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Subject: Re: [PATCH v3 3/6] staging: r8188eu: add error handling of rtw_read8
To:     "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
        Larry.Finger@lwfinger.net, phil@philpotter.co.uk,
        gregkh@linuxfoundation.org, straube.linux@gmail.com
Cc:     linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org
References: <cover.1629789580.git.paskripkin@gmail.com>
 <c59d5d850bf9aab208704182c83086609289cb9c.1629789580.git.paskripkin@gmail.com>
 <3591772.nrefL38gfN@localhost.localdomain>
From:   Pavel Skripkin <paskripkin@gmail.com>
Message-ID: <1f9ef1b3-8581-3261-0cfe-d5e9a8cf8483@gmail.com>
Date:   Thu, 26 Aug 2021 08:13:29 +0300
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On 8/26/21 2:45 AM, Fabio M. De Francesco wrote:
> On Tuesday, August 24, 2021 9:27:27 AM CEST Pavel Skripkin wrote:
>> _rtw_read8 function can fail in case of usb transfer failure. But
>> previous function prototype wasn't designed to return an error to
>> caller. It can cause a lot uninit value bugs all across the driver code,
>> since rtw_read8() returns local stack variable to caller.
>> 
>> Fix it by changing the prototype of this function. Now it returns an
>> int: 0 on success, negative error value on failure and callers should pass
>> the pointer to storage location for register value.
>> 
>> Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
> 
> Dear Pavel,
> 
> I have to inform you that building patch v3 3/6 with gcc (version 11.1.1 20210721
> [revision 076930b9690ac3564638636f6b13bbb6bc608aea] (SUSE Linux)), gives
> the following warning:
> 
> drivers/staging/r8188eu/os_dep/ioctl_linux.c:2258:13: warning: variable ‘error’ set but not used [-Wunused-but-set-variable]
>   2258 |         int error;
>        |             ^~~~~
> 
> I'm sorry, but I guess that for some reason previously I had only built v2 of your patch
> which had no warnings at all.
> 
> Unfortunately, introducing warnings is not allowed.
> 
> While we are at this, I can also confirm that GCC 11.1.1 _does_ _not_ emit the warning
> that has been reported by the kernel test robot.
> 

Yep, I see, thank you. v4 is on the way... I had a plan to send v4 
yesterday, but I've finally received r8188eu device.

I tried to connect it and test and.... driver didn't work :) So, I will 
try to figure out the problem with driver (or device) and will send v4.

Again, thank you for report :) My default gcc is too polite...


With regards,
Pavel Skripkin