linux-kernel - [frederic-dynticks:rcu/context-tracking 13/19] kernel/context_tracking.c:91:4: error: implicit declaration of function 'rcu_irq_work

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Date:   Thu, 3 Mar 2022 07:11:12 +0800
From:   kernel test robot <lkp@...el.com>
To:     Frederic Weisbecker <frederic@...nel.org>
Cc:     llvm@...ts.linux.dev, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org
Subject: [frederic-dynticks:rcu/context-tracking 13/19]
 kernel/context_tracking.c:91:4: error: implicit declaration of function
 'rcu_irq_work_resched'

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git rcu/context-tracking
head:   e4eaff86ec91c1cbde9a113cf5232dac9f897337
commit: 5cb63f8df32ee1a43ca46337d6c8554a27d44165 [13/19] rcu/context-tracking: Move deferred nocb resched to context tracking
config: x86_64-randconfig-a001 (https://download.01.org/0day-ci/archive/20220303/202203030735.RQy2zusl-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project d271fc04d5b97b12e6b797c6067d3c96a8d7470e)
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
        # https://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git/commit/?id=5cb63f8df32ee1a43ca46337d6c8554a27d44165
        git remote add frederic-dynticks https://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
        git fetch --no-tags frederic-dynticks rcu/context-tracking
        git checkout 5cb63f8df32ee1a43ca46337d6c8554a27d44165
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash

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

All errors (new ones prefixed by >>):

>> kernel/context_tracking.c:91:4: error: implicit declaration of function 'rcu_irq_work_resched' [-Werror,-Wimplicit-function-declaration]
                           rcu_irq_work_resched();
                           ^
   1 error generated.


vim +/rcu_irq_work_resched +91 kernel/context_tracking.c

    51	
    52	/**
    53	 * __ct_user_enter - Inform the context tracking that the CPU is going
    54	 *		     to enter user or guest space mode.
    55	 *
    56	 * This function must be called right before we switch from the kernel
    57	 * to user or guest space, when it's guaranteed the remaining kernel
    58	 * instructions to execute won't use any RCU read side critical section
    59	 * because this function sets RCU in extended quiescent state.
    60	 */
    61	void noinstr __ct_user_enter(enum ctx_state state)
    62	{
    63		lockdep_assert_irqs_disabled();
    64	
    65		/* Kernel threads aren't supposed to go to userspace */
    66		WARN_ON_ONCE(!current->mm);
    67	
    68		if (!context_tracking_recursion_enter())
    69			return;
    70	
    71		if ( __this_cpu_read(context_tracking.state) != state) {
    72			if (__this_cpu_read(context_tracking.active)) {
    73				/*
    74				 * At this stage, only low level arch entry code remains and
    75				 * then we'll run in userspace. We can assume there won't be
    76				 * any RCU read-side critical section until the next call to
    77				 * user_exit() or ct_irq_enter(). Let's remove RCU's dependency
    78				 * on the tick.
    79				 */
    80				if (state == CONTEXT_USER) {
    81					instrumentation_begin();
    82					trace_user_enter(0);
    83					vtime_user_enter(current);
    84					instrumentation_end();
    85				}
    86				/*
    87				 * Other than generic entry implementation, we may be past the last
    88				 * rescheduling opportunity in the entry code. Trigger a self IPI
    89				 * that will fire and reschedule once we resume in user/guest mode.
    90				 */
  > 91				rcu_irq_work_resched();
    92				rcu_user_enter();
    93			}
    94			/*
    95			 * Even if context tracking is disabled on this CPU, because it's outside
    96			 * the full dynticks mask for example, we still have to keep track of the
    97			 * context transitions and states to prevent inconsistency on those of
    98			 * other CPUs.
    99			 * If a task triggers an exception in userspace, sleep on the exception
   100			 * handler and then migrate to another CPU, that new CPU must know where
   101			 * the exception returns by the time we call exception_exit().
   102			 * This information can only be provided by the previous CPU when it called
   103			 * exception_enter().
   104			 * OTOH we can spare the calls to vtime and RCU when context_tracking.active
   105			 * is false because we know that CPU is not tickless.
   106			 */
   107			__this_cpu_write(context_tracking.state, state);
   108		}
   109		context_tracking_recursion_exit();
   110	}
   111	EXPORT_SYMBOL_GPL(__ct_user_enter);
   112	

---
0-DAY CI Kernel Test Service, Intel Corporation
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