linux-kernel - [PATCH 4/8] counter: interrupt-cnt: Use container_of instead of struct counter

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Date:   Tue, 21 Dec 2021 11:45:42 +0100
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Oleksij Rempel <linux@...pel-privat.de>,
        William Breathitt Gray <vilhelm.gray@...il.com>
Cc:     linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 4/8] counter: interrupt-cnt: Use container_of instead of struct counter_device::priv

Using counter->priv is a memory read and so more expensive than
container_of which is only an addition.

So container_of is expected to be a tad faster, it's type-safe, and
produces smaller code (ARCH=arm allmodconfig):

	add/remove: 0/0 grow/shrink: 0/6 up/down: 0/-60 (-60)
	Function                                     old     new   delta
	interrupt_cnt_write                          136     128      -8
	interrupt_cnt_read                            92      84      -8
	interrupt_cnt_enable_write                   180     172      -8
	interrupt_cnt_enable_read                     76      68      -8
	interrupt_cnt_probe                         1048    1036     -12
	interrupt_cnt_signal_read                    164     148     -16
	Total: Before=2841, After=2781, chg -2.11%

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
---
 drivers/counter/interrupt-cnt.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/counter/interrupt-cnt.c b/drivers/counter/interrupt-cnt.c
index 8514a87fcbee..c61628aa5c32 100644
--- a/drivers/counter/interrupt-cnt.c
+++ b/drivers/counter/interrupt-cnt.c
@@ -25,6 +25,11 @@ struct interrupt_cnt_priv {
 	struct counter_count cnts;
 };
 
+static inline struct interrupt_cnt_priv *interrupt_cnt_from_counter(struct counter_device *counter)
+{
+	return container_of(counter, struct interrupt_cnt_priv, counter);
+}
+
 static irqreturn_t interrupt_cnt_isr(int irq, void *dev_id)
 {
 	struct interrupt_cnt_priv *priv = dev_id;
@@ -37,7 +42,7 @@ static irqreturn_t interrupt_cnt_isr(int irq, void *dev_id)
 static int interrupt_cnt_enable_read(struct counter_device *counter,
 				     struct counter_count *count, u8 *enable)
 {
-	struct interrupt_cnt_priv *priv = counter->priv;
+	struct interrupt_cnt_priv *priv = interrupt_cnt_from_counter(counter);
 
 	*enable = priv->enabled;
 
@@ -47,7 +52,7 @@ static int interrupt_cnt_enable_read(struct counter_device *counter,
 static int interrupt_cnt_enable_write(struct counter_device *counter,
 				      struct counter_count *count, u8 enable)
 {
-	struct interrupt_cnt_priv *priv = counter->priv;
+	struct interrupt_cnt_priv *priv = interrupt_cnt_from_counter(counter);
 
 	if (priv->enabled == enable)
 		return 0;
@@ -85,7 +90,7 @@ static int interrupt_cnt_action_read(struct counter_device *counter,
 static int interrupt_cnt_read(struct counter_device *counter,
 			      struct counter_count *count, u64 *val)
 {
-	struct interrupt_cnt_priv *priv = counter->priv;
+	struct interrupt_cnt_priv *priv = interrupt_cnt_from_counter(counter);
 
 	*val = atomic_read(&priv->count);
 
@@ -95,7 +100,7 @@ static int interrupt_cnt_read(struct counter_device *counter,
 static int interrupt_cnt_write(struct counter_device *counter,
 			       struct counter_count *count, const u64 val)
 {
-	struct interrupt_cnt_priv *priv = counter->priv;
+	struct interrupt_cnt_priv *priv = interrupt_cnt_from_counter(counter);
 
 	if (val != (typeof(priv->count.counter))val)
 		return -ERANGE;
@@ -122,7 +127,7 @@ static int interrupt_cnt_signal_read(struct counter_device *counter,
 				     struct counter_signal *signal,
 				     enum counter_signal_level *level)
 {
-	struct interrupt_cnt_priv *priv = counter->priv;
+	struct interrupt_cnt_priv *priv = interrupt_cnt_from_counter(counter);
 	int ret;
 
 	if (!priv->gpio)
@@ -199,7 +204,6 @@ static int interrupt_cnt_probe(struct platform_device *pdev)
 	priv->cnts.ext = interrupt_cnt_ext;
 	priv->cnts.num_ext = ARRAY_SIZE(interrupt_cnt_ext);
 
-	priv->counter.priv = priv;
 	priv->counter.name = dev_name(dev);
 	priv->counter.parent = dev;
 	priv->counter.ops = &interrupt_cnt_ops;
-- 
2.33.0