rcu: Use rcu_gp_kthread_wake() to wake up grace period kthreads

[platform/adaptation/renesas_rcar/renesas_kernel.git] / kernel / rcu / tree.c

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index b3d116c..6705d94 100644 (file)
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1228,6 +1228,22 @@ static int rcu_future_gp_cleanup(struct rcu_state *rsp, struct rcu_node *rnp)
 }
 
 /*
+ * Awaken the grace-period kthread for the specified flavor of RCU.
+ * Don't do a self-awaken, and don't bother awakening when there is
+ * nothing for the grace-period kthread to do (as in several CPUs
+ * raced to awaken, and we lost), and finally don't try to awaken
+ * a kthread that has not yet been created.
+ */
+static void rcu_gp_kthread_wake(struct rcu_state *rsp)
+{
+       if (current == rsp->gp_kthread ||
+           !ACCESS_ONCE(rsp->gp_flags) ||
+           !rsp->gp_kthread)
+               return;
+       wake_up(&rsp->gp_wq);
+}
+
+/*
  * If there is room, assign a ->completed number to any callbacks on
  * this CPU that have not already been assigned.  Also accelerate any
  * callbacks that were previously assigned a ->completed number that has
@@ -1670,7 +1686,7 @@ static void rsp_wakeup(struct irq_work *work)
        struct rcu_state *rsp = container_of(work, struct rcu_state, wakeup_work);
 
        /* Wake up rcu_gp_kthread() to start the grace period. */
-       wake_up(&rsp->gp_wq);
+       rcu_gp_kthread_wake(rsp);
 }
 
 /*
@@ -1746,7 +1762,7 @@ static void rcu_report_qs_rsp(struct rcu_state *rsp, unsigned long flags)
 {
        WARN_ON_ONCE(!rcu_gp_in_progress(rsp));
        raw_spin_unlock_irqrestore(&rcu_get_root(rsp)->lock, flags);
-       wake_up(&rsp->gp_wq);  /* Memory barrier implied by wake_up() path. */
+       rcu_gp_kthread_wake(rsp);
 }
 
 /*
@@ -2322,7 +2338,7 @@ static void force_quiescent_state(struct rcu_state *rsp)
        }
        rsp->gp_flags |= RCU_GP_FLAG_FQS;
        raw_spin_unlock_irqrestore(&rnp_old->lock, flags);
-       wake_up(&rsp->gp_wq);  /* Memory barrier implied by wake_up() path. */
+       rcu_gp_kthread_wake(rsp);
 }
 
 /*