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Date:   Fri, 28 Oct 2022 11:13:15 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Cixi Geng <gengcixi@...il.com>
Cc:     Thinh.Nguyen@...opsys.com, bruce.chen@...soc.com,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: dwc3: Fix dentry leak in dwc3_gadget_free_endpoints

On Fri, Oct 28, 2022 at 04:49:19PM +0800, Cixi Geng wrote:
> From: Bruce Chen <bruce.chen@...soc.com>
> 
> When using debugfs_remove_recursive leaks a dentry with
> a hotplug stress test, the phone runs out of memory.
> 
> Thus fix the issue by using the newly created debugfs_lookup_and_remove().
> 
> Signed-off-by: Bruce Chen <bruce.chen@...soc.com>
> Signed-off-by: Cixi Geng <cixi.geng1@...soc.com>
> ---
>  drivers/usb/dwc3/core.h    | 1 +
>  drivers/usb/dwc3/debugfs.c | 3 ++-
>  drivers/usb/dwc3/gadget.c  | 4 +---
>  3 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 8f9959ba9fd4..ba3ecaa7f06c 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -1261,6 +1261,7 @@ struct dwc3 {
>  	u8			num_eps;
>  
>  	struct dwc3_hwparams	hwparams;
> +	struct dentry		*root;

You forgot to document this new variable.

And name it a bit better?

>  	struct debugfs_regset32	*regset;
>  
>  	u32			dbg_lsp_select;
> diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
> index f2b7675c7f62..b9af4a81f51d 100644
> --- a/drivers/usb/dwc3/debugfs.c
> +++ b/drivers/usb/dwc3/debugfs.c
> @@ -911,6 +911,7 @@ 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->root = root;
>  	debugfs_create_regset32("regdump", 0444, root, dwc->regset);
>  	debugfs_create_file("lsp_dump", 0644, root, dwc, &dwc3_lsp_fops);
>  
> @@ -929,6 +930,6 @@ 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_remove(dwc->root);
>  	kfree(dwc->regset);
>  }
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 079cd333632e..6d6c188fcbea 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -3172,9 +3172,7 @@ 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)));
> +		debugfs_lookup_and_remove(dep->name, dwc->root);
>  		kfree(dep);
>  	}
>  }
> -- 
> 2.34.1
> 

I don't think this is the full fix.

Below is a patch that I've had in a tree that I need to push out (along
with the other 33 debugfs_lookup patches) that should resolve this for
this driver in a more complete way.

Can you try this version instead?

thanks,

greg k-h

---------------------


>From 49b893792579af1bea46c5004759cb35475c4fca Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Date: Fri, 2 Sep 2022 16:41:39 +0200
Subject: [PATCH 06/34] USB: dwc3: debugfs_lookup() fix

Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/usb/dwc3/core.h    |  2 ++
 drivers/usb/dwc3/debug.h   |  3 +++
 drivers/usb/dwc3/debugfs.c | 19 ++++++++-----------
 drivers/usb/dwc3/gadget.c  |  4 +---
 4 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 8f9959ba9fd4..582ebd9cf9c2 100644
--- a/drivers/usb/dwc3/core.h
+++ b/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
diff --git a/drivers/usb/dwc3/debug.h b/drivers/usb/dwc3/debug.h
index 48b44b88dc25..8bb2c9e3b9ac 100644
--- a/drivers/usb/dwc3/debug.h
+++ b/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)
diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
index f2b7675c7f62..850df0e6bcab 100644
--- a/drivers/usb/dwc3/debugfs.c
+++ b/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);
 }
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 079cd333632e..404bb7ee61a8 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -3172,9 +3172,7 @@ 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);
 	}
 }
-- 
2.38.1

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