tree: https://git.kernel.org/pub/scm/linux/kernel/git/jirislaby/linux.git devel head: ab00d8ca266aab3b71f64266a2351dfce6baadfb commit: 998695ea4c020601bfa37c3cb6559e48c420b286 [67/107] extract mxser_ioctl_op_mode config: x86_64-randconfig-a006-20210318 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project fcc1ce00931751ac02498986feb37744e9ace8de) 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 # install x86_64 cross compiling tool for clang build # apt-get install binutils-x86-64-linux-gnu # https://git.kernel.org/pub/scm/linux/kernel/git/jirislaby/linux.git/commi... git remote add jirislaby https://git.kernel.org/pub/scm/linux/kernel/git/jirislaby/linux.git git fetch --no-tags jirislaby devel git checkout 998695ea4c020601bfa37c3cb6559e48c420b286 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 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 >>): int mxser_ioctl_op_mode(struct mxser_port *port, int index, bool set, ^ drivers/tty/mxser.c:1401:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int mxser_ioctl_op_mode(struct mxser_port *port, int index, bool set, ^ static 1 warning generated. vim +/mxser_ioctl_op_mode +1401 drivers/tty/mxser.c 1399 1400 /* We should likely switch to TIOCGRS485/TIOCSRS485. */ 1402 int __user *u_opmode) 1403 { 1404 static const unsigned char ModeMask[] = { 0xfc, 0xf3, 0xcf, 0x3f }; 1405 int opmode, p = index % 4; 1406 int shiftbit = p * 2; 1407 unsigned char val, mask; 1408 1409 if (port->board->chip_flag != MOXA_MUST_MU860_HWID) 1410 return -EFAULT; 1411 1412 if (set) { 1413 if (get_user(opmode, u_opmode)) 1414 return -EFAULT; 1415 1416 if (opmode != RS232_MODE && opmode != RS485_2WIRE_MODE && 1417 opmode != RS422_MODE && 1418 opmode != RS485_4WIRE_MODE) 1419 return -EFAULT; 1420 1421 mask = ModeMask[p]; 1422 1423 spin_lock_irq(&port->slock); 1424 val = inb(port->opmode_ioaddr); 1425 val &= mask; 1426 val |= (opmode << shiftbit); 1427 outb(val, port->opmode_ioaddr); 1428 spin_unlock_irq(&port->slock); 1429 } else { 1430 spin_lock_irq(&port->slock); 1431 opmode = inb(port->opmode_ioaddr) >> shiftbit; 1432 spin_unlock_irq(&port->slock); 1433 1434 opmode &= OP_MODE_MASK; 1435 if (put_user(opmode, u_opmode)) 1436 return -EFAULT; 1437 } 1438 1439 return 0; 1440 } 1441 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org