On 06/09/2023 12:17, Denys Zagorui wrote:
> This cast was made by purpose for older libbpf where the
> bpf_object_skeleton field is void * instead of const void *
> to eliminte a warning (as i understand
s/eliminte/eliminate/
> -Wincompatible-pointer-types-discards-qualifiers) but this
> cast introduces another warnging (-Wcast-qual) for libbpf
s/warnging/warning/
> where data field is const void *
>
> It makes sense for bpftool to be in sync with libbpf from
> kernel sources
>
> Signed-off-by: Denys Zagorui <dzagorui@xxxxxxxxx>
> ---
> tools/bpf/bpftool/gen.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
> index 2883660d6b67..04c47745b3ea 100644
> --- a/tools/bpf/bpftool/gen.c
> +++ b/tools/bpf/bpftool/gen.c
> @@ -1209,7 +1209,7 @@ static int do_skeleton(int argc, char **argv)
> codegen("\
> \n\
> \n\
> - s->data = (void *)%2$s__elf_bytes(&s->data_sz); \n\
> + s->data = %2$s__elf_bytes(&s->data_sz); \n\
> \n\
> obj->skeleton = s; \n\
> return 0; \n\
If I follow correctly, the cast was added in bpftool in a6cc6b34b93e
("bpftool: Provide a helper method for accessing skeleton's embedded ELF
data"), which mentions indeed:
The assignment to s->data is cast to void * to ensure no warning is
issued if compiled with a previous version of libbpf where the
bpf_object_skeleton field is void * instead of const void *
but in libbpf, s->data's type had already been changed since commit
08a6f22ef6f8 ("libbpf: Change bpf_object_skeleton data field to const
pointer"), part of libbpf 0.6, is this correct?
If this is the case then the commit makes sense to me, I think it's OK
to have a warning with libbpf < 1.0 if it helps suppressing one when
loading skeletons with the current version of the lib.
Thanks,
Quentin
