tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git dev
head:   c155a9e10fd45235f39043c9280d0e0cea89b880
commit: d0498815d6a3cda16e1c56857674938acd7cab6e [38/125] rcu: Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds
config: x86_64-randconfig-x007-201827 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-16) 7.3.0
reproduce:
        git checkout d0498815d6a3cda16e1c56857674938acd7cab6e
        # save the attached .config to linux build tree
        make ARCH=x86_64 

Note: the rcu/dev HEAD c155a9e10fd45235f39043c9280d0e0cea89b880 builds fine.
      It only hurts bisectibility.

All error/warnings (new ones prefixed by >>):

   In file included from include/linux/kernel.h:10:0,
                    from kernel/rcu/tree.c:34:
   kernel/rcu/tree_plugin.h: In function 'rcu_flavor_check_callbacks':
>> kernel/rcu/tree_plugin.h:785:14: error: implicit declaration of function 'rcu_is_cpu_rrupt_from_idle'; did you mean 'rcu_prepare_for_idle'? [-Werror=implicit-function-declaration]
     if (user || rcu_is_cpu_rrupt_from_idle()) {
                 ^
   include/linux/compiler.h:58:30: note: in definition of macro '__trace_if'
     if (__builtin_constant_p(!!(cond)) ? !!(cond) :   \
                                 ^~~~
>> kernel/rcu/tree_plugin.h:785:2: note: in expansion of macro 'if'
     if (user || rcu_is_cpu_rrupt_from_idle()) {
     ^~
   cc1: some warnings being treated as errors

vim +785 kernel/rcu/tree_plugin.h

   772	
   773	/*
   774	 * Check for a quiescent state from the current CPU.  When a task blocks,
   775	 * the task is recorded in the corresponding CPU's rcu_node structure,
   776	 * which is checked elsewhere.
   777	 *
   778	 * Caller must disable hard irqs.
   779	 */
   780	static void rcu_flavor_check_callbacks(int user)
   781	{
   782		struct rcu_state *rsp = &rcu_state;
   783		struct task_struct *t = current;
   784	
 > 785		if (user || rcu_is_cpu_rrupt_from_idle()) {
   786			rcu_note_voluntary_context_switch(current);
   787		}
   788		if (t->rcu_read_lock_nesting > 0 ||
   789		    (preempt_count() & (PREEMPT_MASK | SOFTIRQ_MASK))) {
   790			/* No QS, force context switch if deferred. */
   791			if (rcu_preempt_need_deferred_qs(t))
   792				resched_cpu(smp_processor_id());
   793		} else if (rcu_preempt_need_deferred_qs(t)) {
   794			rcu_preempt_deferred_qs(t); /* Report deferred QS. */
   795			return;
   796		} else if (!t->rcu_read_lock_nesting) {
   797			rcu_qs(); /* Report immediate QS. */
   798			return;
   799		}
   800	
   801		/* If GP is oldish, ask for help from rcu_read_unlock_special(). */
   802		if (t->rcu_read_lock_nesting > 0 &&
   803		    __this_cpu_read(rcu_data_p->core_needs_qs) &&
   804		    __this_cpu_read(rcu_data_p->cpu_no_qs.b.norm) &&
   805		    !t->rcu_read_unlock_special.b.need_qs &&
   806		    time_after(jiffies, rsp->gp_start + HZ))
   807			t->rcu_read_unlock_special.b.need_qs = true;
   808	}
   809	

---
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