

Hi Dave,

On 4/12/2024 9:13 AM, Dave Martin wrote:
> On Mon, Apr 08, 2024 at 08:15:03PM -0700, Reinette Chatre wrote:
>> Hi James,
>>
>> On 3/21/2024 9:50 AM, James Morse wrote:
>>
>>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>>> @@ -3623,14 +3623,18 @@ static int rdtgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
>>> static int rdtgroup_rmdir_mon(struct rdtgroup *rdtgrp, cpumask_var_t tmpmask)
>>> {
>>> struct rdtgroup *prdtgrp = rdtgrp->mon.parent;
>>> + u32 closid, rmid;
>>> int cpu;
>>>
>>> /* Give any tasks back to the parent group */
>>> rdt_move_group_tasks(rdtgrp, prdtgrp, tmpmask);
>>>
>>> /* Update per cpu rmid of the moved CPUs first */
>>> + closid = rdtgrp->closid;
>>> + rmid = prdtgrp->mon.rmid;
>>> for_each_cpu(cpu, &rdtgrp->cpu_mask)
>>> - per_cpu(pqr_state.default_rmid, cpu) = prdtgrp->mon.rmid;
>>> + resctrl_arch_set_cpu_default_closid_rmid(cpu, closid, rmid);
>>> +
>>
>> While I understand that the CLOSIDs are the same, I do think it looks unexpected
>> for the CLOSID to be set to the CLOSID of the group being removed. Could this
>> be set to CLOSID of parent group instead?
>>
>> Reinette
>
> That seems reasonable. How about something like this?
>
> - closid = rdtgrp->closid;
> + closid = prdtgrp->closid; /* no change, but the arch code needs it */

Looks good. If the comment stays, please do replace the tail comment with a
freestanding comment (for reference you can search for "No tail comments"
in Documentation/process/maintainer-tip.rst).

Thank you

Reinette