linux-kernel - Re: [PATCH v3 2/7] x86/resctrl: Remove few unnecessary rftype flags

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Message-ID: <c07dfb04-4502-47d8-ad89-9f9c7898f246@amd.com>
Date:   Thu, 16 Mar 2023 16:11:09 -0500
From:   "Moger, Babu" <babu.moger@....com>
To:     Reinette Chatre <reinette.chatre@...el.com>, corbet@....net,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de
Cc:     fenghua.yu@...el.com, dave.hansen@...ux.intel.com, x86@...nel.org,
        hpa@...or.com, paulmck@...nel.org, akpm@...ux-foundation.org,
        quic_neeraju@...cinc.com, rdunlap@...radead.org,
        damien.lemoal@...nsource.wdc.com, songmuchun@...edance.com,
        peterz@...radead.org, jpoimboe@...nel.org, pbonzini@...hat.com,
        chang.seok.bae@...el.com, pawan.kumar.gupta@...ux.intel.com,
        jmattson@...gle.com, daniel.sneddon@...ux.intel.com,
        sandipan.das@....com, tony.luck@...el.com, james.morse@....com,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        bagasdotme@...il.com, eranian@...gle.com,
        christophe.leroy@...roup.eu, jarkko@...nel.org,
        adrian.hunter@...el.com, quic_jiles@...cinc.com,
        peternewman@...gle.com
Subject: Re: [PATCH v3 2/7] x86/resctrl: Remove few unnecessary rftype flags

Hi Reinette,

On 3/16/23 15:41, Reinette Chatre wrote:
> Hi Babu,
> 
> On 3/16/2023 1:31 PM, Moger, Babu wrote:
>> On 3/15/23 13:33, Reinette Chatre wrote:
>>> On 3/2/2023 12:24 PM, Babu Moger wrote:
>>>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>>>> index 15ea5b550fe9..3c86506e54c1 100644
>>>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>>>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>>>> @@ -3163,7 +3163,7 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
>>>>  {
>>>>  	struct rdtgroup *prdtgrp, *rdtgrp;
>>>>  	struct kernfs_node *kn;
>>>> -	uint files = 0;
>>>> +	uint fflags = 0;
>>>
>>> Hoe does changing the variable name from "files" to "fflags" simplify
>>> the code?
>>
>> I should have said readability of the code. Its actually fflags we are
>> passing to rdtgroup_add_files. While changing flags below, I changed the
>> variable name to fflags.
> 
> You are correct in that it is the actual fflags parameter but what it
> reflects is which files will be created. I do not find that using "files"
> makes the code unreadable. 

Everything helps. I changed it because I was already changing few things
in this function. That is not the only change in this function. Here is
the main change in this function.

-	files = RFTYPE_BASE | BIT(RF_CTRLSHIFT + rtype);
-	ret = rdtgroup_add_files(kn, files);
+	if (rtype == RDTCTRL_GROUP)
+		fflags = RFTYPE_BASE | RFTYPE_CTRL;
+	else
+		fflags = RFTYPE_BASE | RFTYPE_MON;
+
+	ret = rdtgroup_add_files(kn, fflags);

In my opinion this is more clearer. Also I can delete some of these
un-necessary definitions below.

 #define RFTYPE_INFO			BIT(0)
 #define RFTYPE_BASE			BIT(1)
-#define RF_CTRLSHIFT			4
-#define RF_MONSHIFT			5
-#define RF_TOPSHIFT			6
-#define RFTYPE_CTRL			BIT(RF_CTRLSHIFT)
-#define RFTYPE_MON			BIT(RF_MONSHIFT)
-#define RFTYPE_TOP			BIT(RF_TOPSHIFT)
+#define RFTYPE_CTRL			BIT(4)
+#define RFTYPE_MON			BIT(5)
+#define RFTYPE_TOP			BIT(6)

Thanks
Babu