Re: [PATCH bpf-next v3 1/4] bpftool: Set BPF_F_XDP_DEV_BOUND_ONLY flag non-destructively

["Toke Høiland-Jørgensen" <toke@redhat.com>]

Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:

> On Tue, Sep 1, 2026 at 1:47 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>>
>> When setting the XDP hints ifname, bpftool would set the
>> BPF_F_XDP_DEV_BOUND_ONLY without looking at the existing program flags,
>> overriding any other flag values. This was always a destructive action,
>> but after we change libbpf to carry the frags section flag in
>> prog_flags, this can impact bpftool loading of XDP frags programs.
>>
>> Change the flag setting to be non-destructive by OR'ing it with the
>> existing flags.
>>
>> Fixes: f46392ee3dec ("bpftool: Specify XDP Hints ifname when loading program")
>> Reviewed-by: Larysa Zaremba <larysa.zaremba@intel.com>
>> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
>> ---
>>  tools/bpf/bpftool/prog.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
>> index a9f730d407a9..8c2f9255b36d 100644
>> --- a/tools/bpf/bpftool/prog.c
>> +++ b/tools/bpf/bpftool/prog.c
>> @@ -1769,7 +1769,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
>>                 }
>>
>>                 if (prog_type == BPF_PROG_TYPE_XDP && xdpmeta_ifindex) {
>> -                       bpf_program__set_flags(pos, BPF_F_XDP_DEV_BOUND_ONLY);
>> +                       bpf_program__set_flags(pos, bpf_program__flags(pos) | BPF_F_XDP_DEV_BOUND_ONLY);
>
> maybe we should just add bpf_program__add_flags() and
> bpf_program__clear_flags() to make life a touch easier and code in
> selftests and bpftool a touch less verbose?

Sure, I can follow up with those. Also makes for a convenient feature
detection target for this change :)

-Toke