[PATCH] usb: gadget: configfs: Fix set but not used variable warning

[PATCH] usb: gadget: configfs: Fix set but not used variable warning

[Daniel Scally]

Fix a -Wunused-but-set-variable warning in gadget_string_s_store()

Fixes: 15a7cf8caabe ("usb: gadget: configfs: Support arbitrary string descriptors")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
---
 drivers/usb/gadget/configfs.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c
index 06a0b73e0546..b9f1136aa0a2 100644
--- a/drivers/usb/gadget/configfs.c
+++ b/drivers/usb/gadget/configfs.c
@@ -821,13 +821,11 @@ static ssize_t gadget_string_s_store(struct config_item *item, const char *page,
 {
 	struct gadget_string *string = to_gadget_string(item);
 	int size = min(sizeof(string->string), len + 1);
-	int ret;
 
 	if (len > USB_MAX_STRING_LEN)
 		return -EINVAL;
 
-	ret = strscpy(string->string, page, size);
-	return len;
+	return strscpy(string->string, page, size);
 }
 CONFIGFS_ATTR(gadget_string_, s);
 
-- 
2.34.1

Re: [PATCH] usb: gadget: configfs: Fix set but not used variable warning

[Andy Shevchenko]

On Thu, Feb 09, 2023 at 09:43:59AM +0000, Daniel Scally wrote:
> Fix a -Wunused-but-set-variable warning in gadget_string_s_store()

A side comment below.

...

>  	if (len > USB_MAX_STRING_LEN)
>  		return -EINVAL;
>  
> -	ret = strscpy(string->string, page, size);
> -	return len;
> +	return strscpy(string->string, page, size);

Do you need above check with strscpy()? You may supply the maximum length
and negative error code from the strscpy() will indicate the cut.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] usb: gadget: configfs: Fix set but not used variable warning

[Dan Scally]

Hi Andy

On 10/02/2023 15:54, Andy Shevchenko wrote:
> On Thu, Feb 09, 2023 at 09:43:59AM +0000, Daniel Scally wrote:
>> Fix a -Wunused-but-set-variable warning in gadget_string_s_store()
> A side comment below.
>
> ...
>
>>   	if (len > USB_MAX_STRING_LEN)
>>   		return -EINVAL;
>>   
>> -	ret = strscpy(string->string, page, size);
>> -	return len;
>> +	return strscpy(string->string, page, size);
> Do you need above check with strscpy()? You may supply the maximum length
> and negative error code from the strscpy() will indicate the cut.
>
It would still copy the truncated string in that case though, correct? 
Seems cleaner to me to just fail and leave the string as-is, but I don't 
particularly mind either way.

Re: [PATCH] usb: gadget: configfs: Fix set but not used variable warning

[Andy Shevchenko]

On Fri, Feb 10, 2023 at 04:03:52PM +0000, Dan Scally wrote:
> On 10/02/2023 15:54, Andy Shevchenko wrote:
> > On Thu, Feb 09, 2023 at 09:43:59AM +0000, Daniel Scally wrote:
> > > Fix a -Wunused-but-set-variable warning in gadget_string_s_store()
> > A side comment below.

...

> > >   	if (len > USB_MAX_STRING_LEN)
> > >   		return -EINVAL;
> > > -	ret = strscpy(string->string, page, size);
> > > -	return len;
> > > +	return strscpy(string->string, page, size);
> > Do you need above check with strscpy()? You may supply the maximum length
> > and negative error code from the strscpy() will indicate the cut.
> > 
> It would still copy the truncated string in that case though, correct? Seems
> cleaner to me to just fail and leave the string as-is, but I don't
> particularly mind either way.

Good point. Yes, depending on the nature of the data we copy it (my proposal)
may or may not be a good idea.

-- 
With Best Regards,
Andy Shevchenko