Hi Christophe,

I love your patch! Yet something to improve:

[auto build test ERROR on powerpc/next]
[also build test ERROR on linus/master v5.13-rc1 next-20210512]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Christophe-Leroy/kprobes-Allow-architectures-to-override-optinsn-page-allocation/20210512-223121
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc-ppc64_defconfig (attached as .config)
compiler: powerpc64-linux-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://github.com/0day-ci/linux/commit/1cc4bb503e4ee4839247b767883c8b860b26413c
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Christophe-Leroy/kprobes-Allow-architectures-to-override-optinsn-page-allocation/20210512-223121
        git checkout 1cc4bb503e4ee4839247b767883c8b860b26413c
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross W=1 ARCH=powerpc 

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 >>):

>> arch/powerpc/kernel/optprobes.c:36:7: error: no previous prototype for 'alloc_optinsn_page' [-Werror=missing-prototypes]
      36 | void *alloc_optinsn_page(void)
         |       ^~~~~~~~~~~~~~~~~~
>> arch/powerpc/kernel/optprobes.c:44:6: error: no previous prototype for 'free_optinsn_page' [-Werror=missing-prototypes]
      44 | void free_optinsn_page(void *page)
         |      ^~~~~~~~~~~~~~~~~
   cc1: all warnings being treated as errors


vim +/alloc_optinsn_page +36 arch/powerpc/kernel/optprobes.c

    35	
  > 36	void *alloc_optinsn_page(void)
    37	{
    38		if (insn_page_in_use)
    39			return NULL;
    40		insn_page_in_use = true;
    41		return &optinsn_slot;
    42	}
    43	
  > 44	void free_optinsn_page(void *page)
    45	{
    46		insn_page_in_use = false;
    47	}
    48	

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