On 10/23/23 3:00 PM, Dave Marchevsky wrote:
If a struct has a bpf_refcount field, the refcount controls lifetime of
the entire struct. Currently there's no usecase or support for multiple
bpf_refcount fields in a struct.
bpf_spin_lock and bpf_timer fields don't support multiples either, but
with better error behavior. Parsing BTF w/ a struct containing multiple
{bpf_spin_lock, bpf_timer} fields fails in btf_get_field_type, while
multiple bpf_refcount fields doesn't fail BTF parsing at all, instead
triggering a WARN_ON_ONCE in btf_parse_fields, with the verifier using
the last bpf_refcount field to actually do refcounting.
This patch changes bpf_refcount handling in btf_get_field_type to use
same error logic as bpf_spin_lock and bpf_timer. Since it's being used
3x and is boilerplatey, the logic is shoved into
field_mask_test_name_check_seen helper macro.
Signed-off-by: Dave Marchevsky <davemarchevsky@xxxxxx>
Fixes: d54730b50bae ("bpf: Introduce opaque bpf_refcount struct and add btf_record plumbing")
Acked-by: Yonghong Song <yonghong.song@xxxxxxxxx>
