tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev.2021.04.20a
head:   fe7d174b033dcf9367759b3c14febb31525aad39
commit: a1ec494e1eef0c72d8f89bbf916a4b291273d2e5 [98/101] tasks-rcu: Make show_rcu_tasks_gp_kthreads() be static inline
config: arm-spear13xx_defconfig (attached as .config)
compiler: arm-linux-gnueabi-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://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/commit/?id=a1ec494e1eef0c72d8f89bbf916a4b291273d2e5
        git remote add rcu https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
        git fetch --no-tags rcu dev.2021.04.20a
        git checkout a1ec494e1eef0c72d8f89bbf916a4b291273d2e5
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross W=1 ARCH=arm 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   In file included from kernel/rcu/update.c:584:
>> kernel/rcu/tasks.h:1404:20: error: static declaration of 'show_rcu_tasks_gp_kthreads' follows non-static declaration
    1404 | static inline void show_rcu_tasks_gp_kthreads(void) {}
         |                    ^~~~~~~~~~~~~~~~~~~~~~~~~~
   In file included from kernel/rcu/update.c:49:
   kernel/rcu/rcu.h:440:6: note: previous declaration of 'show_rcu_tasks_gp_kthreads' was here
     440 | void show_rcu_tasks_gp_kthreads(void);
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~


vim +/show_rcu_tasks_gp_kthreads +1404 kernel/rcu/tasks.h

  1401	
  1402	#else /* #ifdef CONFIG_TASKS_RCU_GENERIC */
  1403	static inline void rcu_tasks_bootup_oddness(void) {}
> 1404	static inline void show_rcu_tasks_gp_kthreads(void) {}

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org