Hi Andrei,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on soc/for-next]
[also build test WARNING on arm/for-next xlnx/master kvmarm/next v5.7]
[cannot apply to arm64/for-next/core next-20200602]
[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/Andrei-Vagin/arm64-add-the-time-namespace-support/20200603-020504
base:   https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git for-next
config: arm64-allnoconfig (attached as .config)
compiler: aarch64-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
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 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 <<):

>> arch/arm64/kernel/vdso.c:93:19: warning: no previous prototype for 'arch_get_vdso_data' [-Wmissing-prototypes]
93 | struct vdso_data *arch_get_vdso_data(void *vvar_page)
|                   ^~~~~~~~~~~~~~~~~~

vim +/arch_get_vdso_data +93 arch/arm64/kernel/vdso.c

    91	
    92	
  > 93	struct vdso_data *arch_get_vdso_data(void *vvar_page)
    94	{
    95		return (struct vdso_data *)(vvar_page);
    96	}
    97	

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