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 changes in this cycle are:

   - Documentation updates

   - RCU CPU stall-warning updates

   - Torture-test updates

   - Miscellaneous fixes

  Size wise the biggest updates are to documentation. Excluding
  documentation most of the code increase comes from a single commit
  which expands debugging"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  srcu: Add parameters to SRCU docbook comments
  doc: Rewrite confusing statement about memory barriers
  memory-barriers.txt: Fix typo in pairing example
  rcu/segcblist: Include rcupdate.h
  rcu: Add extended-quiescent-state testing advice
  rcu: Suppress lockdep false-positive ->boost_mtx complaints
  rcu: Do not include rtmutex_common.h unconditionally
  torture: Provide TMPDIR environment variable to specify tmpdir
  rcutorture: Dump writer stack if stalled
  rcutorture: Add interrupt-disable capability to stall-warning tests
  rcu: Suppress RCU CPU stall warnings while dumping trace
  rcu: Turn off tracing before dumping trace
  rcu: Make RCU CPU stall warnings check for irq-disabled CPUs
  sched,rcu: Make cond_resched() provide RCU quiescent state
  sched: Make resched_cpu() unconditional
  irq_work: Map irq_work_on_queue() to irq_work_on() in !SMP
  rcu: Create call_rcu_tasks() kthread at boot time
  rcu: Fix up pending cbs check in rcu_prepare_for_idle
  memory-barriers: Rework multicopy-atomicity section
  memory-barriers: Replace uses of "transitive"
  ...

1 files changed, 9 insertions, 5 deletions

diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index e012b9be777e..4c857e583802 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -54,6 +54,7 @@ DEFINE_PER_CPU(char, rcu_cpu_has_work);
  * This probably needs to be excluded from -rt builds.
  */
 #define rt_mutex_owner(a) ({ WARN_ON_ONCE(1); NULL; })
+#define rt_mutex_futex_unlock(x) WARN_ON_ONCE(1)
 
 #endif /* #else #ifdef CONFIG_RCU_BOOST */
 
@@ -530,7 +531,7 @@ void rcu_read_unlock_special(struct task_struct *t)
 
 		/* Unboost if we were boosted. */
 		if (IS_ENABLED(CONFIG_RCU_BOOST) && drop_boost_mutex)
-			rt_mutex_unlock(&rnp->boost_mtx);
+			rt_mutex_futex_unlock(&rnp->boost_mtx);
 
 		/*
 		 * If this was the last task on the expedited lists,
@@ -911,8 +912,6 @@ void exit_rcu(void)
 
 #ifdef CONFIG_RCU_BOOST
 
-#include "../locking/rtmutex_common.h"
-
 static void rcu_wake_cond(struct task_struct *t, int status)
 {
 	/*
@@ -1507,7 +1506,7 @@ static void rcu_prepare_for_idle(void)
 	rdtp->last_accelerate = jiffies;
 	for_each_rcu_flavor(rsp) {
 		rdp = this_cpu_ptr(rsp->rda);
-		if (rcu_segcblist_pend_cbs(&rdp->cblist))
+		if (!rcu_segcblist_pend_cbs(&rdp->cblist))
 			continue;
 		rnp = rdp->mynode;
 		raw_spin_lock_rcu_node(rnp); /* irqs already disabled. */
@@ -1671,6 +1670,7 @@ static void print_cpu_stall_info_begin(void)
  */
 static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
 {
+	unsigned long delta;
 	char fast_no_hz[72];
 	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
 	struct rcu_dynticks *rdtp = rdp->dynticks;
@@ -1685,11 +1685,15 @@ static void print_cpu_stall_info(struct rcu_state *rsp, int cpu)
 		ticks_value = rsp->gpnum - rdp->gpnum;
 	}
 	print_cpu_stall_fast_no_hz(fast_no_hz, cpu);
-	pr_err("\t%d-%c%c%c: (%lu %s) idle=%03x/%llx/%d softirq=%u/%u fqs=%ld %s\n",
+	delta = rdp->mynode->gpnum - rdp->rcu_iw_gpnum;
+	pr_err("\t%d-%c%c%c%c: (%lu %s) idle=%03x/%llx/%d softirq=%u/%u fqs=%ld %s\n",
 	       cpu,
 	       "O."[!!cpu_online(cpu)],
 	       "o."[!!(rdp->grpmask & rdp->mynode->qsmaskinit)],
 	       "N."[!!(rdp->grpmask & rdp->mynode->qsmaskinitnext)],
+	       !IS_ENABLED(CONFIG_IRQ_WORK) ? '?' :
+			rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' :
+				"!."[!delta],
 	       ticks_value, ticks_title,
 	       rcu_dynticks_snap(rdtp) & 0xfff,
 	       rdtp->dynticks_nesting, rdtp->dynticks_nmi_nesting,