Re: [alobakin:bitops 3/7] block/elevator.c:222:9: sparse: sparse: cast from restricted req_flags_t

[Alexander Lobakin]

From: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Date: Mon, 20 Jun 2022 17:18:40 +0200

> On Mon, Jun 20, 2022 at 4:48 PM Alexander Lobakin
> <alexandr.lobakin@xxxxxxxxx> wrote:
> >
> > From: kernel test robot <lkp@xxxxxxxxx>
> > Date: Sun, 19 Jun 2022 17:20:05 +0800
> >
> > Also, could someone please help me with this? I don't get what went
> > wrong with sparse, it's not even some new code, just moving old
> > stuff.
> >
> > > tree:   https://github.com/alobakin/linux bitops
> > > head:   9bd39b17ce49d350eed93a031e0da6389067013e
> > > commit: 521611f961a7dda92eefa26e1afd3914c06af64e [3/7] bitops: unify non-atomic bitops prototypes across architectures
> > > config: mips-randconfig-s031-20220619 (https://download.01.org/0day-ci/archive/20220619/202206191726.wq70mbMK-lkp@xxxxxxxxx/config)
> > > compiler: mips64el-linux-gcc (GCC) 11.3.0
> > > reproduce:
> > >         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> > >         chmod +x ~/bin/make.cross
> > >         # apt-get install sparse
> > >         # sparse version: v0.6.4-30-g92122700-dirty
> > >         # https://github.com/alobakin/linux/commit/521611f961a7dda92eefa26e1afd3914c06af64e
> > >         git remote add alobakin https://github.com/alobakin/linux
> > >         git fetch --no-tags alobakin bitops
> > >         git checkout 521611f961a7dda92eefa26e1afd3914c06af64e
> > >         # save the config file
> > >         mkdir build_dir && cp config build_dir/.config
> > >         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=mips SHELL=/bin/bash
> > >
> > > If you fix the issue, kindly add following tag where applicable
> > > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > >
> > >
> > > sparse warnings: (new ones prefixed by >>)
> > >    command-line: note: in included file:
> > >    builtin:1:9: sparse: sparse: preprocessor token __ATOMIC_ACQUIRE redefined
> > >    builtin:0:0: sparse: this was the original definition
> > >    builtin:1:9: sparse: sparse: preprocessor token __ATOMIC_SEQ_CST redefined
> > >    builtin:0:0: sparse: this was the original definition
> > >    builtin:1:9: sparse: sparse: preprocessor token __ATOMIC_ACQ_REL redefined
> > >    builtin:0:0: sparse: this was the original definition
> > >    builtin:1:9: sparse: sparse: preprocessor token __ATOMIC_RELEASE redefined
> > >    builtin:0:0: sparse: this was the original definition
> > >    block/elevator.c: note: in included file (through include/linux/bitops.h, include/linux/kernel.h):
> > >    include/asm-generic/bitops/generic-non-atomic.h:29:9: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:30:9: sparse: sparse: unreplaced symbol 'p'
> > >    include/asm-generic/bitops/generic-non-atomic.h:32:10: sparse: sparse: unreplaced symbol 'p'
> > >    include/asm-generic/bitops/generic-non-atomic.h:32:16: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:27:1: sparse: sparse: unreplaced symbol 'return'
> > >    include/asm-generic/bitops/generic-non-atomic.h:38:9: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:39:9: sparse: sparse: unreplaced symbol 'p'
> > >    include/asm-generic/bitops/generic-non-atomic.h:41:10: sparse: sparse: unreplaced symbol 'p'
> > >    include/asm-generic/bitops/generic-non-atomic.h:41:16: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:36:1: sparse: sparse: unreplaced symbol 'return'
> > >    include/asm-generic/bitops/generic-non-atomic.h:56:9: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:57:9: sparse: sparse: unreplaced symbol 'p'
> > >    include/asm-generic/bitops/generic-non-atomic.h:59:10: sparse: sparse: unreplaced symbol 'p'
> > >    include/asm-generic/bitops/generic-non-atomic.h:59:15: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:54:1: sparse: sparse: unreplaced symbol 'return'
> > >    include/asm-generic/bitops/generic-non-atomic.h:74:9: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:75:9: sparse: sparse: unreplaced symbol 'p'
> > >    include/asm-generic/bitops/generic-non-atomic.h:76:9: sparse: sparse: unreplaced symbol 'old'
> > >    include/asm-generic/bitops/generic-non-atomic.h:78:10: sparse: sparse: unreplaced symbol 'p'
> > >    include/asm-generic/bitops/generic-non-atomic.h:78:14: sparse: sparse: unreplaced symbol 'old'
