Re: [PATCH v3] fs/btrfs: Fix uninitialized variable

[kernel test robot]

Hi Khaled,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on kdave/for-next]
[also build test WARNING on v5.12-rc8 next-20210420]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Khaled-ROMDHANI/fs-btrfs-Fix-uninitialized-variable/20210420-231754
base:   https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next
config: arm-randconfig-r021-20210420 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project ca8eef7e3da8f750d7c7aa004fe426d1d34787ea)
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://github.com/0day-ci/linux/commit/c05b2a58c9ed11bd753f1e64695bd89da715fbaa
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Khaled-ROMDHANI/fs-btrfs-Fix-uninitialized-variable/20210420-231754
        git checkout c05b2a58c9ed11bd753f1e64695bd89da715fbaa
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=arm 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

>> fs/btrfs/zoned.c:146:2: warning: variable 'zone' is used uninitialized whenever switch default is taken [-Wsometimes-uninitialized]
           default:
           ^~~~~~~
   fs/btrfs/zoned.c:153:14: note: uninitialized use occurs here
           return (u32)zone;
                       ^~~~
   fs/btrfs/zoned.c:139:10: note: initialize the variable 'zone' to silence this warning
           u64 zone;
                   ^
                    = 0
   1 warning generated.


vim +/zone +146 fs/btrfs/zoned.c

   133	
   134	/*
   135	 * Get the first zone number of the superblock mirror
   136	 */
   137	static inline u32 sb_zone_number(int shift, int mirror)
   138	{
   139		u64 zone;
   140	
   141		ASSERT(mirror < BTRFS_SUPER_MIRROR_MAX);
   142		switch (mirror) {
   143		case 0: zone = 0; break;
   144		case 1: zone = 1ULL << (BTRFS_SB_LOG_FIRST_SHIFT - shift); break;
   145		case 2: zone = 1ULL << (BTRFS_SB_LOG_SECOND_SHIFT - shift); break;
 > 146		default:
   147			ASSERT(zone);
   148			break;
   149		}
   150	
   151		ASSERT(zone <= U32_MAX);
   152	
   153		return (u32)zone;
   154	}
   155	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

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