Re: [song-md:md-next 25/29] drivers/md/raid1-10.c:117:25: error: casting from randomized structure pointer type 'struct block_device *' to 'struct md_rdev *'

[Yu Kuai <yukuai1@huaweicloud.com>]

Hi,

在 2023/06/14 20:32, kernel test robot 写道:
> tree:   git://git.kernel.org/pub/scm/linux/kernel/git/song/md.git md-next
> head:   460af1f9d9e62acce4a21f9bd00b5bcd5963bcd4
> commit: 8295efbe68c080047e98d9c0eb5cb933b238a8cb [25/29] md/raid1-10: factor out a helper to submit normal write
> config: arm-randconfig-r026-20230612 (https://download.01.org/0day-ci/archive/20230614/202306142042.fmjfmTF8-lkp@intel.com/config)
> compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
> reproduce (this is a W=1 build):
>          mkdir -p ~/bin
>          wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>          chmod +x ~/bin/make.cross
>          # install arm cross compiling tool for clang build
>          # apt-get install binutils-arm-linux-gnueabi
>          # https://git.kernel.org/pub/scm/linux/kernel/git/song/md.git/commit/?id=8295efbe68c080047e98d9c0eb5cb933b238a8cb
>          git remote add song-md git://git.kernel.org/pub/scm/linux/kernel/git/song/md.git
>          git fetch --no-tags song-md md-next
>          git checkout 8295efbe68c080047e98d9c0eb5cb933b238a8cb
>          # save the config file
>          mkdir build_dir && cp config build_dir/.config
>          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang ~/bin/make.cross W=1 O=build_dir ARCH=arm olddefconfig
>          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang ~/bin/make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash drivers/
> 
> 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/202306142042.fmjfmTF8-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
>     In file included from drivers/md/raid10.c:80:
>>> drivers/md/raid1-10.c:117:25: error: casting from randomized structure pointer type 'struct block_device *' to 'struct md_rdev *'
>       117 |         struct md_rdev *rdev = (struct md_rdev *)bio->bi_bdev;

I didn't hit this warning with W=1 in my local machine, so I guess this
might related to compiler. I'm using gcc (GCC) 12.2.1 and here is clang
version 17.0.0.

I'm planning to get rid of all these weird usage, which is used a lot in
raid, to borrow a field to store something else temporarily, but this
might take sometime.

Can someone help to confirm following change can prevent this warning?

struct md_rdev *rdev = (void *)bio->bi_bdev

Thanks,
Kuai

>           |                                ^
>     1 error generated.
> 
> 
> vim +117 drivers/md/raid1-10.c
> 
>     113	
>     114	
>     115	static inline void raid1_submit_write(struct bio *bio)
>     116	{
>   > 117		struct md_rdev *rdev = (struct md_rdev *)bio->bi_bdev;
>     118	
>     119		bio->bi_next = NULL;
>     120		bio_set_dev(bio, rdev->bdev);
>     121		if (test_bit(Faulty, &rdev->flags))
>     122			bio_io_error(bio);
>     123		else if (unlikely(bio_op(bio) ==  REQ_OP_DISCARD &&
>     124				  !bdev_max_discard_sectors(bio->bi_bdev)))
>     125			/* Just ignore it */
>     126			bio_endio(bio);
>     127		else
>     128			submit_bio_noacct(bio);
>     129	}
>     130	
>