> > >    include/asm-generic/bitops/generic-non-atomic.h:78:20: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:79:17: sparse: sparse: unreplaced symbol 'old'
> > >    include/asm-generic/bitops/generic-non-atomic.h:79:23: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:79:9: sparse: sparse: unreplaced symbol 'return'
> > >    include/asm-generic/bitops/generic-non-atomic.h:72:1: sparse: sparse: unreplaced symbol 'return'
> > >    include/asm-generic/bitops/generic-non-atomic.h:94:9: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:95:9: sparse: sparse: unreplaced symbol 'p'
> > >    include/asm-generic/bitops/generic-non-atomic.h:96:9: sparse: sparse: unreplaced symbol 'old'
> > >    include/asm-generic/bitops/generic-non-atomic.h:98:10: sparse: sparse: unreplaced symbol 'p'
> > >    include/asm-generic/bitops/generic-non-atomic.h:98:14: sparse: sparse: unreplaced symbol 'old'
> > >    include/asm-generic/bitops/generic-non-atomic.h:98:21: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:99:17: sparse: sparse: unreplaced symbol 'old'
> > >    include/asm-generic/bitops/generic-non-atomic.h:99:23: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:99:9: sparse: sparse: unreplaced symbol 'return'
> > >    include/asm-generic/bitops/generic-non-atomic.h:92:1: sparse: sparse: unreplaced symbol 'return'
> > >    include/asm-generic/bitops/generic-non-atomic.h:106:9: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:107:9: sparse: sparse: unreplaced symbol 'p'
> > >    include/asm-generic/bitops/generic-non-atomic.h:108:9: sparse: sparse: unreplaced symbol 'old'
> > >    include/asm-generic/bitops/generic-non-atomic.h:110:10: sparse: sparse: unreplaced symbol 'p'
> > >    include/asm-generic/bitops/generic-non-atomic.h:110:14: sparse: sparse: unreplaced symbol 'old'
> > >    include/asm-generic/bitops/generic-non-atomic.h:110:20: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:111:17: sparse: sparse: unreplaced symbol 'old'
> > >    include/asm-generic/bitops/generic-non-atomic.h:111:23: sparse: sparse: unreplaced symbol 'mask'
> > >    include/asm-generic/bitops/generic-non-atomic.h:111:9: sparse: sparse: unreplaced symbol 'return'
> > >    include/asm-generic/bitops/generic-non-atomic.h:104:1: sparse: sparse: unreplaced symbol 'return'
> > >    include/asm-generic/bitops/generic-non-atomic.h:127:9: sparse: sparse: unreplaced symbol 'return'
> > >    include/asm-generic/bitops/generic-non-atomic.h:120:1: sparse: sparse: unreplaced symbol 'return'
> > > >> block/elevator.c:222:9: sparse: sparse: cast from restricted req_flags_t
> > >
> > > vim +222 block/elevator.c
> > >
> > > 9817064b68fef7 Jens Axboe        2006-07-28  217
> > > 70b3ea056f3074 Jens Axboe        2016-12-07  218  void elv_rqhash_add(struct request_queue *q, struct request *rq)
> > > 9817064b68fef7 Jens Axboe        2006-07-28  219  {
> > > b374d18a4bfce7 Jens Axboe        2008-10-31  220      struct elevator_queue *e = q->elevator;
> > > 9817064b68fef7 Jens Axboe        2006-07-28  221
> > > 9817064b68fef7 Jens Axboe        2006-07-28 @222      BUG_ON(ELV_ON_HASH(rq));
> > > 242d98f077ac0a Sasha Levin       2012-12-17  223      hash_add(e->hash, &rq->hash, rq_hash_key(rq));
> > > e806402130c9c4 Christoph Hellwig 2016-10-20  224      rq->rq_flags |= RQF_HASHED;
> > > 9817064b68fef7 Jens Axboe        2006-07-28  225  }
> > > bd166ef183c263 Jens Axboe        2017-01-17  226  EXPORT_SYMBOL_GPL(elv_rqhash_add);
> > > 9817064b68fef7 Jens Axboe        2006-07-28  227
> 
> It looks like a false positive for _your_ case, but if you want to fix
> here is the background.
> 
> The sparse has an ability to control custom types that should never
> set bits outside of the limited range. For this the special annotation
> is given, i.e. __bitwise. Since the culprit type is defined that way
> it means the pure integer (signed or unsigned) that comes with pure
> definition can't be used in a safe way. To solve this each of such
> definitions should be converted to the very same type (req_flags_t).
> See serial core where some UART flags are defined in a similar way and
> how code copes with that.

Ah, I haven't looked at the req_flags_t definition and didn't know
it uses bitwise annotation. So it's a local blk layer problem (not
casting from/to bitwise), not a generic header issue. Thanks for
the hint!

> 
> -- 
> With Best Regards,
> Andy Shevchenko

Thanks,
Olek