linux-kernel - Re: [PATCH V2 1/4] x86/resctrl: Use IPI instead of task_work_add() to update PQR

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Message-ID: <516cbcf4-ec80-a81a-c5f4-971fba4b2972@intel.com>
Date:   Thu, 7 Jan 2021 14:11:07 -0800
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     tglx@...utronix.de, fenghua.yu@...el.com, tony.luck@...el.com,
        kuo-lang.tseng@...el.com, shakeelb@...gle.com,
        valentin.schneider@....com, mingo@...hat.com, babu.moger@....com,
        james.morse@....com, hpa@...or.com, x86@...nel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH V2 1/4] x86/resctrl: Use IPI instead of task_work_add() to
 update PQR_ASSOC MSR

Hi Borislav,

On 1/6/2021 3:19 AM, Borislav Petkov wrote:
> On Thu, Dec 17, 2020 at 02:31:18PM -0800, Reinette Chatre wrote:
>> +#ifdef CONFIG_SMP
>> +static void update_task_closid_rmid(struct task_struct *t)
>> +{
>> +	if (task_curr(t))
>> +		smp_call_function_single(task_cpu(t), _update_task_closid_rmid,
>> +					 t, 1);
>>   }
>> +#else
>> +static void update_task_closid_rmid(struct task_struct *t)
>> +{
>> +	_update_task_closid_rmid(t);
>> +}
>> +#endif
> 
> Why the ifdeffery? Why not simply:
> 
> static void update_task_closid_rmid(struct task_struct *t)
> {
>          if (IS_ENABLED(CONFIG_SMP) && task_curr(t))
>                  smp_call_function_single(task_cpu(t), _update_task_closid_rmid, t, 1);
>          else
>                  _update_task_closid_rmid(t);
> }
> 
> ?
> 
> If no particular reason, I'll change it before committing.

There is no particular reason. What you propose is much more readable.
Thank you very much.

Reinette