Re: [jlayton:mgtime 4/5] fs/inode.c:73:15: error: '__section__' attribute only applies to functions, global variables, Objective-C methods, and Objective-C properties

[Nathan Chancellor <nathan@kernel.org>]

On Tue, May 28, 2024 at 01:22:40PM +0800, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux.git mgtime
> head:   05aa6b03b8c3451d4aac5fb47e9e99c6e00ee304
> commit: 05ca0fa7e195e028694f41de279dec33ada93d21 [4/5] fs: add infrastructure for multigrain timestamps
> config: x86_64-rhel-8.3-rust (https://download.01.org/0day-ci/archive/20240528/202405281321.aRVc7usN-lkp@intel.com/config)
> compiler: clang version 18.1.5 (https://github.com/llvm/llvm-project 617a15a9eac96088ae5e9134248d8236e34b91b1)
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240528/202405281321.aRVc7usN-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/202405281321.aRVc7usN-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
> >> fs/inode.c:73:15: error: '__section__' attribute only applies to functions, global variables, Objective-C methods, and Objective-C properties
>       73 | static struct __cacheline_aligned_in_smp ctime_floor_val ctime_floor;
>          |               ^

The message is slightly obtuse but this attribute shouldn't be splitting
the type, otherwise it is parsed as a type attribute.

  static struct ctime_floor_val ctime_floor __cacheline_aligned_in_smp;

or

  static __cacheline_aligned_in_smp struct ctime_floor_val ctime_floor;

should work.

>    include/linux/cache.h:60:36: note: expanded from macro '__cacheline_aligned_in_smp'
>       60 | #define __cacheline_aligned_in_smp __cacheline_aligned
>          |                                    ^
>    include/linux/cache.h:55:4: note: expanded from macro '__cacheline_aligned'
>       55 |                  __section__(".data..cacheline_aligned")))
>          |                  ^
>    fs/inode.c:73:15: warning: attribute declaration must precede definition [-Wignored-attributes]
>    include/linux/cache.h:60:36: note: expanded from macro '__cacheline_aligned_in_smp'
>       60 | #define __cacheline_aligned_in_smp __cacheline_aligned
>          |                                    ^
>    include/linux/cache.h:54:18: note: expanded from macro '__cacheline_aligned'
>       54 |   __attribute__((__aligned__(SMP_CACHE_BYTES),                  \
>          |                  ^
>    fs/inode.c:64:8: note: previous definition is here
>       64 | struct ctime_floor_val {
>          |        ^
>    1 warning and 1 error generated.
> 
> 
> vim +/__section__ +73 fs/inode.c
> 
>     62	
>     63	/* Floor value for all ctime stamps */
>     64	struct ctime_floor_val {
>     65		union {
>     66			struct {
>     67				ktime_t	coarse;
>     68				ktime_t	floor;
>     69			};
>     70			u128	full;
>     71		};
>     72	};
>   > 73	static struct __cacheline_aligned_in_smp ctime_floor_val ctime_floor;
>     74	
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
>