[PATCH tip/core/rcu 07/17] rcu/tree: Move kfree_rcu_cpu locking/unlocking to separate functions

[paulmck]

From: "Uladzislau Rezki (Sony)" <urezki@xxxxxxxxx>

Introduce helpers to lock and unlock per-cpu "kfree_rcu_cpu"
structures. That will make kfree_call_rcu() more readable
and prevent programming errors.

Reviewed-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 kernel/rcu/tree.c | 31 +++++++++++++++++++++++--------
 1 file changed, 23 insertions(+), 8 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 519a3f5..edc512e 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3017,6 +3017,27 @@ debug_rcu_bhead_unqueue(struct kfree_rcu_bulk_data *bhead)
 #endif
 }
 
+static inline struct kfree_rcu_cpu *
+krc_this_cpu_lock(unsigned long *flags)
+{
+	struct kfree_rcu_cpu *krcp;
+
+	local_irq_save(*flags);	// For safely calling this_cpu_ptr().
+	krcp = this_cpu_ptr(&krc);
+	if (likely(krcp->initialized))
+		raw_spin_lock(&krcp->lock);
+
+	return krcp;
+}
+
+static inline void
+krc_this_cpu_unlock(struct kfree_rcu_cpu *krcp, unsigned long flags)
+{
+	if (likely(krcp->initialized))
+		raw_spin_unlock(&krcp->lock);
+	local_irq_restore(flags);
+}
+
 /*
  * This function is invoked in workqueue context after a grace period.
  * It frees all the objects queued on ->bhead_free or ->head_free.
@@ -3242,11 +3263,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
 	struct kfree_rcu_cpu *krcp;
 	void *ptr;
 
-	local_irq_save(flags);	// For safely calling this_cpu_ptr().
-	krcp = this_cpu_ptr(&krc);
-	if (krcp->initialized)
-		raw_spin_lock(&krcp->lock);
-
+	krcp = krc_this_cpu_lock(&flags);
 	ptr = (void *)head - (unsigned long)func;
 
 	// Queue the object but don't yet schedule the batch.
@@ -3277,9 +3294,7 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
 	}
 
 unlock_return:
-	if (krcp->initialized)
-		raw_spin_unlock(&krcp->lock);
-	local_irq_restore(flags);
+	krc_this_cpu_unlock(krcp, flags);
 }
 EXPORT_SYMBOL_GPL(kfree_call_rcu);
 
-- 
2.9.5