Re: [PATCH v3 bpf-next 1/2] bpf: add a ksym BPF iterator

[Yonghong Song <yhs@fb.com>]

On 7/5/22 9:19 PM, Alexei Starovoitov wrote:
> On Mon, Jul 4, 2022 at 6:55 AM Alan Maguire <alan.maguire@oracle.com> wrote:
>>   static inline int kallsyms_for_perf(void)
>>   {
>>   #ifdef CONFIG_PERF_EVENTS
>> @@ -885,6 +967,18 @@ const char *kdb_walk_kallsyms(loff_t *pos)
>>   static int __init kallsyms_init(void)
>>   {
>>          proc_create("kallsyms", 0444, NULL, &kallsyms_proc_ops);
>> +#if defined(CONFIG_BPF_SYSCALL)
>> +       {
>> +               int ret;
>> +
>> +               ksym_iter_reg_info.ctx_arg_info[0].btf_id = *btf_ksym_iter_id;
>> +               ret = bpf_iter_reg_target(&ksym_iter_reg_info);
>> +               if (ret) {
>> +                       pr_warn("Warning: could not register bpf ksym iterator: %d\n", ret);
>> +                       return ret;
>> +               }
>> +       }
>> +#endif
> 
> The ifdef-s inside the function body are not pretty.
> I feel the v2 version was cleaner.
> static void __init bpf_ksym_iter_register()
> were only missing late_initcall(bpf_ksym_iter_register);
> to make it single #ifdef CONFIG_BPF_SYSCALL for everything.
> wdyt?

Okay, a separate function is good too. Also agree with Alexei
that a separate init call bpf_ksym_iter_register() is needed
since we need late_initcall(...) instead of device_initcall(...)
to be consistent with other bpf_iter's.