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Message-ID: <20250521225049.132551-28-tony.luck@intel.com>
Date: Wed, 21 May 2025 15:50:45 -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 v5 27/29] fs/resctrl: Add file system mechanism for architecture info file
Creation of all files in the resctrl file system is under control of
the file system layer.
But some resources may need to add a file to the info/{resource}
directory for debug purposes.
Add a new rdt_resource::info_file field for the resource to specify
show() and/or write() operations. These will be called with the
rdtgroup_mutex held.
Architecture can note the file is only for debug using by setting
the rftype::flags RFTYPE_DEBUG bit.
Signed-off-by: Tony Luck <tony.luck@...el.com>
---
include/linux/resctrl.h | 33 +++++++++++++++++++++++++++
fs/resctrl/internal.h | 31 ++-----------------------
fs/resctrl/rdtgroup.c | 50 ++++++++++++++++++++++++++++++++++++++---
3 files changed, 82 insertions(+), 32 deletions(-)
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index b7e15abcde23..e067007c633c 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -73,6 +73,37 @@ enum resctrl_conf_type {
#define CDP_NUM_TYPES (CDP_DATA + 1)
+/**
+ * struct rftype - describe each file in the resctrl file system
+ * @name: File name
+ * @mode: Access mode
+ * @kf_ops: File operations
+ * @flags: File specific RFTYPE_FLAGS_* flags
+ * @fflags: File specific RFTYPE_* flags
+ * @seq_show: Show content of the file
+ * @write: Write to the file
+ */
+struct rftype {
+ char *name;
+ umode_t mode;
+ const struct kernfs_ops *kf_ops;
+ unsigned long flags;
+ unsigned long fflags;
+
+ int (*seq_show)(struct kernfs_open_file *of,
+ struct seq_file *sf, void *v);
+ /*
+ * write() is the generic write callback which maps directly to
+ * kernfs write operation and overrides all other operations.
+ * Maximum write size is determined by ->max_write_len.
+ */
+ ssize_t (*write)(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off);
+};
+
+/* Only rftype::flags option available to architecture code */
+#define RFTYPE_DEBUG BIT(10)
+
/*
* struct pseudo_lock_region - pseudo-lock region information
* @s: Resctrl schema for the resource to which this
@@ -281,6 +312,7 @@ enum resctrl_schema_fmt {
* @mbm_cfg_mask: Bandwidth sources that can be tracked when bandwidth
* monitoring events can be configured.
* @cdp_capable: Is the CDP feature available on this resource
+ * @info_file: Optional per-resource debug info file
*/
struct rdt_resource {
int rid;
@@ -297,6 +329,7 @@ struct rdt_resource {
enum resctrl_schema_fmt schema_fmt;
unsigned int mbm_cfg_mask;
bool cdp_capable;
+ struct rftype info_file;
};
/*
diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
index 1f4800cfcd6a..f13b63804c1a 100644
--- a/fs/resctrl/internal.h
+++ b/fs/resctrl/internal.h
@@ -232,7 +232,8 @@ struct rdtgroup {
#define RFTYPE_RES_MB BIT(9)
-#define RFTYPE_DEBUG BIT(10)
+// RFTYPE_DEBUG available to architecture code in <linux/resctrl.h>
+//#define RFTYPE_DEBUG BIT(10)
#define RFTYPE_RES_PERF_PKG BIT(11)
@@ -251,34 +252,6 @@ extern struct list_head rdt_all_groups;
extern int max_name_width;
-/**
- * struct rftype - describe each file in the resctrl file system
- * @name: File name
- * @mode: Access mode
- * @kf_ops: File operations
- * @flags: File specific RFTYPE_FLAGS_* flags
- * @fflags: File specific RFTYPE_* flags
- * @seq_show: Show content of the file
- * @write: Write to the file
- */
-struct rftype {
- char *name;
- umode_t mode;
- const struct kernfs_ops *kf_ops;
- unsigned long flags;
- unsigned long fflags;
-
- int (*seq_show)(struct kernfs_open_file *of,
- struct seq_file *sf, void *v);
- /*
- * write() is the generic write callback which maps directly to
- * kernfs write operation and overrides all other operations.
