Re: [kbuild-all] Re: net/bpf/test_run.c:154:14: warning: no previous prototype for 'bpf_fentry_test7'

[Rong Chen]

On 6/4/21 11:52 PM, Yonghong Song wrote:
> On 6/4/21 12:50 AM, kernel test robot wrote:
> > Hi Yonghong,
> >
> > FYI, the error/warning still remains.
> >
> > tree: 
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 
> > master
> > head:   f88cd3fb9df228e5ce4e13ec3dbad671ddb2146e
> > commit: d923021c2ce12acb50dc7086a1bf66eed82adf6a bpf: Add tests for 
> > PTR_TO_BTF_ID vs. null comparison
> > date:   11 months ago
> > config: x86_64-rhel (attached as .config)
> > compiler: gcc-6 (Ubuntu 6.4.0-17ubuntu1) 6.4.0 20180424
> > reproduce (this is a W=1 build):
> >          # 
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d923021c2ce12acb50dc7086a1bf66eed82adf6a
> >          git remote add linus 
> > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> >          git fetch --no-tags linus master
> >          git checkout d923021c2ce12acb50dc7086a1bf66eed82adf6a
> >          # save the attached .config to linux build tree
> >          make W=1 ARCH=x86_64
> >
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> >
> > All warnings (new ones prefixed by >>):
> >
> >     net/bpf/test_run.c:120:14: warning: no previous prototype for 
> > 'bpf_fentry_test1' [-Wmissing-prototypes]
> >      int noinline bpf_fentry_test1(int a)
> >                   ^~~~~~~~~~~~~~~~
> >     net/bpf/test_run.c:125:14: warning: no previous prototype for 
> > 'bpf_fentry_test2' [-Wmissing-prototypes]
> >      int noinline bpf_fentry_test2(int a, u64 b)
> >                   ^~~~~~~~~~~~~~~~
> >     net/bpf/test_run.c:130:14: warning: no previous prototype for 
> > 'bpf_fentry_test3' [-Wmissing-prototypes]
> >      int noinline bpf_fentry_test3(char a, int b, u64 c)
> >                   ^~~~~~~~~~~~~~~~
> >     net/bpf/test_run.c:135:14: warning: no previous prototype for 
> > 'bpf_fentry_test4' [-Wmissing-prototypes]
> >      int noinline bpf_fentry_test4(void *a, char b, int c, u64 d)
> >                   ^~~~~~~~~~~~~~~~
> >     net/bpf/test_run.c:140:14: warning: no previous prototype for 
> > 'bpf_fentry_test5' [-Wmissing-prototypes]
> >      int noinline bpf_fentry_test5(u64 a, void *b, short c, int d, 
> > u64 e)
> >                   ^~~~~~~~~~~~~~~~
> >     net/bpf/test_run.c:145:14: warning: no previous prototype for 
> > 'bpf_fentry_test6' [-Wmissing-prototypes]
> >      int noinline bpf_fentry_test6(u64 a, void *b, short c, int d, 
> > void *e, u64 f)
> >                   ^~~~~~~~~~~~~~~~
> > > > net/bpf/test_run.c:154:14: warning: no previous prototype for 
> > > > 'bpf_fentry_test7' [-Wmissing-prototypes]
> >      int noinline bpf_fentry_test7(struct bpf_fentry_test_t *arg)
> >                   ^~~~~~~~~~~~~~~~
> > > > net/bpf/test_run.c:159:14: warning: no previous prototype for 
> > > > 'bpf_fentry_test8' [-Wmissing-prototypes]
> >      int noinline bpf_fentry_test8(struct bpf_fentry_test_t *arg)
> >                   ^~~~~~~~~~~~~~~~
> >     net/bpf/test_run.c:164:14: warning: no previous prototype for 
> > 'bpf_modify_return_test' [-Wmissing-prototypes]
> >      int noinline bpf_modify_return_test(int a, int *b)
> >                   ^~~~~~~~~~~~~~~~~~~~~~
>
> I think this has been discussed earlier.
>
> In net/bpf/test_run.c, we have,
>
> __diag_push();
> __diag_ignore(GCC, 8, "-Wmissing-prototypes",
>               "Global functions as their definitions will be in 
> vmlinux BTF");
> int noinline bpf_fentry_test1(int a)
> {
>         return a + 1;
> }
> ...
>
> Unfortunately, the __diag_ignore macro only effective for gcc8 and later.
>
> So for gcc6, the above warning will be emitted. Is it possible for the 
> tool to check and ignore this error if the gcc version is less than 8?

Hi Yonghong,

Thanks for the advice, we'll ignore this error later.

Best Regards,
Rong Chen