linux-kernel - Re: [PATCH v15 26/34] fs/resctrl: Add event configuration directory under info/L3

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Message-ID: <2028b020-bb31-421c-b7d8-acb9ac7e9f77@intel.com>
Date: Thu, 17 Jul 2025 20:54:49 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Babu Moger <babu.moger@....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 v15 26/34] fs/resctrl: Add event configuration directory
 under info/L3_MON/

Hi Babu,

On 7/8/25 3:17 PM, Babu Moger wrote:
> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
> index 15d10c346307..bb28ef7e4600 100644
> --- a/fs/resctrl/rdtgroup.c
> +++ b/fs/resctrl/rdtgroup.c
> @@ -86,6 +86,8 @@ enum resctrl_event_id mba_mbps_default_event;
>  
>  static bool resctrl_debug;
>  
> +extern struct mbm_transaction mbm_transactions[NUM_MBM_TRANSACTIONS];
> +

Please move this extern to fs/resctrl/internal.h.

>  void rdt_last_cmd_clear(void)
>  {
>  	lockdep_assert_held(&rdtgroup_mutex);
> @@ -1895,6 +1897,25 @@ static int resctrl_available_mbm_cntrs_show(struct kernfs_open_file *of,
>  	return ret;
>  }
>  
> +static int event_filter_show(struct kernfs_open_file *of, struct seq_file *seq, void *v)
> +{
> +	struct mon_evt *mevt = rdt_kn_parent_priv(of->kn);
> +	bool sep = false;
> +	int i;
> +
> +	for (i = 0; i < NUM_MBM_TRANSACTIONS; i++) {
> +		if (mevt->evt_cfg & mbm_transactions[i].val) {

mevt->evt_cfg could possibly be changed concurrently. This should
be protected with the rdtgroup_mutex.

> +			if (sep)
> +				seq_putc(seq, ',');
> +			seq_printf(seq, "%s", mbm_transactions[i].name);
> +			sep = true;
> +		}
> +	}
> +	seq_putc(seq, '\n');
> +
> +	return 0;
> +}
> +
>  /* rdtgroup information files for one cache resource. */
>  static struct rftype res_common_files[] = {
>  	{
> @@ -2019,6 +2040,12 @@ static struct rftype res_common_files[] = {
>  		.seq_show	= mbm_local_bytes_config_show,
>  		.write		= mbm_local_bytes_config_write,
>  	},
> +	{
> +		.name		= "event_filter",
> +		.mode		= 0444,
> +		.kf_ops		= &rdtgroup_kf_single_ops,
> +		.seq_show	= event_filter_show,
> +	},
>  	{
>  		.name		= "mbm_assign_mode",
>  		.mode		= 0444,
> @@ -2279,10 +2306,48 @@ int rdtgroup_kn_mode_restore(struct rdtgroup *r, const char *name,
>  	return ret;
>  }
>  
> +static int resctrl_mkdir_event_configs(struct rdt_resource *r, struct kernfs_node *l3_mon_kn)
> +{
> +	struct kernfs_node *kn_subdir, *kn_subdir2;
> +	struct mon_evt *mevt;
> +	int ret;
> +
> +	kn_subdir = kernfs_create_dir(l3_mon_kn, "event_configs", l3_mon_kn->mode, NULL);
> +	if (IS_ERR(kn_subdir))
> +		return PTR_ERR(kn_subdir);
> +
> +	ret = rdtgroup_kn_set_ugid(kn_subdir);
> +	if (ret)
> +		return ret;
> +
> +	for_each_mon_event(mevt) {
> +		if (mevt->rid != r->rid || !mevt->enabled || !resctrl_is_mbm_event(mevt->evtid))
> +			continue;
> +
> +		kn_subdir2 = kernfs_create_dir(kn_subdir, mevt->name, kn_subdir->mode, mevt);
> +		if (IS_ERR(kn_subdir2)) {
> +			ret = PTR_ERR(kn_subdir2);
> +			goto out_config;
> +		}
> +
> +		ret = rdtgroup_kn_set_ugid(kn_subdir2);
> +		if (ret)
> +			goto out_config;
> +
> +		ret = rdtgroup_add_files(kn_subdir2, RFTYPE_ASSIGN_CONFIG);
> +		if (ret)
> +			break;
> +	}
> +
> +out_config:
> +	return ret;

No "config" is happening here so the goto label can just be "out".

> +}
> +
>  static int rdtgroup_mkdir_info_resdir(void *priv, char *name,
>  				      unsigned long fflags)
>  {
>  	struct kernfs_node *kn_subdir;
> +	struct rdt_resource *r;
>  	int ret;
>  
>  	kn_subdir = kernfs_create_dir(kn_info, name,
  

Reinette