linux-kernel - [tip: core/rcu] rcu/tree: Move kfree_rcu_cpu locking/unlocking to separate functions

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Date:   Fri, 31 Jul 2020 09:23:21 -0000
From:   "tip-bot2 for Uladzislau Rezki (Sony)" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Joel Fernandes (Google)" <joel@...lfernandes.org>,
        "Uladzislau Rezki (Sony)" <urezki@...il.com>,
        "Paul E. McKenney" <paulmck@...nel.org>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: core/rcu] rcu/tree: Move kfree_rcu_cpu locking/unlocking to
 separate functions

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     952371d6fc0bc360d1d5780f86bb355836117ca2
Gitweb:        https://git.kernel.org/tip/952371d6fc0bc360d1d5780f86bb355836117ca2
Author:        Uladzislau Rezki (Sony) <urezki@...il.com>
AuthorDate:    Mon, 25 May 2020 23:47:50 +02:00
Committer:     Paul E. McKenney <paulmck@...nel.org>
CommitterDate: Mon, 29 Jun 2020 11:59:25 -07:00

rcu/tree: Move kfree_rcu_cpu locking/unlocking to separate functions

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@...lfernandes.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 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 bcdc063..368bdc4 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3035,6 +3035,27 @@ 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.
@@ -3260,11 +3281,7 @@ 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.
@@ -3295,9 +3312,7 @@ 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);