linux-kernel - Re: [PATCH] blk: avoid divide-by-zero with zero granularity

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Date:   Wed, 13 Jan 2021 02:42:51 +0800
From:   kernel test robot <lkp@...el.com>
To:     Li Feng <fengli@...rtx.com>, Jens Axboe <axboe@...nel.dk>,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     kbuild-all@...ts.01.org, lifeng1519@...il.com,
        Li Feng <fengli@...rtx.com>
Subject: Re: [PATCH] blk: avoid divide-by-zero with zero granularity

Hi Li,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on block/for-next]
[also build test ERROR on v5.11-rc3 next-20210112]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Li-Feng/blk-avoid-divide-by-zero-with-zero-granularity/20210112-233454
base:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-next
config: x86_64-randconfig-c002-20210112 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/796e67f6b22f94f155669688e5e08281621b3ee6
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Li-Feng/blk-avoid-divide-by-zero-with-zero-granularity/20210112-233454
        git checkout 796e67f6b22f94f155669688e5e08281621b3ee6
        # save the attached .config to linux build tree
        make W=1 ARCH=x86_64 

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

All errors (new ones prefixed by >>):

   In file included from include/linux/blk-cgroup.h:23,
                    from include/linux/writeback.h:14,
                    from include/linux/memcontrol.h:22,
                    from include/linux/swap.h:9,
                    from include/linux/shmem_fs.h:6,
                    from drivers/gpu/drm/i915/i915_drv.h:49,
                    from <command-line>:
   include/linux/blkdev.h: In function 'queue_limit_alignment_offset':
>> include/linux/blkdev.h:1492:2: error: ISO C90 forbids mixed declarations and code [-Werror=declaration-after-statement]
    1492 |  unsigned int alignment = sector_div(sector, granularity >> SECTOR_SHIFT)
         |  ^~~~~~~~
   cc1: all warnings being treated as errors


vim +1492 include/linux/blkdev.h

c72758f33784e5e2 Martin K. Petersen 2009-05-22  1484  
e03a72e13648ac62 Martin K. Petersen 2010-01-11  1485  static inline int queue_limit_alignment_offset(struct queue_limits *lim, sector_t sector)
81744ee44ab2845c Martin K. Petersen 2009-12-29  1486  {
81744ee44ab2845c Martin K. Petersen 2009-12-29  1487  	unsigned int granularity = max(lim->physical_block_size, lim->io_min);
796e67f6b22f94f1 Li Feng            2021-01-12  1488  	granularity = granularity >> SECTOR_SHIFT;
796e67f6b22f94f1 Li Feng            2021-01-12  1489  	if (!granularity)
796e67f6b22f94f1 Li Feng            2021-01-12  1490  		return 0;
796e67f6b22f94f1 Li Feng            2021-01-12  1491  
233bde21aa43516b Bart Van Assche    2018-03-14 @1492  	unsigned int alignment = sector_div(sector, granularity >> SECTOR_SHIFT)
233bde21aa43516b Bart Van Assche    2018-03-14  1493  		<< SECTOR_SHIFT;
81744ee44ab2845c Martin K. Petersen 2009-12-29  1494  
b8839b8c55f3fdd6 Mike Snitzer       2014-10-08  1495  	return (granularity + lim->alignment_offset - alignment) % granularity;
c72758f33784e5e2 Martin K. Petersen 2009-05-22  1496  }
c72758f33784e5e2 Martin K. Petersen 2009-05-22  1497  

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

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