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libbpf: Fix deduplication of typedef with base definitions

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When deduplicating definitions for a module, typedef defined in the base
are not removed. This is because the hash used for base types differs
from the one used in the deduplication logic in btf_dedup_struct_type.

This was introduced by the referenced commit when moving the typedef
deduplication logic handling from btf_dedup_ref_type to
btf_dedup_struct_type, as this also changed the hash logic
(btf_hash_common to btf_hash_typedef).

This also impacts other types referencing those typedef (e.g. const). In
my test, the BTF section size of the openvswitch module went from 31KB
to 45KB.

Fixes: 3781413465 ("libbpf: Fix BTF dedup to support recursive typedef definitions").
Signed-off-by: Antoine Tenart <atenart@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Alan Maguire <alan.maguire@oracle.com>
Reviewed-by: Alan Maguire <alan.maguire@oracle.com>
Link: https://lore.kernel.org/bpf/20260417083319.32716-1-atenart@kernel.org
This commit is contained in:
Antoine Tenart 2026-04-17 10:33:17 +02:00 committed by Andrii Nakryiko
parent a20f97791a
commit 0831b110eb
1 changed files with 3 additions and 1 deletions
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4
tools/lib/bpf/btf.c
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@ -4592,12 +4592,14 @@ static int btf_dedup_prep(struct btf_dedup *d)
case BTF_KIND_RESTRICT:
case BTF_KIND_PTR:
case BTF_KIND_FWD:
case BTF_KIND_TYPEDEF:
case BTF_KIND_FUNC:
case BTF_KIND_FLOAT:
case BTF_KIND_TYPE_TAG:
h = btf_hash_common(t);
break;
case BTF_KIND_TYPEDEF:
h = btf_hash_typedef(t);
break;
case BTF_KIND_INT:
case BTF_KIND_DECL_TAG:
h = btf_hash_int_decl_tag(t);