Hi Nitesh, kernel test robot noticed the following build warnings: [auto build test WARNING on 53cdf865f90ba922a854c65ed05b519f9d728424] url: https://github.com/intel-lab-lkp/linux/commits/Nitesh-Shetty/block-Introduce-queue-limits-for-copy-offload-support/20230628-163126 base: 53cdf865f90ba922a854c65ed05b519f9d728424 patch link: https://lore.kernel.org/r/20230627183629.26571-10-nj.shetty%40samsung.com patch subject: [PATCH v13 9/9] null_blk: add support for copy offload config: i386-randconfig-i006-20230628 (https://download.01.org/0day-ci/archive/20230628/202306282001.ba1qWTf0-lkp@xxxxxxxxx/config) compiler: clang version 15.0.7 (https://github.com/llvm/llvm-project.git 8dfdcc7b7bf66834a761bd8de445840ef68e4d1a) reproduce: (https://download.01.org/0day-ci/archive/20230628/202306282001.ba1qWTf0-lkp@xxxxxxxxx/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <lkp@xxxxxxxxx> | Closes: https://lore.kernel.org/oe-kbuild-all/202306282001.ba1qWTf0-lkp@xxxxxxxxx/ All warnings (new ones prefixed by >>): >> drivers/block/null_blk/main.c:1295:2: warning: variable 'rem' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized] __rq_for_each_bio(bio, req) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/blk-mq.h:1012:6: note: expanded from macro '__rq_for_each_bio' if ((rq->bio)) \ ^~~~~~~~~ drivers/block/null_blk/main.c:1300:15: note: uninitialized use occurs here if (WARN_ON(!rem)) ^~~ include/asm-generic/bug.h:123:25: note: expanded from macro 'WARN_ON' int __ret_warn_on = !!(condition); \ ^~~~~~~~~ drivers/block/null_blk/main.c:1295:2: note: remove the 'if' if its condition is always true __rq_for_each_bio(bio, req) { ^ include/linux/blk-mq.h:1012:2: note: expanded from macro '__rq_for_each_bio' if ((rq->bio)) \ ^ drivers/block/null_blk/main.c:1287:12: note: initialize the variable 'rem' to silence this warning size_t rem, temp; ^ = 0 1 warning generated. vim +1295 drivers/block/null_blk/main.c 1281 1282 static inline int nullb_setup_copy_write(struct nullb *nullb, 1283 struct request *req, bool is_fua) 1284 { 1285 sector_t sector_in, sector_out; 1286 void *in, *out; 1287 size_t rem, temp; 1288 struct bio *bio; 1289 unsigned long offset_in, offset_out; 1290 struct nullb_page *t_page_in, *t_page_out; 1291 int ret = -EIO; 1292 1293 sector_out = blk_rq_pos(req); 1294 > 1295 __rq_for_each_bio(bio, req) { 1296 sector_in = bio->bi_iter.bi_sector; 1297 rem = bio->bi_iter.bi_size; 1298 } 1299 1300 if (WARN_ON(!rem)) 1301 return BLK_STS_NOTSUPP; 1302 1303 spin_lock_irq(&nullb->lock); 1304 while (rem > 0) { 1305 temp = min_t(size_t, nullb->dev->blocksize, rem); 1306 offset_in = (sector_in & SECTOR_MASK) << SECTOR_SHIFT; 1307 offset_out = (sector_out & SECTOR_MASK) << SECTOR_SHIFT; 1308 1309 if (null_cache_active(nullb) && !is_fua) 1310 null_make_cache_space(nullb, PAGE_SIZE); 1311 1312 t_page_in = null_lookup_page(nullb, sector_in, false, 1313 !null_cache_active(nullb)); 1314 if (!t_page_in) 1315 goto err; 1316 t_page_out = null_insert_page(nullb, sector_out, 1317 !null_cache_active(nullb) || is_fua); 1318 if (!t_page_out) 1319 goto err; 1320 1321 in = kmap_local_page(t_page_in->page); 1322 out = kmap_local_page(t_page_out->page); 1323 1324 memcpy(out + offset_out, in + offset_in, temp); 1325 kunmap_local(out); 1326 kunmap_local(in); 1327 __set_bit(sector_out & SECTOR_MASK, t_page_out->bitmap); 1328 1329 if (is_fua) 1330 null_free_sector(nullb, sector_out, true); 1331 1332 rem -= temp; 1333 sector_in += temp >> SECTOR_SHIFT; 1334 sector_out += temp >> SECTOR_SHIFT; 1335 } 1336 1337 ret = 0; 1338 err: 1339 spin_unlock_irq(&nullb->lock); 1340 return ret; 1341 } 1342 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
