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Message-Id: <20250414-reftrack-dbgfs-v1-2-f03585832203@kernel.org>
Date: Mon, 14 Apr 2025 10:45:47 -0400
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>
Cc: Qasim Ijaz <qasdev00@...il.com>, Nathan Chancellor <nathan@...nel.org>,
Andrew Lunn <andrew@...n.ch>, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org, Jeff Layton <jlayton@...nel.org>
Subject: [PATCH 2/4] ref_tracker: add ability to 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. Add a new function that other
subsystems can optionally call to update the name field in the
ref_tracker_dir and register a corresponding seq_file for it in the
top-level ref_tracker directory.
Also, alter the pr_ostream infrastructure to allow the caller to specify
a seq_file to which the output should go instead of printing to an
arbitrary buffer or the kernel's ring buffer.
Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
include/linux/ref_tracker.h | 13 +++++++
lib/ref_tracker.c | 84 +++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 94 insertions(+), 3 deletions(-)
diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h
index 8eac4f3d52547ccbaf9dcd09962ce80d26fbdff8..77a55a32c067216fa02ba349498f53bd289aee0c 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;
@@ -17,6 +18,9 @@ struct ref_tracker_dir {
bool dead;
struct list_head list; /* List of active trackers */
struct list_head quarantine; /* List of dead trackers */
+#ifdef CONFIG_DEBUG_FS
+ struct dentry *dentry;
+#endif
char name[32];
#endif
};
@@ -34,10 +38,15 @@ static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
dir->dead = false;
refcount_set(&dir->untracked, 1);
refcount_set(&dir->no_tracker, 1);
+#ifdef CONFIG_DEBUG_FS
+ dir->dentry = NULL;
+#endif
strscpy(dir->name, name, sizeof(dir->name));
stack_depot_init();
}
+void ref_tracker_dir_debugfs(struct ref_tracker_dir *dir, const char *name);
+
void ref_tracker_dir_exit(struct ref_tracker_dir *dir);
void ref_tracker_dir_print_locked(struct ref_tracker_dir *dir,
@@ -62,6 +71,10 @@ static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
{
}
+static inline void ref_tracker_dir_debugfs(struct ref_tracker_dir *dir, const char *name)
+{
+}
+
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 c96994134fe1ddfcbf644cc75b36b7e94461ec48..10452f66283b081460ef7f4f5640e30487bb1595 100644
--- a/lib/ref_tracker.c
+++ b/lib/ref_tracker.c
@@ -8,6 +8,7 @@
#include <linux/slab.h>
#include <linux/stacktrace.h>
#include <linux/stackdepot.h>
+#include <linux/seq_file.h>
#define REF_TRACKER_STACK_ENTRIES 16
#define STACK_BUF_SIZE 1024
@@ -30,6 +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)
{
@@ -66,6 +75,7 @@ ref_tracker_get_stats(struct ref_tracker_dir *dir, unsigned int limit)
struct ostream {
char *buf;
+ struct seq_file *seq;
int size, used;
};
@@ -73,7 +83,9 @@ struct ostream {
({ \
struct ostream *_s = (stream); \
\
- if (!_s->buf) { \
+ if (_s->seq) { \
+ seq_printf(_s->seq, fmt, ##args); \
+ } else if (!_s->buf) { \
pr_err(fmt, ##args); \
} else { \
int ret, len = _s->size - _s->used; \
@@ -163,6 +175,7 @@ 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);
@@ -279,7 +292,72 @@ EXPORT_SYMBOL_GPL(ref_tracker_free);
#ifdef CONFIG_DEBUG_FS
#include <linux/debugfs.h>
-static int __init ref_tracker_debug_init(void)
+static int ref_tracker_dir_seq_print(struct ref_tracker_dir *dir, struct seq_file *seq)
+{
+ struct ostream os = { .seq = seq };
+ unsigned long flags;
+
+ spin_lock_irqsave(&dir->lock, flags);
+ __ref_tracker_dir_pr_ostream(dir, 16, &os);
+ spin_unlock_irqrestore(&dir->lock, flags);
+
+ 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 finalize
+ * @name: updated name of the ref_tracker_dir
+ *
+ * In some cases, the name given to a ref_tracker_dir is based on incomplete information,
+ * and may not be unique. Call this to finalize the name of @dir, and create a debugfs
+ * file for it.
+ */
+void ref_tracker_dir_debugfs(struct ref_tracker_dir *dir, const char *name)
+{
+ strscpy(dir->name, name, sizeof(dir->name));
+
+ if (ref_tracker_debug_dir) {
+ dir->dentry = debugfs_create_file(dir->name, S_IFREG | 0400,
+ ref_tracker_debug_dir, dir,
+ &ref_tracker_debugfs_fops);
+ if (IS_ERR(dir->dentry)) {
+ pr_warn("ref_tracker: unable to create debugfs file for %s: %pe\n",
+ dir->name, dir->dentry);
+ dir->dentry = NULL;
+ }
+ }
+}
+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);
if (IS_ERR(ref_tracker_debug_dir)) {
@@ -289,5 +367,5 @@ static int __init ref_tracker_debug_init(void)
}
return 0;
}
-late_initcall(ref_tracker_debug_init);
+late_initcall(ref_tracker_debugfs_init);
#endif /* CONFIG_DEBUG_FS */
--
2.49.0
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