Messages in this thread | | | Date | Wed, 6 Jul 2022 08:23:18 +0800 | From | kernel test robot <> | Subject | [kbusch:alignment-fixes 3/3] block/bio.c:1229:6: warning: variable 'i' is used uninitialized whenever 'if' condition is true |
| |
tree: https://git.kernel.org/pub/scm/linux/kernel/git/kbusch/linux.git alignment-fixes head: 9d1ebc4c688471ccd3bffa5e6b08a82a71431f7b commit: 9d1ebc4c688471ccd3bffa5e6b08a82a71431f7b [3/3] block: fix leaking page ref on truncated direct io config: x86_64-randconfig-a012 (https://download.01.org/0day-ci/archive/20220706/202207060806.4qoJVWlL-lkp@intel.com/config) compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 142aca7741d5b06207e87bf4880fbe308c8d6823) 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/kbusch/linux.git/commit/?id=9d1ebc4c688471ccd3bffa5e6b08a82a71431f7b git remote add kbusch https://git.kernel.org/pub/scm/linux/kernel/git/kbusch/linux.git git fetch --no-tags kbusch alignment-fixes git checkout 9d1ebc4c688471ccd3bffa5e6b08a82a71431f7b # 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=x86_64 SHELL=/bin/bash
If you fix the issue, kindly add following tag where applicable Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
>> block/bio.c:1229:6: warning: variable 'i' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized] if (unlikely(size <= 0)) { ^~~~~~~~~~~~~~~~~~~ include/linux/compiler.h:78:22: note: expanded from macro 'unlikely' # define unlikely(x) __builtin_expect(!!(x), 0) ^~~~~~~~~~~~~~~~~~~~~~~~~~ block/bio.c:1251:9: note: uninitialized use occurs here while (i < nr_pages) ^ block/bio.c:1229:2: note: remove the 'if' if its condition is always false if (unlikely(size <= 0)) { ^~~~~~~~~~~~~~~~~~~~~~~~~~ block/bio.c:1202:17: note: initialize the variable 'i' to silence this warning unsigned len, i; ^ = 0 1 warning generated.
vim +1229 block/bio.c
1184 1185 /** 1186 * __bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio 1187 * @bio: bio to add pages to 1188 * @iter: iov iterator describing the region to be mapped 1189 * 1190 * Pins pages from *iter and appends them to @bio's bvec array. The 1191 * pages will have to be released using put_page() when done. 1192 * For multi-segment *iter, this function only adds pages from the 1193 * next non-empty segment of the iov iterator. 1194 */ 1195 static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) 1196 { 1197 unsigned short nr_pages = bio->bi_max_vecs - bio->bi_vcnt; 1198 unsigned short entries_left = bio->bi_max_vecs - bio->bi_vcnt; 1199 struct bio_vec *bv = bio->bi_io_vec + bio->bi_vcnt; 1200 struct page **pages = (struct page **)bv; 1201 ssize_t size, left; 1202 unsigned len, i; 1203 size_t offset; 1204 int ret = 0; 1205 1206 /* 1207 * Move page array up in the allocated memory for the bio vecs as far as 1208 * possible so that we can start filling biovecs from the beginning 1209 * without overwriting the temporary page array. 1210 */ 1211 BUILD_BUG_ON(PAGE_PTRS_PER_BVEC < 2); 1212 pages += entries_left * (PAGE_PTRS_PER_BVEC - 1); 1213 1214 /* 1215 * Each segment in the iov is required to be a block size multiple. 1216 * However, we may not be able to get the entire segment if it spans 1217 * more pages than bi_max_vecs allows, so we have to ALIGN_DOWN the 1218 * result to ensure the bio's total size is correct. The remainder of 1219 * the iov data will be picked up in the next bio iteration. 1220 */ 1221 size = iov_iter_get_pages(iter, pages, UINT_MAX - bio->bi_iter.bi_size, 1222 nr_pages, &offset); 1223 if (size > 0) { 1224 nr_pages = DIV_ROUND_UP(offset + size, PAGE_SIZE); 1225 size = ALIGN_DOWN(size, bdev_logical_block_size(bio->bi_bdev)); 1226 } else 1227 nr_pages = 0; 1228 > 1229 if (unlikely(size <= 0)) { 1230 ret = size ? size : -EFAULT; 1231 goto out; 1232 } 1233 1234 for (left = size, i = 0; left > 0; left -= len, i++) { 1235 struct page *page = pages[i]; 1236 1237 len = min_t(size_t, PAGE_SIZE - offset, left); 1238 if (bio_op(bio) == REQ_OP_ZONE_APPEND) { 1239 ret = bio_iov_add_zone_append_page(bio, page, len, 1240 offset); 1241 if (ret) 1242 break; 1243 } else 1244 bio_iov_add_page(bio, page, len, offset); 1245 1246 offset = 0; 1247 } 1248 1249 iov_iter_advance(iter, size - left); 1250 out: 1251 while (i < nr_pages) 1252 put_page(pages[i++]); 1253 1254 return ret; 1255 } 1256
-- 0-DAY CI Kernel Test Service https://01.org/lkp
| |