bpf: Add missing btf_put to register_btf_id_dtor_kfuncs

We take the BTF reference before we register dtors and we need to put it back when it's done.

We probably won't se a problem with kernel BTF, but module BTF would stay loaded (because of the extra ref) even when its module is removed.

Cc Kumar Kartikeya Dwivedi <[email protected]>

Fixes 5ce937d613a4 ("bpf: Populate pairs of btf_id and destructor kfunc in btf")

Signed-off-by Jiri Olsa <[email protected]>

---

 kernel/bpf/btf.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

kernel/bpf/btf.c +2 -3

index f7dd8af06413..b7017cae6fd1 100644
@@ -7782,9 +7782,9 @@ int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_c
 
        sort(tab->dtors, tab->cnt, sizeof(tab->dtors[0]), btf_id_cmp_func, NULL);
 
-       return 0;
 end:
-       btf_free_dtor_kfunc_tab(btf);
+       if (ret)
+               btf_free_dtor_kfunc_tab(btf);
        btf_put(btf);
        return ret;
 }
--

2.39.0

Quoted 8 lines · Jiri Olsa

We take the BTF reference before we register dtors and we need to put it back when it's done.

We probably won't se a problem with kernel BTF, but module BTF would stay loaded (because of the extra ref) even when its module is removed.

Quoted 4 lines

Cc Kumar Kartikeya Dwivedi <[email protected]>

Fixes 5ce937d613a4 ("bpf: Populate pairs of btf_id and destructor kfunc in btf")

Signed-off-by Jiri Olsa <[email protected]>

---

Thanks for the fix.

Acked-by Kumar Kartikeya Dwivedi <[email protected]>