Hi Stanislav,

I love your patch! Yet something to improve:

[auto build test ERROR on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Stanislav-Fomichev/xdp-hints-via-kfuncs/20221115-110547
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20221115030210.3159213-7-sdf%40google.com
patch subject: [PATCH bpf-next 06/11] xdp: Carry over xdp metadata into skb context
config: parisc-randconfig-r006-20221115
compiler: hppa-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/5c7e4e60d13af8491563dd4d2ad5fc684420e540
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Stanislav-Fomichev/xdp-hints-via-kfuncs/20221115-110547
        git checkout 5c7e4e60d13af8491563dd4d2ad5fc684420e540
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=parisc SHELL=/bin/bash net/core/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   In file included from include/linux/netdevice.h:43,
                    from include/linux/if_vlan.h:10,
                    from include/linux/filter.h:20,
                    from net/core/xdp.c:9:
   include/net/xdp.h: In function 'xdp_metadata_export_to_skb':
   include/net/xdp.h:449:16: error: 'return' with a value, in function returning void [-Werror=return-type]
     449 |         return 0;
         |                ^
   include/net/xdp.h:447:13: note: declared here
     447 | static void xdp_metadata_export_to_skb(const struct bpf_prog *prog, struct bpf_patch *patch)
         |             ^~~~~~~~~~~~~~~~~~~~~~~~~~
   net/core/xdp.c: At top level:
   net/core/xdp.c:734:14: warning: no previous prototype for 'bpf_xdp_metadata_export_to_skb' [-Wmissing-prototypes]
     734 | noinline int bpf_xdp_metadata_export_to_skb(const struct xdp_md *ctx)
         |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   net/core/xdp.c:743:14: warning: no previous prototype for 'bpf_xdp_metadata_rx_timestamp_supported' [-Wmissing-prototypes]
     743 | noinline int bpf_xdp_metadata_rx_timestamp_supported(const struct xdp_md *ctx)
         |              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   net/core/xdp.c:751:10: warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
     751 | noinline const __u64 bpf_xdp_metadata_rx_timestamp(const struct xdp_md *ctx)
         |          ^~~~~
   net/core/xdp.c:751:22: warning: no previous prototype for 'bpf_xdp_metadata_rx_timestamp' [-Wmissing-prototypes]
     751 | noinline const __u64 bpf_xdp_metadata_rx_timestamp(const struct xdp_md *ctx)
         |                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> net/core/xdp.c:881:6: error: redefinition of 'xdp_metadata_export_to_skb'
     881 | void xdp_metadata_export_to_skb(const struct bpf_prog *prog, struct bpf_patch *patch)
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~
   include/net/xdp.h:447:13: note: previous definition of 'xdp_metadata_export_to_skb' with type 'void(const struct bpf_prog *, struct bpf_patch *)'
     447 | static void xdp_metadata_export_to_skb(const struct bpf_prog *prog, struct bpf_patch *patch)
         |             ^~~~~~~~~~~~~~~~~~~~~~~~~~
   include/net/xdp.h:447:13: warning: 'xdp_metadata_export_to_skb' defined but not used [-Wunused-function]
   cc1: some warnings being treated as errors


vim +/xdp_metadata_export_to_skb +881 net/core/xdp.c

   872	
   873	static int __init xdp_metadata_init(void)
   874	{
   875		return register_btf_kfunc_id_set(BPF_PROG_TYPE_XDP, &xdp_metadata_kfunc_set);
   876	}
   877	late_initcall(xdp_metadata_init);
   878	#else
   879	struct btf_id_set8 xdp_metadata_kfunc_ids = {};
   880	EXPORT_SYMBOL(xdp_metadata_kfunc_ids);
 > 881	void xdp_metadata_export_to_skb(const struct bpf_prog *prog, struct bpf_patch *patch)

-- 
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