Re: [PATCH HID 03/13] HID: bpf: implement HID-BPF through bpf_struct_ops

[kernel test robot]

Hi Benjamin,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 70ec81c2e2b4005465ad0d042e90b36087c36104]

url:    https://github.com/intel-lab-lkp/linux/commits/Benjamin-Tissoires/HID-rename-struct-hid_bpf_ops-into-hid_ops/20240528-212222
base:   70ec81c2e2b4005465ad0d042e90b36087c36104
patch link:    https://lore.kernel.org/r/20240528-hid_bpf_struct_ops-v1-3-8c6663df27d8%40kernel.org
patch subject: [PATCH HID 03/13] HID: bpf: implement HID-BPF through bpf_struct_ops
config: i386-buildonly-randconfig-002-20240531 (https://download.01.org/0day-ci/archive/20240531/202405312035.U1rZN04z-lkp@xxxxxxxxx/config)
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240531/202405312035.U1rZN04z-lkp@xxxxxxxxx/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405312035.U1rZN04z-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

   In file included from include/linux/bpf_verifier.h:7:0,
                    from drivers/hid/bpf/hid_bpf_struct_ops.c:10:
   drivers/hid/bpf/hid_bpf_struct_ops.c: In function 'hid_bpf_struct_ops_init':
>> include/linux/bpf.h:1844:50: warning: statement with no effect [-Wunused-value]
    #define register_bpf_struct_ops(st_ops, type) ({ (void *)(st_ops); 0; })
                                                     ^~~~~~~~~~~~~~~~
   drivers/hid/bpf/hid_bpf_struct_ops.c:244:9: note: in expansion of macro 'register_bpf_struct_ops'
     return register_bpf_struct_ops(&bpf_hid_bpf_ops, hid_bpf_ops);
            ^~~~~~~~~~~~~~~~~~~~~~~


vim +1844 include/linux/bpf.h

c196906d50e360d Hou Tao          2021-10-25  1834  
c196906d50e360d Hou Tao          2021-10-25  1835  int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
c196906d50e360d Hou Tao          2021-10-25  1836  			    union bpf_attr __user *uattr);
c196906d50e360d Hou Tao          2021-10-25  1837  #endif
f6be98d19985411 Kui-Feng Lee     2024-01-19  1838  int bpf_struct_ops_desc_init(struct bpf_struct_ops_desc *st_ops_desc,
f6be98d19985411 Kui-Feng Lee     2024-01-19  1839  			     struct btf *btf,
f6be98d19985411 Kui-Feng Lee     2024-01-19  1840  			     struct bpf_verifier_log *log);
1338b93346587a2 Kui-Feng Lee     2024-01-19  1841  void bpf_map_struct_ops_info_fill(struct bpf_map_info *info, struct bpf_map *map);
1611603537a4b88 Kui-Feng Lee     2024-02-08  1842  void bpf_struct_ops_desc_release(struct bpf_struct_ops_desc *st_ops_desc);
27ae7997a66174c Martin KaFai Lau 2020-01-08  1843  #else
f6be98d19985411 Kui-Feng Lee     2024-01-19 @1844  #define register_bpf_struct_ops(st_ops, type) ({ (void *)(st_ops); 0; })
85d33df357b6346 Martin KaFai Lau 2020-01-08  1845  static inline bool bpf_try_module_get(const void *data, struct module *owner)
85d33df357b6346 Martin KaFai Lau 2020-01-08  1846  {
85d33df357b6346 Martin KaFai Lau 2020-01-08  1847  	return try_module_get(owner);
85d33df357b6346 Martin KaFai Lau 2020-01-08  1848  }
85d33df357b6346 Martin KaFai Lau 2020-01-08  1849  static inline void bpf_module_put(const void *data, struct module *owner)
85d33df357b6346 Martin KaFai Lau 2020-01-08  1850  {
85d33df357b6346 Martin KaFai Lau 2020-01-08  1851  	module_put(owner);
85d33df357b6346 Martin KaFai Lau 2020-01-08  1852  }
85d33df357b6346 Martin KaFai Lau 2020-01-08  1853  static inline int bpf_struct_ops_map_sys_lookup_elem(struct bpf_map *map,
85d33df357b6346 Martin KaFai Lau 2020-01-08  1854  						     void *key,
85d33df357b6346 Martin KaFai Lau 2020-01-08  1855  						     void *value)
85d33df357b6346 Martin KaFai Lau 2020-01-08  1856  {
85d33df357b6346 Martin KaFai Lau 2020-01-08  1857  	return -EINVAL;
85d33df357b6346 Martin KaFai Lau 2020-01-08  1858  }
68b04864ca425d1 Kui-Feng Lee     2023-03-22  1859  static inline int bpf_struct_ops_link_create(union bpf_attr *attr)
68b04864ca425d1 Kui-Feng Lee     2023-03-22  1860  {
68b04864ca425d1 Kui-Feng Lee     2023-03-22  1861  	return -EOPNOTSUPP;
68b04864ca425d1 Kui-Feng Lee     2023-03-22  1862  }
1338b93346587a2 Kui-Feng Lee     2024-01-19  1863  static inline void bpf_map_struct_ops_info_fill(struct bpf_map_info *info, struct bpf_map *map)
1338b93346587a2 Kui-Feng Lee     2024-01-19  1864  {
1338b93346587a2 Kui-Feng Lee     2024-01-19  1865  }
68b04864ca425d1 Kui-Feng Lee     2023-03-22  1866  

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