USB: dwc3: fix memory leak with using debugfs_lookup()

When calling debugfs_lookup() the result must have dput() called on it,
otherwise the memory will leak over time.  To make things simpler, just
call debugfs_lookup_and_remove() instead which handles all of the logic
at once.

Note, the root dentry for the debugfs directory for the device needs to
be saved so we don't have to keep looking it up, which required a bit
more refactoring to properly create and remove it when needed.
Reported-by: Bruce Chen <bruce.chen@unisoc.com>
Reported-by: Cixi Geng <cixi.geng1@unisoc.com>
Tested-by: Cixi Geng <gengcixi@gmail.com>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/20230202152820.2409908-1-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc3/core.h

@@ -1117,6 +1117,7 @@ struct dwc3_scratchpad_array {
  *		     address.
  * @num_ep_resized: carries the current number endpoints which have had its tx
  *		    fifo resized.
+ * @debug_root: root debugfs directory for this device to put its files in.
  */
 struct dwc3 {
 	struct work_struct	drd_work;
@@ -1332,6 +1333,7 @@ struct dwc3 {
 	int			max_cfg_eps;
 	int			last_fifo_depth;
 	int			num_ep_resized;
+	struct dentry		*debug_root;
 };
 
 #define INCRX_BURST_MODE 0

drivers/usb/dwc3/debug.h

@@ -414,11 +414,14 @@ static inline const char *dwc3_gadget_generic_cmd_status_string(int status)
 
 #ifdef CONFIG_DEBUG_FS
 extern void dwc3_debugfs_create_endpoint_dir(struct dwc3_ep *dep);
+extern void dwc3_debugfs_remove_endpoint_dir(struct dwc3_ep *dep);
 extern void dwc3_debugfs_init(struct dwc3 *d);
 extern void dwc3_debugfs_exit(struct dwc3 *d);
 #else
 static inline void dwc3_debugfs_create_endpoint_dir(struct dwc3_ep *dep)
 {  }
+static inline void dwc3_debugfs_remove_endpoint_dir(struct dwc3_ep *dep)
+{  }
 static inline void dwc3_debugfs_init(struct dwc3 *d)
 {  }
 static inline void dwc3_debugfs_exit(struct dwc3 *d)

drivers/usb/dwc3/debugfs.c

@@ -873,27 +873,23 @@ static const struct dwc3_ep_file_map dwc3_ep_file_map[] = {
 	{ "GDBGEPINFO", &dwc3_ep_info_register_fops, },
 };
 
-static void dwc3_debugfs_create_endpoint_files(struct dwc3_ep *dep,
-		struct dentry *parent)
+void dwc3_debugfs_create_endpoint_dir(struct dwc3_ep *dep)
 {
+	struct dentry		*dir;
 	int			i;
 
+	dir = debugfs_create_dir(dep->name, dep->dwc->debug_root);
 	for (i = 0; i < ARRAY_SIZE(dwc3_ep_file_map); i++) {
 		const struct file_operations *fops = dwc3_ep_file_map[i].fops;
 		const char *name = dwc3_ep_file_map[i].name;
 
-		debugfs_create_file(name, 0444, parent, dep, fops);
+		debugfs_create_file(name, 0444, dir, dep, fops);
 	}
 }
 
-void dwc3_debugfs_create_endpoint_dir(struct dwc3_ep *dep)
+void dwc3_debugfs_remove_endpoint_dir(struct dwc3_ep *dep)
 {
-	struct dentry		*dir;
-	struct dentry		*root;
-
-	root = debugfs_lookup(dev_name(dep->dwc->dev), usb_debug_root);
-	dir = debugfs_create_dir(dep->name, root);
-	dwc3_debugfs_create_endpoint_files(dep, dir);
+	debugfs_lookup_and_remove(dep->name, dep->dwc->debug_root);
 }
 
 void dwc3_debugfs_init(struct dwc3 *dwc)
@@ -911,6 +907,7 @@ void dwc3_debugfs_init(struct dwc3 *dwc)
 	dwc->regset->base = dwc->regs - DWC3_GLOBALS_REGS_START;
 
 	root = debugfs_create_dir(dev_name(dwc->dev), usb_debug_root);
+	dwc->debug_root = root;
 	debugfs_create_regset32("regdump", 0444, root, dwc->regset);
 	debugfs_create_file("lsp_dump", 0644, root, dwc, &dwc3_lsp_fops);
 
@@ -929,6 +926,6 @@ void dwc3_debugfs_init(struct dwc3 *dwc)
 
 void dwc3_debugfs_exit(struct dwc3 *dwc)
 {
-	debugfs_remove(debugfs_lookup(dev_name(dwc->dev), usb_debug_root));
+	debugfs_lookup_and_remove(dev_name(dwc->dev), usb_debug_root);
 	kfree(dwc->regset);
 }

drivers/usb/dwc3/gadget.c

@@ -3194,9 +3194,7 @@ static void dwc3_gadget_free_endpoints(struct dwc3 *dwc)
 			list_del(&dep->endpoint.ep_list);
 		}
 
-		debugfs_remove_recursive(debugfs_lookup(dep->name,
-				debugfs_lookup(dev_name(dep->dwc->dev),
-					       usb_debug_root)));
+		dwc3_debugfs_remove_endpoint_dir(dep);
 		kfree(dep);
 	}
 }