1 files changed, 23 insertions, 25 deletions

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 50fee7689e71..8b4d273331e4 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -57,6 +57,7 @@
 #include <linux/random.h>
 #include <linux/trace_events.h>
 #include <linux/suspend.h>
+#include <linux/ftrace.h>
 
 #include "tree.h"
 #include "rcu.h"
@@ -771,25 +772,24 @@ cpu_needs_another_gp(struct rcu_state *rsp, struct rcu_data *rdp)
 }
 
 /*
- * rcu_eqs_enter_common - current CPU is moving towards extended quiescent state
+ * rcu_eqs_enter_common - current CPU is entering an extended quiescent state
  *
- * If the new value of the ->dynticks_nesting counter now is zero,
- * we really have entered idle, and must do the appropriate accounting.
- * The caller must have disabled interrupts.
+ * Enter idle, doing appropriate accounting.  The caller must have
+ * disabled interrupts.
  */
-static void rcu_eqs_enter_common(long long oldval, bool user)
+static void rcu_eqs_enter_common(bool user)
 {
         struct rcu_state *rsp;
         struct rcu_data *rdp;
-        RCU_TRACE(struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);)
+        struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);
 
-        trace_rcu_dyntick(TPS("Start"), oldval, rdtp->dynticks_nesting);
+        trace_rcu_dyntick(TPS("Start"), rdtp->dynticks_nesting, 0);
         if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
             !user && !is_idle_task(current)) {
                 struct task_struct *idle __maybe_unused =
                         idle_task(smp_processor_id());
 
-                trace_rcu_dyntick(TPS("Error on entry: not idle task"), oldval, 0);
+                trace_rcu_dyntick(TPS("Error on entry: not idle task"), rdtp->dynticks_nesting, 0);
                 rcu_ftrace_dump(DUMP_ORIG);
                 WARN_ONCE(1, "Current pid: %d comm: %s / Idle pid: %d comm: %s",
                           current->pid, current->comm,
@@ -800,7 +800,10 @@ static void rcu_eqs_enter_common(long long oldval, bool user)
                 do_nocb_deferred_wakeup(rdp);
         }
         rcu_prepare_for_idle();
-        rcu_dynticks_eqs_enter();
+        stack_tracer_disable();
+        rdtp->dynticks_nesting = 0; /* Breaks tracing momentarily. */
+        rcu_dynticks_eqs_enter(); /* After this, tracing works again. */
+        stack_tracer_enable();
         rcu_dynticks_task_enter();
 
         /*
@@ -821,19 +824,15 @@ static void rcu_eqs_enter_common(long long oldval, bool user)
  */
 static void rcu_eqs_enter(bool user)
 {
-        long long oldval;
         struct rcu_dynticks *rdtp;
 
         rdtp = this_cpu_ptr(&rcu_dynticks);
-        oldval = rdtp->dynticks_nesting;
         WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
-                     (oldval & DYNTICK_TASK_NEST_MASK) == 0);
-        if ((oldval & DYNTICK_TASK_NEST_MASK) == DYNTICK_TASK_NEST_VALUE) {
-                rdtp->dynticks_nesting = 0;
-                rcu_eqs_enter_common(oldval, user);
-        } else {
+                     (rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK) == 0);
+        if ((rdtp->dynticks_nesting & DYNTICK_TASK_NEST_MASK) == DYNTICK_TASK_NEST_VALUE)
+                rcu_eqs_enter_common(user);
+        else
                 rdtp->dynticks_nesting -= DYNTICK_TASK_NEST_VALUE;
-        }
 }
 
 /**
@@ -892,19 +891,18 @@ void rcu_user_enter(void)
  */
 void rcu_irq_exit(void)
 {
-        long long oldval;
         struct rcu_dynticks *rdtp;
 
         RCU_LOCKDEP_WARN(!irqs_disabled(), "rcu_irq_exit() invoked with irqs enabled!!!");
         rdtp = this_cpu_ptr(&rcu_dynticks);
-        oldval = rdtp->dynticks_nesting;
-        rdtp->dynticks_nesting--;
         WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) &&
-                     rdtp->dynticks_nesting < 0);
-        if (rdtp->dynticks_nesting)
-                trace_rcu_dyntick(TPS("--="), oldval, rdtp->dynticks_nesting);
-        else
-                rcu_eqs_enter_common(oldval, true);
+                     rdtp->dynticks_nesting < 1);
+        if (rdtp->dynticks_nesting <= 1) {
+                rcu_eqs_enter_common(true);
+        } else {
+                trace_rcu_dyntick(TPS("--="), rdtp->dynticks_nesting, rdtp->dynticks_nesting - 1);
+                rdtp->dynticks_nesting--;
+        }
         rcu_sysidle_enter(1);
 }