Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RCU updates from Ingo Molnar:
 "The main RCU changes in this cycle were:

   - Updates to use cond_resched() instead of cond_resched_rcu_qs()
     where feasible (currently everywhere except in kernel/rcu and in
     kernel/torture.c). Also a couple of fixes to avoid sending IPIs to
     offline CPUs.

   - Updates to simplify RCU's dyntick-idle handling.

   - Updates to remove almost all uses of smp_read_barrier_depends() and
     read_barrier_depends().

   - Torture-test updates.

   - Miscellaneous fixes"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (72 commits)
  torture: Save a line in stutter_wait(): while -> for
  torture: Eliminate torture_runnable and perf_runnable
  torture: Make stutter less vulnerable to compilers and races
  locking/locktorture: Fix num reader/writer corner cases
  locking/locktorture: Fix rwsem reader_delay
  torture: Place all torture-test modules in one MAINTAINERS group
  rcutorture/kvm-build.sh: Skip build directory check
  rcutorture: Simplify functions.sh include path
  rcutorture: Simplify logging
  rcutorture/kvm-recheck-*: Improve result directory readability check
  rcutorture/kvm.sh: Support execution from any directory
  rcutorture/kvm.sh: Use consistent help text for --qemu-args
  rcutorture/kvm.sh: Remove unused variable, `alldone`
  rcutorture: Remove unused script, config2frag.sh
  rcutorture/configinit: Fix build directory error message
  rcutorture: Preempt RCU-preempt readers more vigorously
  torture: Reduce #ifdefs for preempt_schedule()
  rcu: Remove have_rcu_nocb_mask from tree_plugin.h
  rcu: Add comment giving debug strategy for double call_rcu()
  tracing, rcu: Hide trace event rcu_nocb_wake when not used
  ...

kernel/trace/trace.c

@@ -2689,17 +2689,6 @@ void __trace_stack(struct trace_array *tr, unsigned long flags, int skip,
 	if (unlikely(in_nmi()))
 		return;
 
-	/*
-	 * It is possible that a function is being traced in a
-	 * location that RCU is not watching. A call to
-	 * rcu_irq_enter() will make sure that it is, but there's
-	 * a few internal rcu functions that could be traced
-	 * where that wont work either. In those cases, we just
-	 * do nothing.
-	 */
-	if (unlikely(rcu_irq_enter_disabled()))
-		return;
-
 	rcu_irq_enter_irqson();
 	__ftrace_trace_stack(buffer, flags, skip, pc, NULL);
 	rcu_irq_exit_irqson();

kernel/trace/trace_benchmark.c

@@ -165,7 +165,7 @@ static int benchmark_event_kthread(void *arg)
 		 * this thread will never voluntarily schedule which would
 		 * block synchronize_rcu_tasks() indefinitely.
 		 */
-		cond_resched_rcu_qs();
+		cond_resched();
 	}
 
 	return 0;