Hi Loic, I love your patch! Perhaps something to improve: [auto build test WARNING on net-next/master] url: https://github.com/0day-ci/linux/commits/Loic-Poulain/net-Add-a-WWAN-subs... base: https://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git 34bb975126419e86bc3b95e200dc41de6c6ca69c config: m68k-allmodconfig (attached as .config) compiler: m68k-linux-gcc (GCC) 9.3.0 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/0day-ci/linux/commit/259571a34d6f035f99a8343c5fcd12b6d... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Loic-Poulain/net-Add-a-WWAN-subsystem/20210312-003256 git checkout 259571a34d6f035f99a8343c5fcd12b6dfc92c40 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=m68k 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 >>): 22 | struct wwan_device *__wwan_find_by_parent(struct device *parent) | ^~~~~~~~~~~~~~~~~~~~~ vim +/__wwan_find_by_parent +22 drivers/net/wwan/wwan_core.c 21 23 { 24 struct wwan_device *wwandev; 25 26 if (!parent) 27 return NULL; 28 29 list_for_each_entry(wwandev, &wwan_list, list) { 30 if (wwandev->dev.parent == parent) 31 return wwandev; 32 } 33 34 return NULL; 35 } 36 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org