arch/riscv/kernel/perf_callchain.c:77:6: warning: no previous prototype for 'fill_callchain'

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   cd77006e01b3198c75fb7819b3d0ff89709539bb
commit: dbeb90b0c1eb86a9b963b929d3c937afb7dadfa3 riscv: Add perf callchain support
date:   10 months ago
config: riscv-randconfig-r034-20200701 (attached as .config)
compiler: riscv32-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
        git checkout dbeb90b0c1eb86a9b963b929d3c937afb7dadfa3
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=riscv 

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

All warnings (new ones prefixed by >>):

   In file included from include/linux/perf_event.h:25,
                    from arch/riscv/kernel/perf_callchain.c:4:
   arch/riscv/include/asm/perf_event.h:26:2: error: #error "Please provide a valid RISCV_MAX_COUNTERS for the PMU."
      26 | #error "Please provide a valid RISCV_MAX_COUNTERS for the PMU."
         |  ^~~~~
   arch/riscv/include/asm/perf_event.h:54:28: error: 'RISCV_MAX_COUNTERS' undeclared here (not in a function); did you mean 'RISCV_BASE_COUNTERS'?
      54 |  struct perf_event *events[RISCV_MAX_COUNTERS];
         |                            ^~~~~~~~~~~~~~~~~~
         |                            RISCV_BASE_COUNTERS
>> arch/riscv/kernel/perf_callchain.c:77:6: warning: no previous prototype for 'fill_callchain' [-Wmissing-prototypes]
      77 | bool fill_callchain(unsigned long pc, void *entry)
         |      ^~~~~~~~~~~~~~

vim +/fill_callchain +77 arch/riscv/kernel/perf_callchain.c

    76	
  > 77	bool fill_callchain(unsigned long pc, void *entry)
    78	{
    79		return perf_callchain_store(entry, pc);
    80	}
    81	

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

Attachment: .config.gz
Description: application/gzip