tree: https://git.kernel.org/pub/scm/linux/kernel/git/jirislaby/linux.git devel head: 7f6078c52635bd143cc38f0f85fbd90528e4bae5 commit: b25656716807e99cddba033240a0c000ac9da02a [12/73] tty: drop tty_flip_buffer_push config: mips-randconfig-r014-20211028 (attached as .config) compiler: mips-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 # https://git.kernel.org/pub/scm/linux/kernel/git/jirislaby/linux.git/commit/?id=b25656716807e99cddba033240a0c000ac9da02a git remote add jirislaby https://git.kernel.org/pub/scm/linux/kernel/git/jirislaby/linux.git git fetch --no-tags jirislaby devel git checkout b25656716807e99cddba033240a0c000ac9da02a # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=mips If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot All errors (new ones prefixed by >>): drivers/tty/rpmsg_tty.c: In function 'rpmsg_tty_cb': >> drivers/tty/rpmsg_tty.c:42:9: error: implicit declaration of function 'tty_flip_buffer_push' [-Werror=implicit-function-declaration] 42 | tty_flip_buffer_push(&cport->port); | ^~~~~~~~~~~~~~~~~~~~ cc1: some warnings being treated as errors vim +/tty_flip_buffer_push +42 drivers/tty/rpmsg_tty.c 7c0408d8057971 Arnaud Pouliquen 2021-10-15 31 7c0408d8057971 Arnaud Pouliquen 2021-10-15 32 static int rpmsg_tty_cb(struct rpmsg_device *rpdev, void *data, int len, void *priv, u32 src) 7c0408d8057971 Arnaud Pouliquen 2021-10-15 33 { 7c0408d8057971 Arnaud Pouliquen 2021-10-15 34 struct rpmsg_tty_port *cport = dev_get_drvdata(&rpdev->dev); 7c0408d8057971 Arnaud Pouliquen 2021-10-15 35 int copied; 7c0408d8057971 Arnaud Pouliquen 2021-10-15 36 7c0408d8057971 Arnaud Pouliquen 2021-10-15 37 if (!len) 7c0408d8057971 Arnaud Pouliquen 2021-10-15 38 return -EINVAL; 7c0408d8057971 Arnaud Pouliquen 2021-10-15 39 copied = tty_insert_flip_string(&cport->port, data, len); 7c0408d8057971 Arnaud Pouliquen 2021-10-15 40 if (copied != len) 7c0408d8057971 Arnaud Pouliquen 2021-10-15 41 dev_err_ratelimited(&rpdev->dev, "Trunc buffer: available space is %d\n", copied); 7c0408d8057971 Arnaud Pouliquen 2021-10-15 @42 tty_flip_buffer_push(&cport->port); 7c0408d8057971 Arnaud Pouliquen 2021-10-15 43 7c0408d8057971 Arnaud Pouliquen 2021-10-15 44 return 0; 7c0408d8057971 Arnaud Pouliquen 2021-10-15 45 } 7c0408d8057971 Arnaud Pouliquen 2021-10-15 46 :::::: The code at line 42 was first introduced by commit :::::: 7c0408d805797178f075f33d0f705a1c6ef76c82 tty: add rpmsg driver :::::: TO: Arnaud Pouliquen :::::: CC: Greg Kroah-Hartman --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org