linux-kernel - [PATCH v6 28/30] fs/resctrl: Provide interface to create a debugfs info directory

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Message-ID: <20250626164941.106341-29-tony.luck@intel.com>
Date: Thu, 26 Jun 2025 09:49:37 -0700
From: Tony Luck <tony.luck@...el.com>
To: Fenghua Yu <fenghuay@...dia.com>,
	Reinette Chatre <reinette.chatre@...el.com>,
	Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>,
	Peter Newman <peternewman@...gle.com>,
	James Morse <james.morse@....com>,
	Babu Moger <babu.moger@....com>,
	Drew Fustini <dfustini@...libre.com>,
	Dave Martin <Dave.Martin@....com>,
	Anil Keshavamurthy <anil.s.keshavamurthy@...el.com>,
	Chen Yu <yu.c.chen@...el.com>
Cc: x86@...nel.org,
	linux-kernel@...r.kernel.org,
	patches@...ts.linux.dev,
	Tony Luck <tony.luck@...el.com>
Subject: [PATCH v6 28/30] fs/resctrl: Provide interface to create a debugfs info directory

Architectures are constrained to just the file interfaces provided by
the file system for each resource. This does not allow for architecture
specific debug interfaces.

Add resctrl_debugfs_mon_info_mkdir() which creates a directory in the
debugfs file system for a resource. Naming follows the layout of the
main resctrl hierarchy:

	/sys/kernel/debug/resctrl/info/{resource}_MON

Suggested-by: Reinette Chatre <reinette.chatre@...el.com>
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
 include/linux/resctrl.h |  6 ++++++
 fs/resctrl/rdtgroup.c   | 24 ++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 35ae24822493..a8ffd9f61c46 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -569,6 +569,12 @@ void resctrl_arch_reset_all_ctrls(struct rdt_resource *r);
 extern unsigned int resctrl_rmid_realloc_threshold;
 extern unsigned int resctrl_rmid_realloc_limit;
 
+/**
+ * resctrl_debugfs_mon_info_arch_mkdir() - Create a debugfs info directory.
+ * @r:	Resource (must be mon_capable).
+ */
+struct dentry *resctrl_debugfs_mon_info_arch_mkdir(struct rdt_resource *r);
+
 int resctrl_init(void);
 void resctrl_exit(void);
 
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 3d87e6c4c600..511362a67532 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -24,6 +24,7 @@
 #include <linux/sched/task.h>
 #include <linux/slab.h>
 #include <linux/user_namespace.h>
+#include <linux/utsname.h>
 
 #include <uapi/linux/magic.h>
 
@@ -4350,6 +4351,29 @@ int resctrl_init(void)
 	return ret;
 }
 
+/*
+ * Create /sys/kernel/debug/resctrl/info/{r->name}_MON/arch directory
+ * by request for architecture to use.
+ */
+struct dentry *resctrl_debugfs_mon_info_arch_mkdir(struct rdt_resource *r)
+{
+	static struct dentry *debugfs_resctrl_info;
+	struct dentry *moninfodir;
+	char name[32];
+
+	if (!r->mon_capable)
+		return NULL;
+
+	if (!debugfs_resctrl_info)
+		debugfs_resctrl_info = debugfs_create_dir("info", debugfs_resctrl);
+
+	sprintf(name, "%s_MON", r->name);
+
+	moninfodir =  debugfs_create_dir(name, debugfs_resctrl_info);
+
+	return debugfs_create_dir(utsname()->machine, moninfodir);
+}
+
 static bool resctrl_online_domains_exist(void)
 {
 	struct rdt_resource *r;
-- 
2.49.0