[rt-devel:linux-6.3.y-rt-rebase 44/77] kernel/printk/printk.c:3370:6: warning: no previous prototype for function 'console_bkl_kthread_create'

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-6.3.y-rt-rebase
head:   35ea14bea980c7f5e134ba962f64c1d1376f88f8
commit: 28b0eb3e1cf4791cba0be98b5103be3f077ad5d1 [44/77] printk: Add threaded printing support for BKL consoles.
config: arm64-randconfig-r001-20230428 (https://download.01.org/0day-ci/archive/20230428/202304280656.BBdRteur-lkp@intel.com/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project 437b7602e4a998220871de78afcb020b9c14a661)
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 arm64 cross compiling tool for clang build
        # apt-get install binutils-aarch64-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/commit/?id=28b0eb3e1cf4791cba0be98b5103be3f077ad5d1
        git remote add rt-devel https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git
        git fetch --no-tags rt-devel linux-6.3.y-rt-rebase
        git checkout 28b0eb3e1cf4791cba0be98b5103be3f077ad5d1
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm64 SHELL=/bin/bash kernel/printk/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202304280656.BBdRteur-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> kernel/printk/printk.c:3370:6: warning: no previous prototype for function 'console_bkl_kthread_create' [-Wmissing-prototypes]
   void console_bkl_kthread_create(void)
        ^
   kernel/printk/printk.c:3370:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void console_bkl_kthread_create(void)
   ^
   static 
   1 warning generated.


vim +/console_bkl_kthread_create +3370 kernel/printk/printk.c

  3369	
> 3370	void console_bkl_kthread_create(void)
  3371	{
  3372		struct task_struct *kt;
  3373		struct console *c;
  3374	
  3375		lockdep_assert_held(&console_mutex);
  3376	
  3377		if (!IS_ENABLED(CONFIG_PREEMPT_RT))
  3378			return;
  3379	
  3380		if (!printk_threads_enabled || console_bkl_kthread)
  3381			return;
  3382	
  3383		for_each_console(c) {
  3384			if (c->flags & CON_BOOT)
  3385				return;
  3386		}
  3387	
  3388		kt = kthread_run(console_bkl_kthread_func, NULL, "pr/bkl");
  3389		if (IS_ERR(kt)) {
  3390			pr_err("unable to start BKL printing thread\n");
  3391			return;
  3392		}
  3393	
  3394		console_bkl_kthread = kt;
  3395	
  3396		/*
  3397		 * It is important that console printing threads are scheduled
  3398		 * shortly after a printk call and with generous runtime budgets.
  3399		 */
  3400		sched_set_normal(console_bkl_kthread, -20);
  3401	}
  3402	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests