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Message-Id: <20250428-reftrack-dbgfs-v5-6-1cbbdf2038bd@kernel.org>
Date: Mon, 28 Apr 2025 11:26:29 -0700
From: Jeff Layton <jlayton@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>,
"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
Simon Horman <horms@...nel.org>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
Jani Nikula <jani.nikula@...ux.intel.com>,
Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
Rodrigo Vivi <rodrigo.vivi@...el.com>,
Tvrtko Ursulin <tursulin@...ulin.net>
Cc: Kuniyuki Iwashima <kuniyu@...zon.com>, Qasim Ijaz <qasdev00@...il.com>,
Nathan Chancellor <nathan@...nel.org>, Andrew Lunn <andrew@...n.ch>,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
Jeff Layton <jlayton@...nel.org>
Subject: [PATCH v5 06/10] ref_tracker: automatically register a file in
debugfs for a ref_tracker_dir
Currently, there is no convenient way to see the info that the
ref_tracking infrastructure collects. Attempt to create a file in
debugfs when called from ref_tracker_dir_init().
The file is given the name "class@%px", as having the unmodified address
is helpful for debugging. This should be safe since this directory is only
accessible by root
If debugfs file creation fails, a pr_warn will be isssued.
Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
include/linux/ref_tracker.h | 14 +++++++++
lib/ref_tracker.c | 72 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 86 insertions(+)
diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h
index 2adae128d4b5e45f156af4775a1d184bb596fa91..c6e65d7ef4d4fc74c60fcabd19166c131d4173e2 100644
--- a/include/linux/ref_tracker.h
+++ b/include/linux/ref_tracker.h
@@ -5,6 +5,7 @@
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/stackdepot.h>
+#include <linux/seq_file.h>
struct ref_tracker;
@@ -18,12 +19,17 @@ struct ref_tracker_dir {
struct list_head list; /* List of active trackers */
struct list_head quarantine; /* List of dead trackers */
const char *class; /* object classname */
+#ifdef CONFIG_DEBUG_FS
+ struct dentry *dentry;
+#endif
char name[32];
#endif
};
#ifdef CONFIG_REF_TRACKER
+void ref_tracker_dir_debugfs(struct ref_tracker_dir *dir);
+
static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
unsigned int quarantine_count,
const char *class,
@@ -37,7 +43,11 @@ static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
refcount_set(&dir->untracked, 1);
refcount_set(&dir->no_tracker, 1);
dir->class = class;
+#ifdef CONFIG_DEBUG_FS
+ dir->dentry = NULL;
+#endif
strscpy(dir->name, name, sizeof(dir->name));
+ ref_tracker_dir_debugfs(dir);
stack_depot_init();
}
@@ -66,6 +76,10 @@ static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
{
}
+static inline void ref_tracker_dir_debugfs(struct ref_tracker_dir *dir)
+{
+}
+
static inline void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
{
}
diff --git a/lib/ref_tracker.c b/lib/ref_tracker.c
index 4857bcb6d4bf557a0089f51328e75e8209e959e6..f5424857b0fde2339cce31c6744fd4dafbaf0d2a 100644
--- a/lib/ref_tracker.c
+++ b/lib/ref_tracker.c
@@ -31,6 +31,14 @@ struct ref_tracker_dir_stats {
} stacks[];
};
+#ifdef CONFIG_DEBUG_FS
+static void ref_tracker_debugfs_remove(struct ref_tracker_dir *dir);
+#else
+static inline void ref_tracker_debugfs_remove(struct ref_tracker_dir *dir)
+{
+}
+#endif
+
static struct ref_tracker_dir_stats *
ref_tracker_get_stats(struct ref_tracker_dir *dir, unsigned int limit)
{
@@ -197,6 +205,7 @@ void ref_tracker_dir_exit(struct ref_tracker_dir *dir)
bool leak = false;
dir->dead = true;
+ ref_tracker_debugfs_remove(dir);
spin_lock_irqsave(&dir->lock, flags);
list_for_each_entry_safe(tracker, n, &dir->quarantine, head) {
list_del(&tracker->head);
@@ -327,6 +336,69 @@ static int ref_tracker_dir_seq_print(struct ref_tracker_dir *dir, struct seq_fil
return os.used;
}
+static int ref_tracker_debugfs_show(struct seq_file *f, void *v)
+{
+ struct ref_tracker_dir *dir = f->private;
+
+ return ref_tracker_dir_seq_print(dir, f);
+}
+
+static int ref_tracker_debugfs_open(struct inode *inode, struct file *filp)
+{
+ struct ref_tracker_dir *dir = inode->i_private;
+
+ return single_open(filp, ref_tracker_debugfs_show, dir);
+}
+
+static const struct file_operations ref_tracker_debugfs_fops = {
+ .owner = THIS_MODULE,
+ .open = ref_tracker_debugfs_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+/**
+ * ref_tracker_dir_debugfs - create debugfs file for ref_tracker_dir
+ * @dir: ref_tracker_dir to be associated with debugfs file
+ * @fmt: format string for filename
+ * @...: arguments for the format string
+ *
+ * Call this function to create a debugfs file for your ref_tracker_dir that
+ * displays the current refcounts for the object. It will be automatically
+ * removed when the ref_tracker_dir exits. The filename must be unique. If
+ * the creation fails then the pr_warn will be emitted.
+ */
+void ref_tracker_dir_debugfs(struct ref_tracker_dir *dir)
+{
+ char name[NAME_MAX + 1];
+ int ret;
+
+ /* No-op if already created */
+ if (!IS_ERR_OR_NULL(dir->dentry))
+ return;
+
+ ret = snprintf(name, sizeof(name), "%s@%px", dir->class, dir);
+ name[sizeof(name) - 1] = '\0';
+
+ if (ret < sizeof(name))
+ dir->dentry = debugfs_create_file(name, S_IFREG | 0400,
+ ref_tracker_debug_dir, dir,
+ &ref_tracker_debugfs_fops);
+ else
+ dir->dentry = ERR_PTR(-ENAMETOOLONG);
+
+ if (IS_ERR(dir->dentry))
+ pr_warn("ref_tracker: unable to create debugfs file for %s: %pe\n",
+ name, dir->dentry);
+}
+EXPORT_SYMBOL(ref_tracker_dir_debugfs);
+
+static void ref_tracker_debugfs_remove(struct ref_tracker_dir *dir)
+{
+ debugfs_remove(dir->dentry);
+}
+
static int __init ref_tracker_debugfs_init(void)
{
ref_tracker_debug_dir = debugfs_create_dir("ref_tracker", NULL);
--
2.49.0
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