Hi Michal,

url:    https://github.com/0day-ci/linux/commits/Michal-Rostecki/Add-roundrobin-raid1-read-policy/20210210-053511
base:    92bf22614b21a2706f4993b278017e437f7785b3
config: i386-randconfig-m021-20210209 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

New smatch warnings:
fs/btrfs/volumes.c:635 btrfs_check_mixed() error: uninitialized symbol 'prev_device'.

Old smatch warnings:
fs/btrfs/volumes.c:1264 open_fs_devices() error: we previously assumed 'latest_dev' could be null (see line 1252)

vim +/prev_device +635 fs/btrfs/volumes.c

bd7608b9a9bbf6 Michal Rostecki 2021-02-09  629  static bool btrfs_check_mixed(struct btrfs_fs_devices *fs_devices,
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  630  			      bool new_device_rotating)
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  631  {
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  632  	struct btrfs_device *device, *prev_device;
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  633  
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  634  	list_for_each_entry(device, &fs_devices->devices, dev_list) {
bd7608b9a9bbf6 Michal Rostecki 2021-02-09 @635  		if (prev_device == NULL &&
                                                                    ^^^^^^^^^^^^^^^^^^^
Uninitialized.

bd7608b9a9bbf6 Michal Rostecki 2021-02-09  636  		    device->rotating != new_device_rotating)
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  637  			return true;
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  638  		if (prev_device != NULL &&
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  639  		    (device->rotating != prev_device->rotating ||
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  640  		     device->rotating != new_device_rotating))
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  641  			return true;
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  642  
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  643  		prev_device = device;
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  644  	}
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  645  
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  646  	return false;
bd7608b9a9bbf6 Michal Rostecki 2021-02-09  647  }

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