Messages in this thread | | | Subject | Re: [PATCH v2] btf: warn but return no error for NULL btf from __register_btf_kfunc_id_set() | From | Daniel Borkmann <> | Date | Fri, 30 Jun 2023 16:53:38 +0200 |
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On 6/28/23 6:46 PM, SeongJae Park wrote: > __register_btf_kfunc_id_set() assumes .BTF to be part of the module's > .ko file if CONFIG_DEBUG_INFO_BTF is enabled. If that's not the case, > the function prints an error message and return an error. As a result, > such modules cannot be loaded. > > However, the section could be stripped out during a build process. It > would be better to let the modules loaded, because their basic > functionalities have no problem[1], though the BTF functionalities will > not be supported. Make the function to lower the level of the message > from error to warn, and return no error. > > [1] https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion/ > > Reported-by: Alexander Egorenkov <Alexander.Egorenkov@ibm.com> > Link: https://lore.kernel.org/bpf/87y228q66f.fsf@oc8242746057.ibm.com/ > Suggested-by: Kumar Kartikeya Dwivedi <memxor@gmail.com> > Link: https://lore.kernel.org/bpf/20220219082037.ow2kbq5brktf4f2u@apollo.legion/ > Fixes: c446fdacb10d ("bpf: fix register_btf_kfunc_id_set for !CONFIG_DEBUG_INFO_BTF") > Cc: <stable@vger.kernel.org> # 5.18.x > Signed-off-by: SeongJae Park <sj@kernel.org> > Acked-by: Jiri Olsa <jolsa@kernel.org>
I presume this one is targeted at bpf (rather than bpf-next) tree, right?
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c > index 6b682b8e4b50..d683f034996f 100644 > --- a/kernel/bpf/btf.c > +++ b/kernel/bpf/btf.c > @@ -7848,14 +7848,10 @@ static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook, > > btf = btf_get_module_btf(kset->owner); > if (!btf) { > - if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) { > - pr_err("missing vmlinux BTF, cannot register kfuncs\n"); > - return -ENOENT; > - }
Why the above one needs to be changed? Do you also run into this case? vmlinux BTF should be built-in in this case. I understand it's rather the one below for BTF + modules instead, no?
> - if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) { > - pr_err("missing module BTF, cannot register kfuncs\n"); > - return -ENOENT; > - } > + if (!kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF)) > + pr_warn("missing vmlinux BTF, cannot register kfuncs\n"); > + if (kset->owner && IS_ENABLED(CONFIG_DEBUG_INFO_BTF_MODULES)) > + pr_warn("missing module BTF, cannot register kfuncs\n"); > return 0; > } > if (IS_ERR(btf)) >
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