Hi Mike,

I love your patch! Perhaps something to improve:

[auto build test WARNING on lwn/docs-next]
[also build test WARNING on linus/master v5.12-rc3 next-20210316]
[cannot apply to soc/for-next]
[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/Mike-Leach/CoreSight-configuration-management-ETM-strobing/20210317-021436
base:   git://git.lwn.net/linux-2.6 docs-next
config: arm-randconfig-r035-20210316 (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://github.com/0day-ci/linux/commit/8ed7fd0cc237978b3f66769efffdbb108f920363
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Mike-Leach/CoreSight-configuration-management-ETM-strobing/20210317-021436
        git checkout 8ed7fd0cc237978b3f66769efffdbb108f920363
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

All warnings (new ones prefixed by >>):

quoted

drivers/hwtracing/coresight/coresight-etm-perf.c:647:6: warning: no previous prototype for 'etm_perf_del_symlink_group' [-Wmissing-prototypes]

     647 | void etm_perf_del_symlink_group(struct dev_ext_attribute *ea, const char *group_name)
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~


vim +/etm_perf_del_symlink_group +647 drivers/hwtracing/coresight/coresight-etm-perf.c

   646	
 > 647	void etm_perf_del_symlink_group(struct dev_ext_attribute *ea, const char *group_name)
   648	{
   649		struct device *pmu_dev = etm_pmu.dev;
   650	
   651		sysfs_remove_file_from_group(&pmu_dev->kobj,
   652					     &ea->attr.attr, group_name);
   653	}
   654	

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