tree: https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-5.12.y-rt-rebase head: 2664a7f5d3d24da4b2657a1e933181d376b77616 commit: e757cbebec298e80e5b3378392f2de2a5f380ae7 [35/193] printk: add pr_flush() config: mips-randconfig-r016-20210318 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 436c6c9c20cc522c92a923440a5fc509c342a7db) 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 mips cross compiling tool for clang build # apt-get install binutils-mips-linux-gnu # https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/com... git remote add linux-rt-devel https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git git fetch --no-tags linux-rt-devel linux-5.12.y-rt-rebase git checkout e757cbebec298e80e5b3378392f2de2a5f380ae7 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): kernel/printk/printk.c:178:5: warning: no previous prototype for function 'devkmsg_sysctl_set_loglvl' [-Wmissing-prototypes] int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, ^ kernel/printk/printk.c:178:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int devkmsg_sysctl_set_loglvl(struct ctl_table *table, int write, ^ static kernel/printk/printk.c:2674:4: error: implicit declaration of function 'latched_seq_write' [-Werror,-Wimplicit-function-declaration] latched_seq_write(&c->printk_seq, seq); ^ kernel/printk/printk.c:2907:2: error: implicit declaration of function 'latched_seq_write' [-Werror,-Wimplicit-function-declaration] latched_seq_write(&newcon->printk_seq, seq); ^ printk_seq = read_console_seq(con); ^ kernel/printk/printk.c:3633:17: note: did you mean '__up_console_sem'? kernel/printk/printk.c:238:13: note: '__up_console_sem' declared here static void __up_console_sem(unsigned long ip) ^ 1 warning and 3 errors generated. vim +/read_console_seq +3633 kernel/printk/printk.c 3597 3598 /** 3599 * pr_flush() - Wait for printing threads to catch up. 3600 * 3601 * @timeout_ms: The maximum time (in ms) to wait. 3602 * @reset_on_progress: Reset the timeout if forward progress is seen. 3603 * 3604 * A value of 0 for @timeout_ms means no waiting will occur. A value of -1 3605 * represents infinite waiting. 3606 * 3607 * If @reset_on_progress is true, the timeout will be reset whenever any 3608 * printer has been seen to make some forward progress. 3609 * 3610 * Context: Any context. 3611 * Return: true if all enabled printers are caught up. 3612 */ 3613 bool pr_flush(int timeout_ms, bool reset_on_progress) 3614 { 3615 int remaining = timeout_ms; 3616 struct console *con; 3617 u64 last_diff = 0; 3618 bool may_sleep; 3619 u64 printk_seq; 3620 u64 diff; 3621 u64 seq; 3622 3623 may_sleep = (preemptible() && !in_softirq()); 3624 3625 seq = prb_next_seq(prb); 3626 3627 for (;;) { 3628 diff = 0; 3629 3630 for_each_console(con) { 3631 if (!(con->flags & CON_ENABLED)) 3632 continue; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org