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* [mark:arm64/preempt-dynamic-static-key 6/6] kernel/sched/core.c:6435:43: warning: no previous prototype for function 'preempt_schedule'
@ 2021-11-20 19:25 kernel test robot
  0 siblings, 0 replies; only message in thread
From: kernel test robot @ 2021-11-20 19:25 UTC (permalink / raw)
  To: Mark Rutland; +Cc: llvm, kbuild-all, linux-kernel

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git arm64/preempt-dynamic-static-key
head:   47c5f8b3abb64dcd6ac43521d24ca9e7d7891dcc
commit: 47c5f8b3abb64dcd6ac43521d24ca9e7d7891dcc [6/6] arm64: support PREEMPT_DYNAMIC
config: arm64-buildonly-randconfig-r004-20211118 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project c46becf500df2a7fb4b4fce16178a036c344315a)
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 arm64 cross compiling tool for clang build
        # apt-get install binutils-aarch64-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/commit/?id=47c5f8b3abb64dcd6ac43521d24ca9e7d7891dcc
        git remote add mark https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git
        git fetch --no-tags mark arm64/preempt-dynamic-static-key
        git checkout 47c5f8b3abb64dcd6ac43521d24ca9e7d7891dcc
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=arm64 

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

All warnings (new ones prefixed by >>):

   kernel/sched/core.c:3439:6: warning: no previous prototype for function 'sched_set_stop_task' [-Wmissing-prototypes]
   void sched_set_stop_task(int cpu, struct task_struct *stop)
        ^
   kernel/sched/core.c:3439:1: 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 *stop)
   ^
   static 
   kernel/sched/core.c:6359:35: warning: no previous prototype for function 'schedule_user' [-Wmissing-prototypes]
   asmlinkage __visible void __sched schedule_user(void)
                                     ^
   kernel/sched/core.c:6359:22: 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:6435:43: warning: no previous prototype for function 'preempt_schedule' [-Wmissing-prototypes]
   asmlinkage __visible void __sched notrace preempt_schedule(void)
                                             ^
   kernel/sched/core.c:6435:22: note: declare 'static' if the function is not intended to be used outside of this translation unit
   asmlinkage __visible void __sched notrace preempt_schedule(void)
                        ^
                        static 
>> kernel/sched/core.c:6483:43: warning: no previous prototype for function 'preempt_schedule_notrace' [-Wmissing-prototypes]
   asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
                                             ^
   kernel/sched/core.c:6483:22: note: declare 'static' if the function is not intended to be used outside of this translation unit
   asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
                        ^
                        static 
   4 warnings generated.


