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

[Chanh Nguyen <chanh@amperemail.onmicrosoft.com>]

On 11/01/2023 16:46, Andrzej Pietrasiewicz wrote:
> Hello,
> 
> W dniu 11.01.2023 o 07:51, Chanh Nguyen pisze:
>> 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>
>>
>> ---
>> 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);
> 
> This line is 88 chars long, which means you're taking advantage of 
> checkpatch
> allowing 100 columns nowadays. That's absolutely fine. If you collapse 
> the above
> two lines into one, the combined length is exactly 100 chars, so you might
> just as well use a single line. In any case (collapsed or not) you can 
> add my
> 
> Reviewed-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
> 

Thanks Andrzej for the review.

Just found out the commit title is not totally correct.
It should be "usb: gadget: Append name as suffix to configfs-gadget 
driver names".

I wonder if these issues could be fixed when get merged or should I 
resend a v4 with that two lines collapsed and with the title adjust?

Thanks a lot,
- Chanh

>> +    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);
>