tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c:54:1: warning: no previous prototype for 'bpf_testmod_test_btf_type_tag_percpu_1'

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   148341f0a2f53b5e8808d093333d85170586a15d
commit: 50c6b8a9aea2b8dc6c4ffb0cc502b94f7f57a0dc selftests/bpf: Add a test for btf_type_tag "percpu"
date:   1 year, 1 month ago
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=50c6b8a9aea2b8dc6c4ffb0cc502b94f7f57a0dc
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 50c6b8a9aea2b8dc6c4ffb0cc502b94f7f57a0dc
        make O=/tmp/kselftest headers
        make O=/tmp/kselftest -C tools/testing/selftests

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304041254.hj58GxCB-lkp@intel.com/

All warnings (new ones prefixed by >>):

   tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c:23:1: warning: no previous prototype for 'bpf_testmod_test_mod_kfunc' [-Wmissing-prototypes]
      23 | bpf_testmod_test_mod_kfunc(int i)
         | ^~~~~~~~~~~~~~~~~~~~~~~~~~
   tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c:41:1: warning: no previous prototype for 'bpf_testmod_test_btf_type_tag_user_1' [-Wmissing-prototypes]
      41 | bpf_testmod_test_btf_type_tag_user_1(struct bpf_testmod_btf_type_tag_1 __user *arg) {
         | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c:49:1: warning: no previous prototype for 'bpf_testmod_test_btf_type_tag_user_2' [-Wmissing-prototypes]
      49 | bpf_testmod_test_btf_type_tag_user_2(struct bpf_testmod_btf_type_tag_2 *arg) {
         | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c:54:1: warning: no previous prototype for 'bpf_testmod_test_btf_type_tag_percpu_1' [-Wmissing-prototypes]
      54 | bpf_testmod_test_btf_type_tag_percpu_1(struct bpf_testmod_btf_type_tag_1 __percpu *arg) {
         | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c:59:1: warning: no previous prototype for 'bpf_testmod_test_btf_type_tag_percpu_2' [-Wmissing-prototypes]
      59 | bpf_testmod_test_btf_type_tag_percpu_2(struct bpf_testmod_btf_type_tag_3 *arg) {
         | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c:63:14: warning: no previous prototype for 'bpf_testmod_loop_test' [-Wmissing-prototypes]
      63 | noinline int bpf_testmod_loop_test(int n)
         |              ^~~~~~~~~~~~~~~~~~~~~
   tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c:75:30: warning: no previous prototype for 'bpf_testmod_return_ptr' [-Wmissing-prototypes]
      75 | __weak noinline struct file *bpf_testmod_return_ptr(int arg)
         |                              ^~~~~~~~~~~~~~~~~~~~~~
   tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c:92:1: warning: no previous prototype for 'bpf_testmod_test_read' [-Wmissing-prototypes]
      92 | bpf_testmod_test_read(struct file *file, struct kobject *kobj,
         | ^~~~~~~~~~~~~~~~~~~~~
   tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c:128:1: warning: no previous prototype for 'bpf_testmod_test_write' [-Wmissing-prototypes]
     128 | bpf_testmod_test_write(struct file *file, struct kobject *kobj,
         | ^~~~~~~~~~~~~~~~~~~~~~
   tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.o: warning: objtool: bpf_testmod_return_ptr()+0x15: unreachable instruction


vim +/bpf_testmod_test_btf_type_tag_percpu_1 +54 tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c

    21	
    22	noinline void
  > 23	bpf_testmod_test_mod_kfunc(int i)
    24	{
    25		*(int *)this_cpu_ptr(&bpf_testmod_ksym_percpu) = i;
    26	}
    27	
    28	struct bpf_testmod_btf_type_tag_1 {
    29		int a;
    30	};
    31	
    32	struct bpf_testmod_btf_type_tag_2 {
    33		struct bpf_testmod_btf_type_tag_1 __user *p;
    34	};
    35	
    36	struct bpf_testmod_btf_type_tag_3 {
    37		struct bpf_testmod_btf_type_tag_1 __percpu *p;
    38	};
    39	
    40	noinline int
  > 41	bpf_testmod_test_btf_type_tag_user_1(struct bpf_testmod_btf_type_tag_1 __user *arg) {
    42		BTF_TYPE_EMIT(func_proto_typedef);
    43		BTF_TYPE_EMIT(func_proto_typedef_nested1);
    44		BTF_TYPE_EMIT(func_proto_typedef_nested2);
    45		return arg->a;
    46	}
    47	
    48	noinline int
    49	bpf_testmod_test_btf_type_tag_user_2(struct bpf_testmod_btf_type_tag_2 *arg) {
    50		return arg->p->a;
    51	}
    52	
    53	noinline int
  > 54	bpf_testmod_test_btf_type_tag_percpu_1(struct bpf_testmod_btf_type_tag_1 __percpu *arg) {
    55		return arg->a;
    56	}
    57	
    58	noinline int
  > 59	bpf_testmod_test_btf_type_tag_percpu_2(struct bpf_testmod_btf_type_tag_3 *arg) {
    60		return arg->p->a;
    61	}
    62	

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