[ammarfaizi2-block:google/android/kernel/common/android13-5.10 9989/9999] main.c:118:5: warning: no previous prototype for 'eprintf'

[kernel test robot]

tree:   https://github.com/ammarfaizi2/linux-block google/android/kernel/common/android13-5.10
head:   976a28295a01db618903406bd67cae53a4c29832
commit: 44b9bfcd4cdbc57889a0fecf79a6d30237f21bed [9989/9999] FROMGIT: tools/resolve_btfids: Build with host flags
config: x86_64-rhel-8.3-kselftests (https://download.01.org/0day-ci/archive/20220119/202201191239.XKS6Ud9B-lkp@xxxxxxxxx/config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/ammarfaizi2/linux-block/commit/44b9bfcd4cdbc57889a0fecf79a6d30237f21bed
        git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block
        git fetch --no-tags ammarfaizi2-block google/android/kernel/common/android13-5.10
        git checkout 44b9bfcd4cdbc57889a0fecf79a6d30237f21bed
        # save the config file to linux build tree
        mkdir build_dir
        make W=1 O=build_dir ARCH=x86_64 prepare

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

All warnings (new ones prefixed by >>):

>> main.c:118:5: warning: no previous prototype for 'eprintf' [-Wmissing-prototypes]
     118 | int eprintf(int level, int var, const char *fmt, ...)
         |     ^~~~~~~
   main.c: In function 'symbols_collect':
   main.c:407:7: warning: unused variable 'err' [-Wunused-variable]
     407 |   int err = -1;
         |       ^~~
   main.c:404:9: warning: unused variable 'tmp' [-Wunused-variable]
     404 |   char *tmp, *prefix;
         |         ^~~
   main.c: In function 'eprintf':
>> main.c:128:9: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized]
     128 |  return ret;
         |         ^~~

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