linux-kernel - Re: [char-misc:char-misc-linus 3/3] drivers/misc/cardreader/rtsx_usb.c:639:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true

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Date:   Fri, 1 Jul 2022 08:48:11 -0600
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        kernel test robot <lkp@...el.com>
Cc:     llvm@...ts.linux.dev, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org,
        Shuah Khan <skhan@...uxfoundation.org>
Subject: Re: [char-misc:char-misc-linus 3/3]
 drivers/misc/cardreader/rtsx_usb.c:639:6: warning: variable 'ret' is used
 uninitialized whenever 'if' condition is true

On 7/1/22 2:59 AM, Greg Kroah-Hartman wrote:
> On Fri, Jul 01, 2022 at 04:49:50PM +0800, kernel test robot wrote:
>> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git char-misc-linus
>> head:   3776c78559853fd151be7c41e369fd076fb679d5
>> commit: 3776c78559853fd151be7c41e369fd076fb679d5 [3/3] misc: rtsx_usb: use separate command and response buffers
>> config: arm-buildonly-randconfig-r006-20220629 (https://download.01.org/0day-ci/archive/20220701/202207011658.rHJFVLWA-lkp@intel.com/config)
>> compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project a9119143a2d1f4d0d0bc1fe0d819e5351b4e0deb)
>> reproduce (this is a W=1 build):
>>          wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>>          chmod +x ~/bin/make.cross
>>          # install arm cross compiling tool for clang build
>>          # apt-get install binutils-arm-linux-gnueabi
>>          # https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git/commit/?id=3776c78559853fd151be7c41e369fd076fb679d5
>>          git remote add char-misc https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
>>          git fetch --no-tags char-misc char-misc-linus
>>          git checkout 3776c78559853fd151be7c41e369fd076fb679d5
>>          # save the config file
>>          mkdir build_dir && cp config build_dir/.config
>>          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash drivers/misc/cardreader/
>>
>> If you fix the issue, kindly add following tag where applicable
>> Reported-by: kernel test robot <lkp@...el.com>
>>
>> All warnings (new ones prefixed by >>):
>>
>>>> drivers/misc/cardreader/rtsx_usb.c:639:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
>>             if (!ucr->rsp_buf)
>>                 ^~~~~~~~~~~~~
>>     drivers/misc/cardreader/rtsx_usb.c:678:9: note: uninitialized use occurs here
>>             return ret;
>>                    ^~~
>>     drivers/misc/cardreader/rtsx_usb.c:639:2: note: remove the 'if' if its condition is always false
>>             if (!ucr->rsp_buf)
>>             ^~~~~~~~~~~~~~~~~~
>>     drivers/misc/cardreader/rtsx_usb.c:622:9: note: initialize the variable 'ret' to silence this warning
>>             int ret;
>>                    ^
>>                     = 0
>>     1 warning generated.
> 
> Odd, gcc doesn't show this for me.  Shuah, can you send a follow-on
> patch to fix this?  The warning does look correct.
> 

gcc didn't complain when I compiled either. I will send a follow-on patch.

thanks,
-- Shuah