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Message-Id: <20250610-reftrack-dbgfs-v14-7-efb532861428@kernel.org>
Date: Tue, 10 Jun 2025 10:59:27 -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>,
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: Krzysztof Karas <krzysztof.karas@...el.com>,
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 v14 7/9] ref_tracker: add a way to create a symlink to the
ref_tracker_dir debugfs file
Add the ability for a subsystem to add a user-friendly symlink that
points to a ref_tracker_dir's debugfs file. Add a separate
debugfs_symlinks xarray and use that to track symlinks. The reaper
workqueue job will remove symlinks before their corresponding dentries.
Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
include/linux/ref_tracker.h | 11 +++++++++++
lib/ref_tracker.c | 47 +++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 58 insertions(+)
diff --git a/include/linux/ref_tracker.h b/include/linux/ref_tracker.h
index 28bbf436a8f4646cfac181d618195a9460bda196..e1323de93bf6b891aa14ad8d9b4b28d02e10f9f7 100644
--- a/include/linux/ref_tracker.h
+++ b/include/linux/ref_tracker.h
@@ -29,6 +29,7 @@ struct ref_tracker_dir {
#ifdef CONFIG_DEBUG_FS
void ref_tracker_dir_debugfs(struct ref_tracker_dir *dir);
+void ref_tracker_dir_symlink(struct ref_tracker_dir *dir, const char *fmt, ...);
#else /* CONFIG_DEBUG_FS */
@@ -36,6 +37,11 @@ static inline void ref_tracker_dir_debugfs(struct ref_tracker_dir *dir)
{
}
+static inline __ostream_printf
+void ref_tracker_dir_symlink(struct ref_tracker_dir *dir, const char *fmt, ...)
+{
+}
+
#endif /* CONFIG_DEBUG_FS */
static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
@@ -85,6 +91,11 @@ static inline void ref_tracker_dir_debugfs(struct ref_tracker_dir *dir)
{
}
+static inline __ostream_printf
+void ref_tracker_dir_symlink(struct ref_tracker_dir *dir, const char *fmt, ...)
+{
+}
+
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 4f1c4fe5e6b1274b6aeb733a3f8c06d1dff003f5..a78741308a2c2dc7aff65519970ad081b59e0de5 100644
--- a/lib/ref_tracker.c
+++ b/lib/ref_tracker.c
@@ -44,11 +44,13 @@ struct ref_tracker_dir_stats {
* dentries asynchronously.
*/
static struct xarray debugfs_dentries;
+static struct xarray debugfs_symlinks;
static struct work_struct debugfs_reap_worker;
#define REF_TRACKER_DIR_DEAD XA_MARK_0
static inline void ref_tracker_debugfs_mark(struct ref_tracker_dir *dir)
{
+ xa_set_mark(&debugfs_symlinks, (unsigned long)dir, REF_TRACKER_DIR_DEAD);
xa_set_mark(&debugfs_dentries, (unsigned long)dir, REF_TRACKER_DIR_DEAD);
schedule_work(&debugfs_reap_worker);
}
@@ -446,6 +448,45 @@ void ref_tracker_dir_debugfs(struct ref_tracker_dir *dir)
}
EXPORT_SYMBOL(ref_tracker_dir_debugfs);
+void __ostream_printf ref_tracker_dir_symlink(struct ref_tracker_dir *dir, const char *fmt, ...)
+{
+ char name[NAME_MAX + 1];
+ struct dentry *symlink, *dentry;
+ va_list args;
+ int ret;
+
+ symlink = xa_load(&debugfs_symlinks, (unsigned long)dir);
+ dentry = xa_load(&debugfs_dentries, (unsigned long)dir);
+
+ /* Already created?*/
+ if (symlink && !xa_is_err(symlink))
+ return;
+
+ if (!dentry || xa_is_err(dentry))
+ return;
+
+ va_start(args, fmt);
+ ret = vsnprintf(name, sizeof(name), fmt, args);
+ va_end(args);
+ name[sizeof(name) - 1] = '\0';
+
+ if (ret < sizeof(name)) {
+ symlink = debugfs_create_symlink(name, ref_tracker_debug_dir,
+ dentry->d_name.name);
+ if (!IS_ERR(symlink)) {
+ void *old;
+
+ old = xa_store(&debugfs_symlinks, (unsigned long)dir,
+ symlink, GFP_KERNEL);
+ if (xa_is_err(old))
+ debugfs_remove(symlink);
+ else
+ WARN_ON_ONCE(old);
+ }
+ }
+}
+EXPORT_SYMBOL(ref_tracker_dir_symlink);
+
static void debugfs_reap_work(struct work_struct *work)
{
struct dentry *dentry;
@@ -454,6 +495,11 @@ static void debugfs_reap_work(struct work_struct *work)
do {
reaped = false;
+ xa_for_each_marked(&debugfs_symlinks, index, dentry, REF_TRACKER_DIR_DEAD) {
+ xa_erase(&debugfs_symlinks, index);
+ debugfs_remove(dentry);
+ reaped = true;
+ }
xa_for_each_marked(&debugfs_dentries, index, dentry, REF_TRACKER_DIR_DEAD) {
xa_erase(&debugfs_dentries, index);
debugfs_remove(dentry);
@@ -466,6 +512,7 @@ static int __init ref_tracker_debugfs_init(void)
{
INIT_WORK(&debugfs_reap_worker, debugfs_reap_work);
xa_init_flags(&debugfs_dentries, XA_FLAGS_LOCK_IRQ);
+ xa_init_flags(&debugfs_symlinks, XA_FLAGS_LOCK_IRQ);
ref_tracker_debug_dir = debugfs_create_dir("ref_tracker", NULL);
return 0;
}
--
2.49.0
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