Hi William,

I love your patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[also build test WARNING on v5.7-rc6 next-20200519]
[cannot apply to stm32/stm32-next linux/master]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/William-Breathitt-Gray/Introduce-the-Counter-character-device-interface/20200517-032530
base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 12bf0b632ed090358cbf03e323e5342212d0b2e4
config: arm64-randconfig-r026-20200519 (attached as .config)
compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 135b877874fae96b4372c8a3fbfaa8ff44ff86e3)
reproduce:
        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
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm64 

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

All warnings (new ones prefixed by >>, old ones prefixed by <<):

>> drivers/counter/counter-sysfs.c:850:5: warning: no previous prototype for function 'counter_sysfs_add' [-Wmissing-prototypes]
int counter_sysfs_add(struct counter_device *const counter)
^
drivers/counter/counter-sysfs.c:850:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
int counter_sysfs_add(struct counter_device *const counter)
^
static
>> drivers/counter/counter-sysfs.c:876:6: warning: no previous prototype for function 'counter_sysfs_free' [-Wmissing-prototypes]
void counter_sysfs_free(struct counter_device *const counter)
^
drivers/counter/counter-sysfs.c:876:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
void counter_sysfs_free(struct counter_device *const counter)
^
static
2 warnings generated.

vim +/counter_sysfs_add +850 drivers/counter/counter-sysfs.c

   849	
 > 850	int counter_sysfs_add(struct counter_device *const counter)
   851	{
   852		int err;
   853	
   854		/* Initialize Synapse names list */
   855		INIT_LIST_HEAD(&counter->dynamic_names_list);
   856	
   857		/* Prepare device attributes */
   858		err = counter_groups_list_prepare(counter);
   859		if (err)
   860			goto err_free_names;
   861	
   862		/* Organize device attributes to groups and match to device */
   863		err = counter_groups_prepare(counter);
   864		if (err)
   865			goto err_free_groups_list;
   866	
   867		return 0;
   868	
   869	err_free_groups_list:
   870		counter_groups_list_free(counter);
   871	err_free_names:
   872		counter_dynamic_names_free(&counter->dynamic_names_list);
   873		return err;
   874	}
   875	
 > 876	void counter_sysfs_free(struct counter_device *const counter)

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