linux-kernel - Re: [PATCH v4 2/2] x86/resctrl: Read supported bandwidth sources using CPUID command

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Message-ID: <920e6d40-78d8-4e98-8f85-6d015681887f@intel.com>
Date: Fri, 12 Jan 2024 13:24:07 -0800
From: Reinette Chatre <reinette.chatre@...el.com>
To: <babu.moger@....com>, <corbet@....net>, <fenghua.yu@...el.com>,
	<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>
CC: <x86@...nel.org>, <hpa@...or.com>, <paulmck@...nel.org>,
	<rdunlap@...radead.org>, <tj@...nel.org>, <peterz@...radead.org>,
	<seanjc@...gle.com>, <kim.phillips@....com>, <jmattson@...gle.com>,
	<ilpo.jarvinen@...ux.intel.com>, <jithu.joseph@...el.com>,
	<kan.liang@...ux.intel.com>, <nikunj@....com>,
	<daniel.sneddon@...ux.intel.com>, <pbonzini@...hat.com>,
	<rick.p.edgecombe@...el.com>, <rppt@...nel.org>,
	<maciej.wieczor-retman@...el.com>, <linux-doc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <eranian@...gle.com>,
	<peternewman@...gle.com>, <dhagiani@....com>
Subject: Re: [PATCH v4 2/2] x86/resctrl: Read supported bandwidth sources
 using CPUID command

Hi Babu,

On 1/12/2024 12:38 PM, Moger, Babu wrote:
> Hi  Reinette,
> 
> On 1/12/2024 1:02 PM, Reinette Chatre wrote:
>> Hi Babu,
>>
>> On 1/11/2024 1:36 PM, Babu Moger wrote:
>>
>>> @@ -1686,6 +1681,13 @@ static int mon_config_write(struct rdt_resource *r, char *tok, u32 evtid)
>>>           return -EINVAL;
>>>       }
>>>   +    /* mon_config cannot be more than the supported set of events */
>> copy&paste error? There is no mon_config in this function.
> Yea. it should be mbm_cfg_mask.  Will fix it.

I do not think it is correct to replace mon_config with mbm_cfg_mask. Is this comment
not referring to the user provided value (that is checked against mbm_cfg_mask)? So
perhaps something like:

	 /* Check value from user against supported events. */
	or
	 /* Value from user cannot be more than the supported set of events. */

Please feel free to improve.

>>
>> (copy&paste difficulties reminds me of [1])
>>
>>> +    if ((val & hw_res->mbm_cfg_mask) != val) {
>>> +        rdt_last_cmd_printf("Invalid event configuration: The maximum valid "
>>> +                    "bitmask is 0x%02x\n", hw_res->mbm_cfg_mask);
>> checkpatch.pl should have warned about this split of text across two lines.
>> Logging functions and single strings are allowed to exceed the max line length.
>> If you just merge the two lines then checkpatch.pl may still warn for resctrl strings
>> but that is because it does not recognize rdt_last_cmd_printf() as a logging function.
>>
>> You can also just shorten the string so this patch passes the checkpatch.pl check.
>> For example,
>> "Invalid event configuration: maximum valid mask is 0x%02x\n"
>> or
>> "Invalid event configuration: maximum is 0x%02x\n"
>> or ?
> 
> Yes. Checkpatch reported error when I split the text.
> 
> How about this?. Checkpatch is happy.
> 
> rdt_last_cmd_printf("Invalid event configuration: max valid mask is 0x%02x\n",
> +                                   hw_res->mbm_cfg_mask);
> 

Looks good.

Reinette