[PATCH v4] drivers/hid: Check result of debugfs_create_dir() and debugfs_create_file()

[PATCH v4] drivers/hid: Check result of debugfs_create_dir() and debugfs_create_file()

[Alexander Kuleshov]

The debugfs_create_dir() and debugfs_create_file() functions may return -errno
if an error occurs. This patch adds a couple of checks of the result of the
debufs_create_dir() and debugfs_create_file() functions execution in the
hid_debug_register() and othre places.

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
---
Changelog:

v4:

  * Syntax error fixed.

v3:

  * do not check hid_debug before the call of the hid_debug_init()
and hid_debug_exit() from v2.

v2:

  * add check for the result of the debugfs_create_file() calls
  * call hid_debug_init() and hid_debug_exit() only if hid_debug
  * add check for the hid_debug_root in the hid_debug_register()

 drivers/hid/hid-core.c  |  9 ++++++---
 drivers/hid/hid-debug.c | 34 +++++++++++++++++++++++++++++++++-
 2 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index e6fce23..fea2a88 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2599,8 +2599,10 @@ int hid_add_device(struct hid_device *hdev)
 	ret = device_add(&hdev->dev);
 	if (!ret)
 		hdev->status |= HID_STAT_ADDED;
-	else
-		hid_debug_unregister(hdev);
+	else {
+		if (hdev->debug)
+			hid_debug_unregister(hdev);
+	}
 
 	return ret;
 }
@@ -2644,7 +2646,8 @@ static void hid_remove_device(struct hid_device *hdev)
 {
 	if (hdev->status & HID_STAT_ADDED) {
 		device_del(&hdev->dev);
-		hid_debug_unregister(hdev);
+		if (hdev->debug)
+			hid_debug_unregister(hdev);
 		hdev->status &= ~HID_STAT_ADDED;
 	}
 	kfree(hdev->dev_rdesc);
diff --git a/drivers/hid/hid-debug.c b/drivers/hid/hid-debug.c
index 2886b64..12fe6b6 100644
--- a/drivers/hid/hid-debug.c
+++ b/drivers/hid/hid-debug.c
@@ -1222,12 +1222,41 @@ static const struct file_operations hid_debug_events_fops = {
 
 void hid_debug_register(struct hid_device *hdev, const char *name)
 {
+	if (!hid_debug_root)
+		goto debugfs_root_error;
+
 	hdev->debug_dir = debugfs_create_dir(name, hid_debug_root);
+
+	if (!hdev->debug_dir) {
+		printk(KERN_WARNING "Could not create '%s' debugfs directory\n",
+			name);
+		return;
+	}
+
 	hdev->debug_rdesc = debugfs_create_file("rdesc", 0400,
 			hdev->debug_dir, hdev, &hid_debug_rdesc_fops);
+	if (!hdev->debug_rdesc) {
+		printk(KERN_WARNING "Could not create rdesc debugfs file\n");
+		goto error;
+	}
+
 	hdev->debug_events = debugfs_create_file("events", 0400,
 			hdev->debug_dir, hdev, &hid_debug_events_fops);
+	if (!hdev->debug_events) {
+		printk(KERN_WARNING "Could not create events debugfs file\n");
+		goto error;
+	}
+
 	hdev->debug = 1;
+
+	return;
+
+error:
+	debugfs_remove_recursive(hdev->debug_dir);
+	return;
+
+debugfs_root_error:
+	return;
 }
 
 void hid_debug_unregister(struct hid_device *hdev)
@@ -1242,10 +1271,13 @@ void hid_debug_unregister(struct hid_device *hdev)
 void hid_debug_init(void)
 {
 	hid_debug_root = debugfs_create_dir("hid", NULL);
+	if (!hid_debug_root)
+		printk(KERN_WARNING "Could not create root 'hid' debugfs directory\n");
 }
 
 void hid_debug_exit(void)
 {
-	debugfs_remove_recursive(hid_debug_root);
+	if (hid_debug_root)
+		debugfs_remove_recursive(hid_debug_root);
 }
 
-- 
2.5.0

Re: [PATCH v4] drivers/hid: Check result of debugfs_create_dir() and debugfs_create_file()

[Jiri Kosina]

On Fri, 4 Sep 2015, Alexander Kuleshov wrote:

> The debugfs_create_dir() and debugfs_create_file() functions may return -errno
> if an error occurs. This patch adds a couple of checks of the result of the
> debufs_create_dir() and debugfs_create_file() functions execution in the
> hid_debug_register() and othre places.
> 
> Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
> ---
> Changelog:
> 
> v4:
> 
>   * Syntax error fixed.
> 
> v3:
> 
>   * do not check hid_debug before the call of the hid_debug_init()
> and hid_debug_exit() from v2.
> 
> v2:
> 
>   * add check for the result of the debugfs_create_file() calls
>   * call hid_debug_init() and hid_debug_exit() only if hid_debug
>   * add check for the hid_debug_root in the hid_debug_register()
> 
>  drivers/hid/hid-core.c  |  9 ++++++---
>  drivers/hid/hid-debug.c | 34 +++++++++++++++++++++++++++++++++-
>  2 files changed, 39 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index e6fce23..fea2a88 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -2599,8 +2599,10 @@ int hid_add_device(struct hid_device *hdev)
>  	ret = device_add(&hdev->dev);
>  	if (!ret)
>  		hdev->status |= HID_STAT_ADDED;
> -	else
> -		hid_debug_unregister(hdev);
> +	else {
> +		if (hdev->debug)
> +			hid_debug_unregister(hdev);
> +	}
>  
>  	return ret;
>  }
> @@ -2644,7 +2646,8 @@ static void hid_remove_device(struct hid_device *hdev)
>  {
>  	if (hdev->status & HID_STAT_ADDED) {
>  		device_del(&hdev->dev);
> -		hid_debug_unregister(hdev);
> +		if (hdev->debug)
> +			hid_debug_unregister(hdev);

As we are sprinkling these checks around, and hid_debug_unregister() is a 
slow path anyway, I think I'll just rearrange the code that 
hid_debug_unregister() actually accepts NULL pointer.

Applied, thanks for the cleanup.

-- 
Jiri Kosina
SUSE Labs