Re: [PATCH bpf-next v2 0/2] bpf: Fix sleepable check for tracing prog

[Leon Hwang <leon.hwang@linux.dev>]

On 31/7/26 23:21, Andrii Nakryiko wrote:
> On Thu, Jul 30, 2026 at 10:20 PM Leon Hwang <leon.hwang@linux.dev> wrote:
>>
>> On 31/7/26 08:07, Andrii Nakryiko wrote:
>>> On Sat, Jul 25, 2026 at 6:27 AM Leon Hwang <leon.hwang@linux.dev> wrote:
>>>>
>>>> When CONFIG_FUNCTION_ERROR_INJECTION is disabled, a sleepable tracing prog
>>>> is allowed to attach to '__x64_'-alike prefix symbols.
>>>>
>>>> It is because the verifier does not verify whether the symbol is a kernel
>>>> function or a bpf prog. That said, a sleepable tracing prog is allowed to
>>>> attach to a bpf prog target whose name has '__x64_'-alike prefix.
>>>>
>>>> For example, a sleepable fentry prog attaches to a '__x64_sys_nop' XDP
>>>
>>> we do have addr, so we should be able to distinguish between attaching
>>> to kernel function vs BPF program, no?
>>
>>
>> Yes, we can distinguish a bpf prog from a kernel function by addr.
>>
>> I'd prefer passing 'tgt_prog' to btf_id_allow_sleepable() as a simple
>> change.
>>
> 
> I don't think there is a need for new tgt_prog argument, we can just
> check that supplied btf is not kernel/module BTF (see btf_is_kernel())
> 

Makes sense.

Will use btf_is_kernel().

Thanks,
Leon