Re: [PATCH] kcsan, compiler_types: avoid duplicate type issues in BPF Type Format

[Yonghong Song]

On 1/16/26 1:17 AM, Alan Maguire wrote:
> Enabling KCSAN is causing a large number of duplicate types
> in BTF for core kernel structs like task_struct [1].
> This is due to the definition in include/linux/compiler_types.h
>
> `#ifdef __SANITIZE_THREAD__
> ...
> `#define __data_racy volatile
> ..
> `#else
> ...
> `#define __data_racy
> ...
> `#endif
>
> Because some objects in the kernel are compiled without
> KCSAN flags (KCSAN_SANITIZE) we sometimes get the empty
> __data_racy annotation for objects; as a result we get multiple
> conflicting representations of the associated structs in DWARF,
> and these lead to multiple instances of core kernel types in
> BTF since they cannot be deduplicated due to the additional
> modifier in some instances.
>
> Moving the __data_racy definition under CONFIG_KCSAN
> avoids this problem, since the volatile modifier will
> be present for both KCSAN and KCSAN_SANITIZE objects
> in a CONFIG_KCSAN=y kernel.
>
> Fixes: 31f605a308e6 ("kcsan, compiler_types: Introduce __data_racy type qualifier")
> Reported-by: Nilay Shroff <nilay@xxxxxxxxxxxxx>
> Suggested-by: Marco Elver <elver@xxxxxxxxxx>
> Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>

Tested on gcc15 and llvm22 and all works okay. Also
the patch itself makes sense, so

Acked-by: Yonghong Song <yonghong.song@xxxxxxxxx>