Hi Florian, I love your patch! Perhaps something to improve: [auto build test WARNING on kselftest/next] [also build test WARNING on mptcp/export linus/master v5.14-rc6 next-20210816] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Florian-Westphal/mptcp-add-SOL_M... base: https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git next config: i386-randconfig-a012-20210816 (attached as .config) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 44d0a99a12ec7ead4d2f5ef649ba05b40f6d463d) 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/0day-ci/linux/commit/7eb1b6e289708ffa4da5aa98540a83a8b... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Florian-Westphal/mptcp-add-SOL_MPTCP-getsockopt-support/20210817-003412 git checkout 7eb1b6e289708ffa4da5aa98540a83a8b22bc452 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): default: ^~~~~~~ mptcp_sockopt.c:545:14: note: uninitialized use occurs here r = xaccept(fd); ^~ mptcp_sockopt.c:527:8: note: initialize the variable 'fd' to silence this warning int fd, r; ^ = 0 mptcp_sockopt.c:565:2: warning: variable 'fd' is used uninitialized whenever switch default is taken [-Wsometimes-uninitialized] default: ^~~~~~~ mptcp_sockopt.c:569:21: note: uninitialized use occurs here connect_one_server(fd); ^~ mptcp_sockopt.c:554:8: note: initialize the variable 'fd' to silence this warning int fd; ^ = 0 2 warnings generated. --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org