ref_tracker: eliminate the ref_tracker_dir name field

Now that we have dentries and the ability to create meaningful symlinks
to them, don't keep a name string in each tracker. Switch the output
format to print "class@address", and drop the name field.

Also, add a kerneldoc header for ref_tracker_dir_init().

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://patch.msgid.link/20250618-reftrack-dbgfs-v15-9-24fc37ead144@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/gpu/drm/display/drm_dp_tunnel.c

@@ -1920,7 +1920,7 @@ drm_dp_tunnel_mgr_create(struct drm_device *dev, int max_group_count)
 	}
 
 #ifdef CONFIG_DRM_DISPLAY_DP_TUNNEL_STATE_DEBUG
-	ref_tracker_dir_init(&mgr->ref_tracker, 16, "drm_dptun", "dptun");
+	ref_tracker_dir_init(&mgr->ref_tracker, 16, "drm_dptun");
 #endif
 
 	for (i = 0; i < max_group_count; i++) {

drivers/gpu/drm/i915/intel_runtime_pm.c

@@ -61,7 +61,7 @@ static void init_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm)
 {
 	if (!rpm->debug.class)
 		ref_tracker_dir_init(&rpm->debug, INTEL_REFTRACK_DEAD_COUNT,
-				     "intel_runtime_pm", dev_name(rpm->kdev));
+				     "intel_runtime_pm");
 }
 
 static intel_wakeref_t

drivers/gpu/drm/i915/intel_wakeref.c

@@ -115,7 +115,7 @@ void __intel_wakeref_init(struct intel_wakeref *wf,
 
 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
 	if (!wf->debug.class)
-		ref_tracker_dir_init(&wf->debug, INTEL_REFTRACK_DEAD_COUNT, "intel_wakeref", name);
+		ref_tracker_dir_init(&wf->debug, INTEL_REFTRACK_DEAD_COUNT, "intel_wakeref");
 #endif
 }
 

include/linux/ref_tracker.h

@@ -20,7 +20,6 @@ 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 */
-	char			name[32];
 #endif
 };
 
@@ -44,10 +43,21 @@ void ref_tracker_dir_symlink(struct ref_tracker_dir *dir, const char *fmt, ...)
 
 #endif /* CONFIG_DEBUG_FS */
 
+/**
+ * ref_tracker_dir_init - initialize a ref_tracker dir
+ * @dir: ref_tracker_dir to be initialized
+ * @quarantine_count: max number of entries to be tracked
+ * @class: pointer to static string that describes object type
+ *
+ * Initialize a ref_tracker_dir. If debugfs is configured, then a file
+ * will also be created for it under the top-level ref_tracker debugfs
+ * directory.
+ *
+ * Note that @class must point to a static string.
+ */
 static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
 					unsigned int quarantine_count,
-					const char *class,
+					const char *class)
-					const char *name)
 {
 	INIT_LIST_HEAD(&dir->list);
 	INIT_LIST_HEAD(&dir->quarantine);
@@ -57,7 +67,6 @@ 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;
-	strscpy(dir->name, name, sizeof(dir->name));
 	ref_tracker_dir_debugfs(dir);
 	stack_depot_init();
 }
@@ -82,8 +91,7 @@ int ref_tracker_free(struct ref_tracker_dir *dir,
 
 static inline void ref_tracker_dir_init(struct ref_tracker_dir *dir,
 					unsigned int quarantine_count,
-					const char *class,
+					const char *class)
-					const char *name)
 {
 }
 

lib/ref_tracker.c

@@ -155,7 +155,7 @@ __ref_tracker_dir_pr_ostream(struct ref_tracker_dir *dir,
 	stats = ref_tracker_get_stats(dir, display_limit);
 	if (IS_ERR(stats)) {
 		pr_ostream(s, "%s%s@%p: couldn't get stats, error %pe\n",
-			   s->prefix, dir->name, dir, stats);
+			   s->prefix, dir->class, dir, stats);
 		return;
 	}
 
@@ -166,14 +166,14 @@ __ref_tracker_dir_pr_ostream(struct ref_tracker_dir *dir,
 		if (sbuf && !stack_depot_snprint(stack, sbuf, STACK_BUF_SIZE, 4))
 			sbuf[0] = 0;
 		pr_ostream(s, "%s%s@%p has %d/%d users at\n%s\n", s->prefix,
-			   dir->name, dir, stats->stacks[i].count,
+			   dir->class, dir, stats->stacks[i].count,
 			   stats->total, sbuf);
 		skipped -= stats->stacks[i].count;
 	}
 
 	if (skipped)
 		pr_ostream(s, "%s%s@%p skipped reports about %d/%d users.\n",
-			   s->prefix, dir->name, dir, skipped, stats->total);
+			   s->prefix, dir->class, dir, skipped, stats->total);
 
 	kfree(sbuf);
 

lib/test_ref_tracker.c

@@ -64,7 +64,7 @@ static int __init test_ref_tracker_init(void)
 {
 	int i;
 
-	ref_tracker_dir_init(&ref_dir, 100, "selftest", "selftest");
+	ref_tracker_dir_init(&ref_dir, 100, "selftest");
 
 	timer_setup(&test_ref_tracker_timer, test_ref_tracker_timer_func, 0);
 	mod_timer(&test_ref_tracker_timer, jiffies + 1);

net/core/dev.c

@@ -11715,7 +11715,7 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
 
 	dev->priv_len = sizeof_priv;
 
-	ref_tracker_dir_init(&dev->refcnt_tracker, 128, "netdev", name);
+	ref_tracker_dir_init(&dev->refcnt_tracker, 128, "netdev");
 #ifdef CONFIG_PCPU_DEV_REFCNT
 	dev->pcpu_refcnt = alloc_percpu(int);
 	if (!dev->pcpu_refcnt)

net/core/net_namespace.c

@@ -403,8 +403,8 @@ static __net_init void preinit_net(struct net *net, struct user_namespace *user_
 {
 	refcount_set(&net->passive, 1);
 	refcount_set(&net->ns.count, 1);
-	ref_tracker_dir_init(&net->refcnt_tracker, 128, "net_refcnt", "net_refcnt");
+	ref_tracker_dir_init(&net->refcnt_tracker, 128, "net_refcnt");
-	ref_tracker_dir_init(&net->notrefcnt_tracker, 128, "net_notrefcnt", "net_notrefcnt");
+	ref_tracker_dir_init(&net->notrefcnt_tracker, 128, "net_notrefcnt");
 
 	get_random_bytes(&net->hash_mix, sizeof(u32));
 	net->dev_base_seq = 1;