Hi WingMan, FYI, the error/warning still remains. tree: git://git.ti.com/ti-linux-kernel/ti-linux-kernel.git ti-rt-linux-5.10.y head: ac3657d2050406e974383b1490184f42a06b73cc commit: b98f7ec080e0de442e0be84994ec8d26bdc39eeb [6650/6833] net: socket: Forward extra timestamp of received skb to user space config: alpha-randconfig-r023-20210817 (attached as .config) compiler: alpha-linux-gcc (GCC) 11.2.0 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 git remote add ti git://git.ti.com/ti-linux-kernel/ti-linux-kernel.git git fetch --no-tags ti ti-rt-linux-5.10.y git checkout b98f7ec080e0de442e0be84994ec8d26bdc39eeb # save the attached .config to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=alpha SHELL=/bin/bash If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): In file included from include/net/cls_cgroup.h:14, from net/socket.c:95: include/net/sock.h: In function 'sock_recv_redundant_info': include/net/sock.h:2525:43: error: 'SCM_REDUNDANT' undeclared (first use in this function) 2525 | put_cmsg(msg, SOL_SOCKET, SCM_REDUNDANT, sizeof(*sred), sred); | ^~~~~~~~~~~~~ include/net/sock.h:2525:43: note: each undeclared identifier is reported only once for each function it appears in net/socket.c: In function '__sock_recv_redinfo_timestamp': 861 | SCM_RED_TIMESTAMPING, sizeof(tss), &tss); | ^~~~~~~~~~~~~~~~~~~~ vim +/SCM_RED_TIMESTAMPING +861 net/socket.c 845 846 void __sock_recv_redinfo_timestamp(struct msghdr *msg, struct sock *sk, 847 struct sk_buff *skb) 848 { 849 struct scm_timestamping_internal tss; 850 int empty = 1; 851 struct skb_shared_hwtstamps *red_shhwtstamps = 852 skb_redinfo_hwtstamps(skb); 853 854 if (red_shhwtstamps && 855 (sk->sk_tsflags & SOF_TIMESTAMPING_RAW_HARDWARE) && 856 ktime_to_timespec64_cond(red_shhwtstamps->hwtstamp, tss.ts + 2)) 857 empty = 0; 858 859 if (!empty) 860 put_cmsg(msg, SOL_SOCKET, 862 } 863 EXPORT_SYMBOL_GPL(__sock_recv_redinfo_timestamp); 864 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org