tree:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git perf-wip
head:   03b560ccf75e145d2bdc374f3f6f670500a12c94
commit: 03b560ccf75e145d2bdc374f3f6f670500a12c94 [19/19] block: move direct_IO into our own read_iter handler
config: hexagon-buildonly-randconfig-r001-20211028 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 5db7568a6a1fcb408eb8988abdaff2a225a8eb72)
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/axboe/linux-block.git/commit/?id=03b560ccf75e145d2bdc374f3f6f670500a12c94
        git remote add axboe-block https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git
        git fetch --no-tags axboe-block perf-wip
        git checkout 03b560ccf75e145d2bdc374f3f6f670500a12c94
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=hexagon 

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

All errors (new ones prefixed by >>):

>> block/fops.c:584:6: error: variable 'ret' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
           if (iocb->ki_flags & IOCB_DIRECT) {
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
   block/fops.c:610:31: note: uninitialized use occurs here
           ret = filemap_read(iocb, to, ret);
                                        ^~~
   block/fops.c:584:2: note: remove the 'if' if its condition is always true
           if (iocb->ki_flags & IOCB_DIRECT) {
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   block/fops.c:572:13: note: initialize the variable 'ret' to silence this warning
           ssize_t ret;
                      ^
                       = 0
   1 error generated.


vim +584 block/fops.c

   564	
   565	static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
   566	{
   567		struct block_device *bdev = iocb->ki_filp->private_data;
   568		loff_t size = bdev->bd_nr_sectors << SECTOR_SHIFT;
   569		size_t count = iov_iter_count(to);
   570		loff_t pos = iocb->ki_pos;
   571		size_t shorted = 0;
   572		ssize_t ret;
   573	
   574		if (unlikely(pos + count > size)) {
   575			if (pos >= size)
   576				return 0;
   577			size -= pos;
   578			if (count > size) {
   579				shorted = count - size;
   580				iov_iter_truncate(to, size);
   581			}
   582		}
   583	
 > 584		if (iocb->ki_flags & IOCB_DIRECT) {
   585			struct address_space *mapping = iocb->ki_filp->f_mapping;
   586	
   587			if (iocb->ki_flags & IOCB_NOWAIT) {
   588				if (filemap_range_needs_writeback(mapping, iocb->ki_pos,
   589							iocb->ki_pos + count - 1))
   590					return -EAGAIN;
   591			} else {
   592				ret = filemap_write_and_wait_range(mapping,
   593							iocb->ki_pos,
   594						        iocb->ki_pos + count - 1);
   595				if (ret < 0)
   596					return ret;
   597			}
   598	
   599			file_accessed(iocb->ki_filp);
   600	
   601			ret = blkdev_direct_IO(iocb, to);
   602			if (ret >= 0) {
   603				iocb->ki_pos += ret;
   604				count -= ret;
   605			}
   606			if (ret < 0 || !count)
   607				return ret;
   608		}
   609	
   610		ret = filemap_read(iocb, to, ret);
   611	
   612		if (unlikely(shorted))
   613			iov_iter_reexpand(to, iov_iter_count(to) + shorted);
   614		return ret;
   615	}
   616	

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