Re: [PATCH RFC bpf-next 2/2] selftests/bpf: Add LoongArch support for get_preempt_count()

On 2026/4/20 下午9:35, [email protected] wrote:
> Sashiko AI review found 1 potential issue(s):
> - [High] BPF programs including `bpf_experimental.h` will fail to compile on LoongArch due to a non-existent `thread_info` field in `struct task_struct`.
> --
> 
> commit 82453686fe5eacd9f219e2a050dc016b297cfc79
> Author: Tiezhu Yang <[email protected]>
> 
> selftests/bpf: Add LoongArch support for get_preempt_count()
> 
> This commit adds LoongArch support for get_preempt_count() in the BPF
> experimental helpers. It enables bpf_in_interrupt() and related macros to
> work properly on LoongArch systems.
> 
>> diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h
>> index e5c039bc44cb4..5847bbf12d240 100644
>> --- a/tools/testing/selftests/bpf/bpf_experimental.h
>> +++ b/tools/testing/selftests/bpf/bpf_experimental.h
>> @@ -507,6 +507,8 @@ static inline int get_preempt_count(void)
>>   	return bpf_get_lowcore()->preempt_count;
>>   #elif defined(bpf_target_riscv)
>>   	return bpf_get_current_task_btf()->thread_info.preempt_count;
>> +#elif defined(bpf_target_loongarch)
>> +	return bpf_get_current_task_btf()->thread_info.preempt_count;
> 
> Will this compile successfully on LoongArch?
> 
> Since LoongArch does not select CONFIG_THREAD_INFO_IN_TASK, struct
> thread_info is allocated on the kernel stack rather than being embedded
> within struct task_struct. Because of this, the generated BTF and vmlinux.h
> for LoongArch will not contain a thread_info field in task_struct.
> 
> Could this lead to a compiler error indicating that there is no member named
> thread_info in struct task_struct when building BPF selftests?

As mentioned in the cover letter, it needs to apply the kernel patch
"LoongArch: Implement CONFIG_THREAD_INFO_IN_TASK" [1] before testing.

[1] 
https://lore.kernel.org/loongarch/[email protected]/

Thanks,
Tiezhu