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From:   paulmck@kernel.org
To:     rcu@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org,
        jiangshanlai@gmail.com, dipankar@in.ibm.com,
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        fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org,
        "Uladzislau Rezki (Sony)" <urezki@gmail.com>,
        "Paul E . McKenney" <paulmck@kernel.org>
Subject: [PATCH tip/core/rcu 06/17] rcu/tree: Simplify KFREE_BULK_MAX_ENTR macro
Date:   Wed, 24 Jun 2020 13:12:15 -0700
Message-Id: <20200624201226.21197-6-paulmck@kernel.org>
In-Reply-To: <20200624201200.GA28901@paulmck-ThinkPad-P72>
References: <20200624201200.GA28901@paulmck-ThinkPad-P72>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: "Uladzislau Rezki (Sony)" <urezki@gmail.com>

We can simplify KFREE_BULK_MAX_ENTR macro and get rid of
magic numbers which were used to make the structure to be
exactly one page.

Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
 kernel/rcu/tree.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index dc5369a..519a3f5 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2940,13 +2940,6 @@ EXPORT_SYMBOL_GPL(call_rcu);
 #define KFREE_DRAIN_JIFFIES (HZ / 50)
 #define KFREE_N_BATCHES 2
 
-/*
- * This macro defines how many entries the "records" array
- * will contain. It is based on the fact that the size of
- * kfree_rcu_bulk_data structure becomes exactly one page.
- */
-#define KFREE_BULK_MAX_ENTR ((PAGE_SIZE / sizeof(void *)) - 3)
-
 /**
  * struct kfree_rcu_bulk_data - single block to store kfree_rcu() pointers
  * @nr_records: Number of active pointers in the array
@@ -2955,10 +2948,18 @@ EXPORT_SYMBOL_GPL(call_rcu);
  */
 struct kfree_rcu_bulk_data {
 	unsigned long nr_records;
-	void *records[KFREE_BULK_MAX_ENTR];
 	struct kfree_rcu_bulk_data *next;
+	void *records[];
 };
 
+/*
+ * This macro defines how many entries the "records" array
+ * will contain. It is based on the fact that the size of
+ * kfree_rcu_bulk_data structure becomes exactly one page.
+ */
+#define KFREE_BULK_MAX_ENTR \
+	((PAGE_SIZE - sizeof(struct kfree_rcu_bulk_data)) / sizeof(void *))
+
 /**
  * struct kfree_rcu_cpu_work - single batch of kfree_rcu() requests
  * @rcu_work: Let queue_rcu_work() invoke workqueue handler after grace period
-- 
2.9.5