Re: [linux-next:master 3581/12910] arch/powerpc/kvm/../../../virt/kvm/vfio.c:89:7: error: attribute declaration must precede definition

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Aug 25, 2023 at 07:23:29PM +0800, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> head:   6269320850097903b30be8f07a5c61d9f7592393
> commit: c1cce6d079b875396c9a7c6838fc5b024758e540 [3581/12910] vfio: Compile vfio_group infrastructure optionally
> config: powerpc64-randconfig-r001-20230825 (https://download.01.org/0day-ci/archive/20230825/202308251949.5IiaV0sz-lkp@intel.com/config)
> compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07)
> reproduce: (https://download.01.org/0day-ci/archive/20230825/202308251949.5IiaV0sz-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/202308251949.5IiaV0sz-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
> >> arch/powerpc/kvm/../../../virt/kvm/vfio.c:89:7: error: attribute declaration must precede definition [-Werror,-Wignored-attributes]
>            fn = symbol_get(vfio_file_iommu_group);
>                 ^
>    include/linux/module.h:805:60: note: expanded from macro 'symbol_get'
>    #define symbol_get(x) ({ extern typeof(x) x __attribute__((weak,visibility("hidden"))); &(x); })
>                                                               ^
>    include/linux/vfio.h:294:35: note: previous definition is here
>    static inline struct iommu_group *vfio_file_iommu_group(struct file *file)
>                                      ^
> >> arch/powerpc/kvm/../../../virt/kvm/vfio.c:89:7: error: attribute declaration must precede definition [-Werror,-Wignored-attributes]
>            fn = symbol_get(vfio_file_iommu_group);
>                 ^
>    include/linux/module.h:805:65: note: expanded from macro 'symbol_get'

This VFIO code is fine..

>    #define symbol_get(x) ({ extern typeof(x) x __attribute__((weak,visibility("hidden"))); &(x); })
>                                                                    ^
>    include/linux/vfio.h:294:35: note: previous definition is here
>    static inline struct iommu_group *vfio_file_iommu_group(struct file *file)
>                                      ^
>    2 errors generated.

Clang is complaining about this line

Which is from:

commit 13150bc5416f45234c955e5bed91623d178c6117
Author: Ard Biesheuvel <ardb@kernel.org>
Date:   Tue Oct 27 16:11:32 2020 +0100

    module: use hidden visibility for weak symbol references
    
    Geert reports that commit be2881824ae9eb92 ("arm64/build: Assert for
    unwanted sections") results in build errors on arm64 for configurations
    that have CONFIG_MODULES disabled.

I assume some tweaking there or a clang change is needed

(BTW does clang actually work on power, I tried it a bit ago and it
didn't get very far)

Thanks,
Jason