vim +/preempt_schedule +6435 kernel/sched/core.c

a18b5d01819235 kernel/sched/core.c Frederic Weisbecker    2015-01-22  6429  
c1a280b68d4e6b kernel/sched/core.c Thomas Gleixner        2019-07-26  6430  #ifdef CONFIG_PREEMPTION
^1da177e4c3f41 kernel/sched.c      Linus Torvalds         2005-04-16  6431  /*
a49b4f4012ef23 kernel/sched/core.c Valentin Schneider     2019-09-23  6432   * This is the entry point to schedule() from in-kernel preemption
a49b4f4012ef23 kernel/sched/core.c Valentin Schneider     2019-09-23  6433   * off of preempt_enable.
^1da177e4c3f41 kernel/sched.c      Linus Torvalds         2005-04-16  6434   */
722a9f9299ca72 kernel/sched/core.c Andi Kleen             2014-05-02 @6435  asmlinkage __visible void __sched notrace preempt_schedule(void)
^1da177e4c3f41 kernel/sched.c      Linus Torvalds         2005-04-16  6436  {
^1da177e4c3f41 kernel/sched.c      Linus Torvalds         2005-04-16  6437  	/*
^1da177e4c3f41 kernel/sched.c      Linus Torvalds         2005-04-16  6438  	 * If there is a non-zero preempt_count or interrupts are disabled,
^1da177e4c3f41 kernel/sched.c      Linus Torvalds         2005-04-16  6439  	 * we do not want to preempt the current task. Just return..
^1da177e4c3f41 kernel/sched.c      Linus Torvalds         2005-04-16  6440  	 */
fbb00b568bc930 kernel/sched/core.c Frederic Weisbecker    2013-06-19  6441  	if (likely(!preemptible()))
^1da177e4c3f41 kernel/sched.c      Linus Torvalds         2005-04-16  6442  		return;
a18b5d01819235 kernel/sched/core.c Frederic Weisbecker    2015-01-22  6443  	preempt_schedule_common();
^1da177e4c3f41 kernel/sched.c      Linus Torvalds         2005-04-16  6444  }
376e242429bf85 kernel/sched/core.c Masami Hiramatsu       2014-04-17  6445  NOKPROBE_SYMBOL(preempt_schedule);
^1da177e4c3f41 kernel/sched.c      Linus Torvalds         2005-04-16  6446  EXPORT_SYMBOL(preempt_schedule);
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6447  
2c9a98d3bc8087 kernel/sched/core.c Peter Zijlstra (Intel  2021-01-18  6448) #ifdef CONFIG_PREEMPT_DYNAMIC
19f12e212caad8 kernel/sched/core.c Mark Rutland           2021-11-09  6449  #if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
67bb8fb8cf8e8a kernel/sched/core.c Mark Rutland           2021-11-09  6450  #ifndef preempt_schedule_dynamic_enabled
67bb8fb8cf8e8a kernel/sched/core.c Mark Rutland           2021-11-09  6451  #define preempt_schedule_dynamic_enabled	preempt_schedule
67bb8fb8cf8e8a kernel/sched/core.c Mark Rutland           2021-11-09  6452  #define preempt_schedule_dynamic_disabled	NULL
67bb8fb8cf8e8a kernel/sched/core.c Mark Rutland           2021-11-09  6453  #endif
67bb8fb8cf8e8a kernel/sched/core.c Mark Rutland           2021-11-09  6454  DEFINE_STATIC_CALL(preempt_schedule, preempt_schedule_dynamic_enabled);
ef72661e28c64a kernel/sched/core.c Peter Zijlstra         2021-01-25  6455  EXPORT_STATIC_CALL_TRAMP(preempt_schedule);
19f12e212caad8 kernel/sched/core.c Mark Rutland           2021-11-09  6456  #elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
19f12e212caad8 kernel/sched/core.c Mark Rutland           2021-11-09  6457  static DEFINE_STATIC_KEY_TRUE(sk_dynamic_preempt_schedule);
19f12e212caad8 kernel/sched/core.c Mark Rutland           2021-11-09  6458  void __sched notrace dynamic_preempt_schedule(void)
19f12e212caad8 kernel/sched/core.c Mark Rutland           2021-11-09  6459  {
19f12e212caad8 kernel/sched/core.c Mark Rutland           2021-11-09  6460  	if (!static_branch_unlikely(&sk_dynamic_preempt_schedule))
19f12e212caad8 kernel/sched/core.c Mark Rutland           2021-11-09  6461  		return;
19f12e212caad8 kernel/sched/core.c Mark Rutland           2021-11-09  6462  	preempt_schedule();
19f12e212caad8 kernel/sched/core.c Mark Rutland           2021-11-09  6463  }
19f12e212caad8 kernel/sched/core.c Mark Rutland           2021-11-09  6464  NOKPROBE_SYMBOL(dynamic_preempt_schedule);
19f12e212caad8 kernel/sched/core.c Mark Rutland           2021-11-09  6465  EXPORT_SYMBOL(dynamic_preempt_schedule);
19f12e212caad8 kernel/sched/core.c Mark Rutland           2021-11-09  6466  #endif
2c9a98d3bc8087 kernel/sched/core.c Peter Zijlstra (Intel  2021-01-18  6467) #endif
2c9a98d3bc8087 kernel/sched/core.c Peter Zijlstra (Intel  2021-01-18  6468) 
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6469  /**
4eaca0a887eaee kernel/sched/core.c Frederic Weisbecker    2015-06-04  6470   * preempt_schedule_notrace - preempt_schedule called by tracing
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6471   *
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6472   * The tracing infrastructure uses preempt_enable_notrace to prevent
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6473   * recursion and tracing preempt enabling caused by the tracing
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6474   * infrastructure itself. But as tracing can happen in areas coming
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6475   * from userspace or just about to enter userspace, a preempt enable
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6476   * can occur before user_exit() is called. This will cause the scheduler
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6477   * to be called when the system is still in usermode.
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6478   *
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6479   * To prevent this, the preempt_enable_notrace will use this function
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6480   * instead of preempt_schedule() to exit user context if needed before
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6481   * calling the scheduler.
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6482   */
4eaca0a887eaee kernel/sched/core.c Frederic Weisbecker    2015-06-04 @6483  asmlinkage __visible void __sched notrace preempt_schedule_notrace(void)
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6484  {
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6485  	enum ctx_state prev_ctx;
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6486  
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6487  	if (likely(!preemptible()))
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6488  		return;
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6489  
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6490  	do {
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6491  		/*
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6492  		 * Because the function tracer can trace preempt_count_sub()
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6493  		 * and it also uses preempt_enable/disable_notrace(), if
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6494  		 * NEED_RESCHED is set, the preempt_enable_notrace() called
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6495  		 * by the function tracer will call this function again and
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6496  		 * cause infinite recursion.
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6497  		 *
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6498  		 * Preemption must be disabled here before the function
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6499  		 * tracer can trace. Break up preempt_disable() into two
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6500  		 * calls. One to disable preemption without fear of being
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6501  		 * traced. The other to still record the preemption latency,
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6502  		 * which can also be traced by the function tracer.
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6503  		 */
3d8f74dd4ca1da kernel/sched/core.c Peter Zijlstra         2015-09-28  6504  		preempt_disable_notrace();
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6505  		preempt_latency_start(1);
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6506  		/*
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6507  		 * Needs preempt disabled in case user_exit() is traced
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6508  		 * and the tracer calls preempt_enable_notrace() causing
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6509  		 * an infinite recursion.
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6510  		 */
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6511  		prev_ctx = exception_enter();
b4bfa3fcfe3b82 kernel/sched/core.c Thomas Gleixner        2021-08-15  6512  		__schedule(SM_PREEMPT);
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6513  		exception_exit(prev_ctx);
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6514  
47252cfbac0364 kernel/sched/core.c Steven Rostedt         2016-03-21  6515  		preempt_latency_stop(1);
3d8f74dd4ca1da kernel/sched/core.c Peter Zijlstra         2015-09-28  6516  		preempt_enable_no_resched_notrace();
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6517  	} while (need_resched());
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6518  }
4eaca0a887eaee kernel/sched/core.c Frederic Weisbecker    2015-06-04  6519  EXPORT_SYMBOL_GPL(preempt_schedule_notrace);
009f60e2763568 kernel/sched/core.c Oleg Nesterov          2014-10-05  6520  

:::::: The code at line 6435 was first introduced by commit
:::::: 722a9f9299ca720a3f14660e7c0dce7b76a9cb42 asmlinkage: Add explicit __visible to drivers/*, lib/*, kernel/*

:::::: TO: Andi Kleen <ak@linux.intel.com>
:::::: CC: H. Peter Anvin <hpa@linux.intel.com>

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

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