linux-kernel - Re: [PATCH v16 31/34] fs/resctrl: Disable BMEC event configuration when mbm

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Message-ID: <c5d37c3d-f6d8-41e3-bc32-699c53de8152@amd.com>
Date: Tue, 12 Aug 2025 14:16:34 -0500
From: "Moger, Babu" <babu.moger@....com>
To: Reinette Chatre <reinette.chatre@...el.com>, corbet@....net,
 tony.luck@...el.com, james.morse@....com, tglx@...utronix.de,
 mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com
Cc: Dave.Martin@....com, x86@...nel.org, hpa@...or.com,
 akpm@...ux-foundation.org, paulmck@...nel.org, rostedt@...dmis.org,
 Neeraj.Upadhyay@....com, david@...hat.com, arnd@...db.de, fvdl@...gle.com,
 seanjc@...gle.com, jpoimboe@...nel.org, pawan.kumar.gupta@...ux.intel.com,
 xin@...or.com, manali.shukla@....com, tao1.su@...ux.intel.com,
 sohil.mehta@...el.com, kai.huang@...el.com, xiaoyao.li@...el.com,
 peterz@...radead.org, xin3.li@...el.com, kan.liang@...ux.intel.com,
 mario.limonciello@....com, thomas.lendacky@....com, perry.yuan@....com,
 gautham.shenoy@....com, chang.seok.bae@...el.com, linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org, peternewman@...gle.com, eranian@...gle.com
Subject: Re: [PATCH v16 31/34] fs/resctrl: Disable BMEC event configuration
 when mbm_event mode is enabled

Hi Reinette,

On 7/30/25 15:11, Reinette Chatre wrote:
> Hi Babu,
> 
> On 7/25/25 11:29 AM, Babu Moger wrote:
>> @@ -1799,6 +1800,41 @@ static ssize_t mbm_local_bytes_config_write(struct kernfs_open_file *of,
>>  	return ret ?: nbytes;
>>  }
>>  
>> +/*
>> + * resctrl_bmec_files_show() — Controls the visibility of BMEC-related resctrl
>> + * files. When @show is true, the files are displayed; when false, the files
>> + * are hidden.
>> + * Don't treat kernfs_find_and_get failure as an error, since this function may
>> + * be called regardless of whether BMEC is supported or the event is enabled.
>> + */
>> +static void resctrl_bmec_files_show(struct rdt_resource *r, struct kernfs_node *l3_mon_kn,
>> +				    bool show)
>> +{
>> +	struct kernfs_node *kn_config;
>> +	char name[32];
>> +
>> +	if (!l3_mon_kn) {
>> +		sprintf(name, "%s_MON", r->name);
>> +		l3_mon_kn = kernfs_find_and_get(kn_info, name);
>> +		if (!l3_mon_kn)
>> +			return;
>> +	}
>> +
>> +	kn_config = kernfs_find_and_get(l3_mon_kn, "mbm_total_bytes_config");
>> +	if (kn_config) {
>> +		kernfs_show(kn_config, show);
>> +		kernfs_put(kn_config);
>> +	}
>> +
>> +	kn_config = kernfs_find_and_get(l3_mon_kn, "mbm_local_bytes_config");
>> +	if (kn_config) {
>> +		kernfs_show(kn_config, show);
>> +		kernfs_put(kn_config);
>> +	}
>> +
>> +	kernfs_put(l3_mon_kn);
> 
> Looks like this will drop an extra reference if l3_mon_kn was provided as parameter.
> 

Yes. Fixed it now.
Thanks
Babu Moger