Re: [PATCH v3] USB: gadget: Add ID numbers to configfs-gadget driver names

[Heikki Krogerus <heikki.krogerus@linux.intel.com>]

On Wed, Jan 11, 2023 at 01:51:05PM +0700, Chanh Nguyen wrote:
> It is unable to use configfs to attach more than one gadget. When
> attaching the second gadget, it always fails and the kernel message
> prints out:
> 
> Error: Driver 'configfs-gadget' is already registered, aborting...
> UDC core: g1: driver registration failed: -16
> 
> This commit fixes the problem by using the gadget name as a suffix
> to each configfs_gadget's driver name, thus making the names
> distinct.
> 
> Fixes: fc274c1e9973 ("USB: gadget: Add a new bus for gadgets")
> Signed-off-by: Chanh Nguyen <chanh@os.amperecomputing.com>

Tested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

Thanks!

> ---
> Changes in v3:
>   - Use the gadget name as a unique suffix instead     [Andrzej]
>   - Remove the driver.name allocation by template        [Chanh]
>   - Update commit message                                [Chanh]
> 
> Changes in v2:
>   - Replace scnprintf() by kasprintf() to simplify the code [CJ]
>   - Move the clean up code from gadgets_drop() to
>     gadget_info_attr_release()                        [Frank Li]
>   - Correct the resource free up in gadges_make()   [Alan Stern]
>   - Remove the unnecessary variable in gadgets_make()    [Chanh]
>   - Fixes minor grammar issue in commit message          [Chanh]
> ---
>  drivers/usb/gadget/configfs.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
> index 96121d1c8df4..0853536cbf2e 100644
> --- a/drivers/usb/gadget/configfs.c
> +++ b/drivers/usb/gadget/configfs.c
> @@ -393,6 +393,7 @@ static void gadget_info_attr_release(struct config_item *item)
>  	WARN_ON(!list_empty(&gi->string_list));
>  	WARN_ON(!list_empty(&gi->available_func));
>  	kfree(gi->composite.gadget_driver.function);
> +	kfree(gi->composite.gadget_driver.driver.name);
>  	kfree(gi);
>  }
>  
> @@ -1572,7 +1573,6 @@ static const struct usb_gadget_driver configfs_driver_template = {
>  	.max_speed	= USB_SPEED_SUPER_PLUS,
>  	.driver = {
>  		.owner          = THIS_MODULE,
> -		.name		= "configfs-gadget",
>  	},
>  	.match_existing_only = 1,
>  };
> @@ -1623,13 +1623,21 @@ static struct config_group *gadgets_make(
>  
>  	gi->composite.gadget_driver = configfs_driver_template;
>  
> +	gi->composite.gadget_driver.driver.name = kasprintf(GFP_KERNEL,
> +							    "configfs-gadget.%s", name);
> +	if (!gi->composite.gadget_driver.driver.name)
> +		goto err;
> +
>  	gi->composite.gadget_driver.function = kstrdup(name, GFP_KERNEL);
>  	gi->composite.name = gi->composite.gadget_driver.function;
>  
>  	if (!gi->composite.gadget_driver.function)
> -		goto err;
> +		goto out_free_driver_name;
>  
>  	return &gi->group;
> +
> +out_free_driver_name:
> +	kfree(gi->composite.gadget_driver.driver.name);
>  err:
>  	kfree(gi);
>  	return ERR_PTR(-ENOMEM);
> -- 
> 2.17.1

-- 
heikki