- * Maximum write size is determined by ->max_write_len.
- */
- ssize_t (*write)(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off);
-};
-
/**
* struct mbm_state - status for each MBM counter in each domain
* @prev_bw_bytes: Previous bytes value read for bandwidth calculation
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index e212e46e0780..f09674c209f8 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -329,6 +329,37 @@ static const struct kernfs_ops rdtgroup_kf_single_ops = {
.seq_show = rdtgroup_seqfile_show,
};
+static int rdtgroup_seqfile_show_locked(struct seq_file *m, void *arg)
+{
+ struct kernfs_open_file *of = m->private;
+ struct rftype *rft = of->kn->priv;
+
+ guard(mutex)(&rdtgroup_mutex);
+
+ if (rft->seq_show)
+ return rft->seq_show(of, m, arg);
+ return 0;
+}
+
+static ssize_t rdtgroup_file_write_locked(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct rftype *rft = of->kn->priv;
+
+ guard(mutex)(&rdtgroup_mutex);
+
+ if (rft->write)
+ return rft->write(of, buf, nbytes, off);
+
+ return -EINVAL;
+}
+
+static const struct kernfs_ops rdtgroup_kf_single_locked_ops = {
+ .atomic_write_len = PAGE_SIZE,
+ .write = rdtgroup_file_write_locked,
+ .seq_show = rdtgroup_seqfile_show_locked,
+};
+
static const struct kernfs_ops kf_mondata_ops = {
.atomic_write_len = PAGE_SIZE,
.seq_show = rdtgroup_mondata_show,
@@ -2162,7 +2193,7 @@ int rdtgroup_kn_mode_restore(struct rdtgroup *r, const char *name,
return ret;
}
-static int rdtgroup_mkdir_info_resdir(void *priv, char *name,
+static int rdtgroup_mkdir_info_resdir(struct rdt_resource *r, void *priv, char *name,
unsigned long fflags)
{
struct kernfs_node *kn_subdir;
@@ -2177,6 +2208,19 @@ static int rdtgroup_mkdir_info_resdir(void *priv, char *name,
if (ret)
return ret;
+ if (r->info_file.name &&
+ (!(r->info_file.flags & RFTYPE_DEBUG) || resctrl_debug)) {
+ r->info_file.mode = 0;
+ if (r->info_file.seq_show)
+ r->info_file.mode |= 0444;
+ if (r->info_file.write)
+ r->info_file.mode |= 0200;
+ r->info_file.kf_ops = &rdtgroup_kf_single_locked_ops;
+ ret = rdtgroup_add_file(kn_subdir, &r->info_file);
+ if (ret)
+ return ret;
+ }
+
ret = rdtgroup_add_files(kn_subdir, fflags);
if (!ret)
kernfs_activate(kn_subdir);
@@ -2221,7 +2265,7 @@ static int rdtgroup_create_info_dir(struct kernfs_node *parent_kn)
list_for_each_entry(s, &resctrl_schema_all, list) {
r = s->res;
fflags = fflags_from_resource(r) | RFTYPE_CTRL_INFO;
- ret = rdtgroup_mkdir_info_resdir(s, s->name, fflags);
+ ret = rdtgroup_mkdir_info_resdir(r, s, s->name, fflags);
if (ret)
goto out_destroy;
}
@@ -2229,7 +2273,7 @@ static int rdtgroup_create_info_dir(struct kernfs_node *parent_kn)
for_each_mon_capable_rdt_resource(r) {
fflags = fflags_from_resource(r) | RFTYPE_MON_INFO;
sprintf(name, "%s_MON", r->name);
- ret = rdtgroup_mkdir_info_resdir(r, name, fflags);
+ ret = rdtgroup_mkdir_info_resdir(r, r, name, fflags);
if (ret)
goto out_destroy;
}
--
2.49.0
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