Re: [PATCH 1/2] [v2] bpf: hide unused bpf_patch_call_args

[Arnd Bergmann]

On Wed, May 24, 2023, at 05:05, Yonghong Song wrote:
> On 5/23/23 12:43 PM, Arnd Bergmann wrote:
>> From: Arnd Bergmann <arnd@xxxxxxxx>
>> 
>> This function has no callers and no declaration when CONFIG_BPF_JIT_ALWAYS_ON
>> is enabled:
>> 
>> kernel/bpf/core.c:2075:6: error: no previous prototype for 'bpf_patch_call_args' [-Werror=missing-prototypes]
>
> If CONFIG_BPF_JIT_ALWAYS_ON is enabled, the definition of
> bpf_patch_call_args should be invisible. Maybe I missed something.
> Could you list *ALL& bpf related config options in your setup
> so people can reproduce you above error messages?

Sorry, my mistake. I've reworded the changelog now to fix this:

| This function is only used when CONFIG_BPF_JIT_ALWAYS_ON is disabled,
| but CONFIG_BPF_SYSCALL is enabled. When both are turned off, the
| prototype is missing but the unused function is still compiled,
| as seen from this W=1 warning:
| 
| kernel/bpf/core.c:2075:6: error: no previous prototype for 'bpf_patch_call_args' [-Werror=missing-prototypes]
| 
| Add a matching #ifdef for the definition to leave it out.

If this makes sense now, I'll send out a v3.

      Arnd