[jolsa-perf:bpf/batch 8/27] samples/ftrace/ftrace-direct-multi.c:8:6: warning: no previous prototype for 'my_direct_func'

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git bpf/batch
head:   b81b17307e02f8e6d4abf87e7ec2d7e5aea1e0b5
commit: 8243d2b414777d88faa88bada9b2ce204d7fcec0 [8/27] ftrace/samples: Add multi direct interface test module
config: x86_64-randconfig-r013-20210827 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git/commit/?id=8243d2b414777d88faa88bada9b2ce204d7fcec0
        git remote add jolsa-perf https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
        git fetch --no-tags jolsa-perf bpf/batch
        git checkout 8243d2b414777d88faa88bada9b2ce204d7fcec0
        # save the attached .config to linux build tree
        make W=1 ARCH=x86_64 

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

All warnings (new ones prefixed by >>):

>> samples/ftrace/ftrace-direct-multi.c:8:6: warning: no previous prototype for 'my_direct_func' [-Wmissing-prototypes]
       8 | void my_direct_func(unsigned long ip)
         |      ^~~~~~~~~~~~~~


vim +/my_direct_func +8 samples/ftrace/ftrace-direct-multi.c

     7	
   > 8	void my_direct_func(unsigned long ip)
     9	{
    10		trace_printk("ip %lx\n", ip);
    11	}
    12	

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Attachment: .config.gz
Description: application/gzip