Messages in this thread | ![/](/images/icornerl.gif) | | 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 22:52:24 +0200 |
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On 6/30/23 9:48 PM, SeongJae Park wrote: > On Fri, 30 Jun 2023 16:53:38 +0200 Daniel Borkmann <daniel@iogearbox.net> wrote: >> 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? > > You're correct. It's not urgent for us, but I would prefer it to be merged > into all affected kernels as early as possible.
Ok, sounds good, bpf tree it is then.
>>> 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? > > Again, you're correct. This change is not really needed. I was interpreting > Kumar's suggestion merely into code without thinking about his real meaning, > sorry. I will restore this in the next spin.
Perfect, I think after your v3 respin it should be good to land.
Thanks, Daniel
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