1 files changed, 16 insertions, 15 deletions

diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c
index 547b1fe5b052..e4163c5af1de 100644
--- a/kernel/rcutiny.c
+++ b/kernel/rcutiny.c
@@ -56,24 +56,27 @@ static void __call_rcu(struct rcu_head *head,
 static long long rcu_dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
 
 /* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcutree.c. */
-static void rcu_idle_enter_common(long long oldval)
+static void rcu_idle_enter_common(long long newval)
 {
-        if (rcu_dynticks_nesting) {
+        if (newval) {
                 RCU_TRACE(trace_rcu_dyntick("--=",
-                                            oldval, rcu_dynticks_nesting));
+                                            rcu_dynticks_nesting, newval));
+                rcu_dynticks_nesting = newval;
                 return;
         }
-        RCU_TRACE(trace_rcu_dyntick("Start", oldval, rcu_dynticks_nesting));
+        RCU_TRACE(trace_rcu_dyntick("Start", rcu_dynticks_nesting, newval));
         if (!is_idle_task(current)) {
                 struct task_struct *idle = idle_task(smp_processor_id());
 
                 RCU_TRACE(trace_rcu_dyntick("Error on entry: not idle task",
-                                            oldval, rcu_dynticks_nesting));
+                                            rcu_dynticks_nesting, newval));
                 ftrace_dump(DUMP_ALL);
                 WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
                           current->pid, current->comm,
                           idle->pid, idle->comm); /* must be idle task! */
         }
+        barrier();
+        rcu_dynticks_nesting = newval;
         rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */
 }
 
@@ -84,17 +87,16 @@ static void rcu_idle_enter_common(long long oldval)
 void rcu_idle_enter(void)
 {
         unsigned long flags;
-        long long oldval;
+        long long newval;
 
         local_irq_save(flags);
-        oldval = rcu_dynticks_nesting;
         WARN_ON_ONCE((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0);
         if ((rcu_dynticks_nesting & DYNTICK_TASK_NEST_MASK) ==
             DYNTICK_TASK_NEST_VALUE)
-                rcu_dynticks_nesting = 0;
+                newval = 0;
         else
-                rcu_dynticks_nesting  -= DYNTICK_TASK_NEST_VALUE;
-        rcu_idle_enter_common(oldval);
+                newval = rcu_dynticks_nesting - DYNTICK_TASK_NEST_VALUE;
+        rcu_idle_enter_common(newval);
         local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(rcu_idle_enter);
@@ -105,13 +107,12 @@ EXPORT_SYMBOL_GPL(rcu_idle_enter);
 void rcu_irq_exit(void)
 {
         unsigned long flags;
-        long long oldval;
+        long long newval;
 
         local_irq_save(flags);
-        oldval = rcu_dynticks_nesting;
-        rcu_dynticks_nesting--;
-        WARN_ON_ONCE(rcu_dynticks_nesting < 0);
-        rcu_idle_enter_common(oldval);
+        newval = rcu_dynticks_nesting - 1;
+        WARN_ON_ONCE(newval < 0);
+        rcu_idle_enter_common(newval);
         local_irq_restore(flags);
 }