Re: [PATCH v13 9/9] null_blk: add support for copy offload

kernel test robot
2023-06-28T12:12:10Z

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: hexagon-randconfig-r045-20230628 (https://download.01.org/0day-ci/archive/20230628/202306281909.TRNCf5eG-lkp@intel.com/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
reproduce: (https://download.01.org/0day-ci/archive/20230628/202306281909.TRNCf5eG-lkp@intel.com/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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202306281909.TRNCf5eG-lkp@intel.com/

All warnings (new ones prefixed by >>):

In file included from drivers/block/null_blk/main.c:12:
In file included from drivers/block/null_blk/null_blk.h:8:
In file included from include/linux/blkdev.h:9:
In file included from include/linux/blk_types.h:10:
In file included from include/linux/bvec.h:10:
In file included from include/linux/highmem.h:12:
In file included from include/linux/hardirq.h:11:
In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
In file included from include/asm-generic/hardirq.h:17:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:13:
In file included from arch/hexagon/include/asm/io.h:334:
include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
547 | val = __raw_readb(PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
560 | val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
| ~~~~~~~~~~ ^
include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu'
37 | #define __le16_to_cpu(x) ((__force __u16)(__le16)(x))
| ^
In file included from drivers/block/null_blk/main.c:12:
In file included from drivers/block/null_blk/null_blk.h:8:
In file included from include/linux/blkdev.h:9:
In file included from include/linux/blk_types.h:10:
In file included from include/linux/bvec.h:10:
In file included from include/linux/highmem.h:12:
In file included from include/linux/hardirq.h:11:
In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
In file included from include/asm-generic/hardirq.h:17:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:13:
In file included from arch/hexagon/include/asm/io.h:334:
include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
573 | val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
| ~~~~~~~~~~ ^
include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
35 | #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
| ^
In file included from drivers/block/null_blk/main.c:12:
In file included from drivers/block/null_blk/null_blk.h:8:
In file included from include/linux/blkdev.h:9:
In file included from include/linux/blk_types.h:10:
In file included from include/linux/bvec.h:10:
In file included from include/linux/highmem.h:12:
In file included from include/linux/hardirq.h:11:
In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
In file included from include/asm-generic/hardirq.h:17:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:13:
In file included from arch/hexagon/include/asm/io.h:334:
include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
584 | __raw_writeb(value, PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
594 | __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
604 | __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
>> drivers/block/null_blk/main.c:1295:2: warning: variable 'rem' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
1295 | __rq_for_each_bio(bio, req) {
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/blk-mq.h:1012:2: note: expanded from macro '__rq_for_each_bio'
1012 | if ((rq->bio)) \
| ^~~~~~~~~~~~~~
include/linux/compiler.h:55:28: note: expanded from macro 'if'
55 | #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:57:30: note: expanded from macro '__trace_if_var'
57 | #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/block/null_blk/main.c:1300:15: note: uninitialized use occurs here
1300 | if (WARN_ON(!rem))
| ^~~
include/asm-generic/bug.h:123:25: note: expanded from macro 'WARN_ON'
123 | int __ret_warn_on = !!(condition); \
| ^~~~~~~~~
include/linux/compiler.h:55:47: note: expanded from macro 'if'
55 | #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
| ^~~~
include/linux/compiler.h:57:52: note: expanded from macro '__trace_if_var'
57 | #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
| ^~~~
drivers/block/null_blk/main.c:1295:2: note: remove the 'if' if its condition is always true
1295 | __rq_for_each_bio(bio, req) {
| ^
include/linux/blk-mq.h:1012:2: note: expanded from macro '__rq_for_each_bio'
1012 | if ((rq->bio)) \
| ^
include/linux/compiler.h:55:23: note: expanded from macro 'if'
55 | #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
| ^
drivers/block/null_blk/main.c:1287:12: note: initialize the variable 'rem' to silence this warning
1287 | size_t rem, temp;
| ^
| = 0
7 warnings 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