Re: [PATCH bpf-next v1 3/3] selftests/bpf: Make sure TLD_DEFINE_KEY runs first

[Mykyta Yatsenko <mykyta.yatsenko5@gmail.com>]

Amery Hung <ameryhung@gmail.com> writes:

> Without specifying constructor priority of the hidden constructor
> function defined by TLD_DEFINE_KEY, __tld_create_key(..., dyn_data =
> false) may run after tld_get_data() called from other constructors.
> Threads calling tld_get_data() before __tld_create_key(..., dyn_data
> = false) will not allocate enough memory for all TLDs and later result
> in OOB access. Therefore, set it to the lowest value available to
> users. Note that lower means higher priority and 0-100 is reserved to
> the compiler.
>
> Signed-off-by: Amery Hung <ameryhung@gmail.com>
> ---
>  tools/testing/selftests/bpf/prog_tests/task_local_data.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/task_local_data.h b/tools/testing/selftests/bpf/prog_tests/task_local_data.h
> index 366a6739c086..e242c455ddae 100644
> --- a/tools/testing/selftests/bpf/prog_tests/task_local_data.h
> +++ b/tools/testing/selftests/bpf/prog_tests/task_local_data.h
> @@ -278,7 +278,7 @@ static tld_key_t __tld_create_key(const char *name, size_t size, bool dyn_data)
>  #define TLD_DEFINE_KEY(key, name, size)			\
>  tld_key_t key;						\
>  							\
> -__attribute__((constructor))				\
> +__attribute__((constructor(101)))			\
>  void __tld_define_key_##key(void)			\
>  {							\
>  	key = __tld_create_key(name, size, false);	\
> -- 
> 2.52.0
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>