[dm-devel] [device-mapper-dm:dm-5.19 126/130] drivers/md/dm.c:1471:2: warning: Value stored to 'num_bios' is never read [clang-analyzer-deadcode.DeadStores]

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git dm-5.19
head:   d245a9c2bd77a40dab2f3393c4a413820dd6004d
commit: eb4cbc43473c35198e18c9b7b82e7a26fa6e5401 [126/130] dm: optimize is_abnormal_io for normal rw IO
config: i386-randconfig-c001 (https://download.01.org/0day-ci/archive/20220324/202203242338.J9k787ls-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 0f6d9501cf49ce02937099350d08f20c4af86f3d)
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
         # https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?id=eb4cbc43473c35198e18c9b7b82e7a26fa6e5401
         git remote add device-mapper-dm https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git
         git fetch --no-tags device-mapper-dm dm-5.19
         git checkout eb4cbc43473c35198e18c9b7b82e7a26fa6e5401
         # save the config file to linux build tree
         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=i386 clang-analyzer

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <yujie.liu at intel.com>


clang-analyzer warnings: (new ones prefixed by >>)

 >> drivers/md/dm.c:1471:2: warning: Value stored to 'num_bios' is never read [clang-analyzer-deadcode.DeadStores]
            num_bios = 0;
            ^          ~

vim +/num_bios +1471 drivers/md/dm.c

568c73a355e0b8 Mike Snitzer 2019-01-18  1462
0519c71e8d461a Mike Snitzer 2018-03-26  1463  static bool __process_abnormal_io(struct clone_info *ci, struct dm_target *ti,
0519c71e8d461a Mike Snitzer 2018-03-26  1464  				  int *result)
0519c71e8d461a Mike Snitzer 2018-03-26  1465  {
eb4cbc43473c35 Mike Snitzer 2022-03-22  1466  	unsigned num_bios;
eb4cbc43473c35 Mike Snitzer 2022-03-22  1467
eb4cbc43473c35 Mike Snitzer 2022-03-22  1468  	if (!is_abnormal_io(ci->bio))
eb4cbc43473c35 Mike Snitzer 2022-03-22  1469  		return false;
0519c71e8d461a Mike Snitzer 2018-03-26  1470
eb4cbc43473c35 Mike Snitzer 2022-03-22 @1471  	num_bios = 0;
e6fc9f62ce6e41 Mike Snitzer 2022-02-17  1472  	switch (bio_op(ci->bio)) {
9679b5a7ec400f Mike Snitzer 2020-09-15  1473  	case REQ_OP_DISCARD:
9679b5a7ec400f Mike Snitzer 2020-09-15  1474  		num_bios = ti->num_discard_bios;
9679b5a7ec400f Mike Snitzer 2020-09-15  1475  		break;
9679b5a7ec400f Mike Snitzer 2020-09-15  1476  	case REQ_OP_SECURE_ERASE:
9679b5a7ec400f Mike Snitzer 2020-09-15  1477  		num_bios = ti->num_secure_erase_bios;
9679b5a7ec400f Mike Snitzer 2020-09-15  1478  		break;
9679b5a7ec400f Mike Snitzer 2020-09-15  1479  	case REQ_OP_WRITE_SAME:
9679b5a7ec400f Mike Snitzer 2020-09-15  1480  		num_bios = ti->num_write_same_bios;
9679b5a7ec400f Mike Snitzer 2020-09-15  1481  		break;
9679b5a7ec400f Mike Snitzer 2020-09-15  1482  	case REQ_OP_WRITE_ZEROES:
9679b5a7ec400f Mike Snitzer 2020-09-15  1483  		num_bios = ti->num_write_zeroes_bios;
9679b5a7ec400f Mike Snitzer 2020-09-15  1484  		break;
9679b5a7ec400f Mike Snitzer 2020-09-15  1485  	default:
0519c71e8d461a Mike Snitzer 2018-03-26  1486  		return false;
9679b5a7ec400f Mike Snitzer 2020-09-15  1487  	}

num_bios will be assigned in each case.

0519c71e8d461a Mike Snitzer 2018-03-26  1488
e6fc9f62ce6e41 Mike Snitzer 2022-02-17  1489  	/*
e6fc9f62ce6e41 Mike Snitzer 2022-02-17  1490  	 * Even though the device advertised support for this type of
e6fc9f62ce6e41 Mike Snitzer 2022-02-17  1491  	 * request, that does not mean every target supports it, and
e6fc9f62ce6e41 Mike Snitzer 2022-02-17  1492  	 * reconfiguration might also have changed that since the
e6fc9f62ce6e41 Mike Snitzer 2022-02-17  1493  	 * check was performed.
e6fc9f62ce6e41 Mike Snitzer 2022-02-17  1494  	 */
e6fc9f62ce6e41 Mike Snitzer 2022-02-17  1495  	if (!num_bios)
e6fc9f62ce6e41 Mike Snitzer 2022-02-17  1496  		*result = -EOPNOTSUPP;
e6fc9f62ce6e41 Mike Snitzer 2022-02-17  1497  	else {
e6fc9f62ce6e41 Mike Snitzer 2022-02-17  1498  		__send_changing_extent_only(ci, ti, num_bios);
e6fc9f62ce6e41 Mike Snitzer 2022-02-17  1499  		*result = 0;
e6fc9f62ce6e41 Mike Snitzer 2022-02-17  1500  	}
0519c71e8d461a Mike Snitzer 2018-03-26  1501  	return true;
0519c71e8d461a Mike Snitzer 2018-03-26  1502  }
0519c71e8d461a Mike Snitzer 2018-03-26  1503

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp