linux-kernel - [PATCH 07/24] rcu/tree: move locking/unlocking to separate functions

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Message-Id: <20200428205903.61704-8-urezki@gmail.com>
Date:   Tue, 28 Apr 2020 22:58:46 +0200
From:   "Uladzislau Rezki (Sony)" <urezki@...il.com>
To:     LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        "Theodore Y . Ts'o" <tytso@....edu>,
        Matthew Wilcox <willy@...radead.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        RCU <rcu@...r.kernel.org>, Uladzislau Rezki <urezki@...il.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>
Subject: [PATCH 07/24] rcu/tree: move locking/unlocking to separate functions

Introduce two helpers to lock and unlock an access to the
per-cpu "kfree_rcu_cpu" structure. The reason is to make
kfree_call_rcu() function to be more readable.

Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
---
 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 eebd7f627794..bc6c2bc8fa32 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2925,6 +2925,27 @@ 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.
@@ -3150,11 +3171,7 @@ 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. */
@@ -3185,9 +3202,7 @@ 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);
 
-- 
2.20.1