kernel/sched/core.c:7355:20: warning: unused function 'balance_hotplug_wait'

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   62fb9874f5da54fdb243003b386128037319b219
commit: 198688edbf77c6fc0e65f5d062f810d83d090166 MIPS: Fix inline asm input/output type mismatch in checksum.h used with Clang
date:   5 months ago
config: mips-randconfig-r012-20210628 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 59558129276098d62046c8cda92240d292cbfb1c)
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
        # install mips cross compiling tool for clang build
        # apt-get install binutils-mips-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=198688edbf77c6fc0e65f5d062f810d83d090166
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 198688edbf77c6fc0e65f5d062f810d83d090166
        # save the attached .config to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross O=build_dir ARCH=mips SHELL=/bin/bash kernel/sched/ mm/

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

All warnings (new ones prefixed by >>):

   kernel/sched/core.c:2828:6: warning: no previous prototype for function 'sched_set_stop_task'
   void sched_set_stop_task(int cpu, struct task_struct
   ^
   kernel/sched/core.c:2828:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void sched_set_stop_task(int cpu, struct task_struct
   ^
   static
   kernel/sched/core.c:4238:13: warning: variable 'rq' set but not used
   struct rq
   ^
   kernel/sched/core.c:5176:35: warning: no previous prototype for function 'schedule_user'
   asmlinkage __visible void __sched schedule_user(void)
   ^
   kernel/sched/core.c:5176:22: note: declare 'static' if the function is not intended to be used outside of this translation unit
   asmlinkage __visible void __sched schedule_user(void)
   ^
   static
   kernel/sched/core.c:1788:20: warning: unused function 'rq_has_pinned_tasks'
   static inline bool rq_has_pinned_tasks(struct rq
   ^
>> kernel/sched/core.c:7355:20: warning: unused function 'balance_hotplug_wait'
   static inline void balance_hotplug_wait(void)
   ^
   fatal error: error in backend: Nested variants found in inline asm string: '.if ( 0x04 ) != -1)) 0x04 ) != -1)) : ($( static struct ftrace_branch_data __attribute__((__aligned__(4))) __attribute__((__section__("_ftrace_branch"))) __if_trace = $( .func = __func__, .file = "arch/mips/include/asm/barrier.h", .line = 27, $); 0x04 ) != -1)) : $))) ) && ( (1 << 0) ); .set push; .set mips64r2; .rept (1 - (0x04 == 0x04)); sync 0x04; .endr; .set pop; .else; ; .endif'
   clang-13: error: clang frontend command failed with exit code 70 (use -v to see invocation)
   clang version 13.0.0 (git://gitmirror/llvm_project 59558129276098d62046c8cda92240d292cbfb1c)
   Target: mips64el-unknown-linux-gnuabi64
   Thread model: posix
   InstalledDir: /opt/cross/clang-5955812927/bin
   clang-13: note: diagnostic msg:
   Makefile arch drivers include kernel mm scripts source usr


vim +/balance_hotplug_wait +7355 kernel/sched/core.c

dce48a84adf1806 kernel/sched.c      Thomas Gleixner 2009-04-11  7354  
f2469a1fb43f85d kernel/sched/core.c Thomas Gleixner 2020-09-14 @7355  static inline void balance_hotplug_wait(void)
f2469a1fb43f85d kernel/sched/core.c Thomas Gleixner 2020-09-14  7356  {
dce48a84adf1806 kernel/sched.c      Thomas Gleixner 2009-04-11  7357  }
f2469a1fb43f85d kernel/sched/core.c Thomas Gleixner 2020-09-14  7358  

:::::: The code at line 7355 was first introduced by commit
:::::: f2469a1fb43f85d243ce72638367fb6e15c33491 sched/core: Wait for tasks being pushed away on hotplug

:::::: TO: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
:::::: CC: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

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

Attachment: .config.gz
Description: application/gzip