linux-kernel - [PATCH v7] iio: adc: max1363: replace uses of mlock

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Date:   Sun, 15 Mar 2020 21:34:58 +0530
From:   Rohit Sarkar <rohitsarkar5398@...il.com>
To:     linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     jic23@...nel.org, dragos.bogdan@...log.com
Subject: [PATCH v7] iio: adc: max1363: replace uses of mlock

Replace usage indio_dev's mlock with either local lock or
iio_device_claim_direct_mode.

Signed-off-by: Rohit Sarkar <rohitsarkar5398@...il.com>
---
Changelog v6 -> v7
* Fix failure handling logic

Changelog v5 -> v6
* Minor failure handling fixes

Changelog v4 -> v5
* Use local lock too at places where driver state needs to be protected.

Changelog v3 -> v4
* Fix indentation

Changelog v2 -> v3
* use iio_device_claim_direct when switching modes
* replace mlock usage in max1363_write_event_config

Changelog v1 -> v2
* Fix indentation

 drivers/iio/adc/max1363.c | 37 ++++++++++++++++++++++++++++---------
 1 file changed, 28 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/adc/max1363.c b/drivers/iio/adc/max1363.c
index 5c2cc61b666e..12d72bf3f12a 100644
--- a/drivers/iio/adc/max1363.c
+++ b/drivers/iio/adc/max1363.c
@@ -150,6 +150,7 @@ struct max1363_chip_info {
  * @current_mode:	the scan mode of this chip
  * @requestedmask:	a valid requested set of channels
  * @reg:		supply regulator
+ * @lock		lock to ensure state is consistent
  * @monitor_on:		whether monitor mode is enabled
  * @monitor_speed:	parameter corresponding to device monitor speed setting
  * @mask_high:		bitmask for enabled high thresholds
@@ -169,6 +170,7 @@ struct max1363_state {
 	const struct max1363_mode	*current_mode;
 	u32				requestedmask;
 	struct regulator		*reg;
+	struct mutex			lock;
 
 	/* Using monitor modes and buffer at the same time is
 	   currently not supported */
@@ -364,7 +366,13 @@ static int max1363_read_single_chan(struct iio_dev *indio_dev,
 	struct max1363_state *st = iio_priv(indio_dev);
 	struct i2c_client *client = st->client;
 
-	mutex_lock(&indio_dev->mlock);
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
+	mutex_lock(&st->lock);
+
+	if (ret < 0)
+		goto error_ret;
 	/*
 	 * If monitor mode is enabled, the method for reading a single
 	 * channel will have to be rather different and has not yet
@@ -372,7 +380,7 @@ static int max1363_read_single_chan(struct iio_dev *indio_dev,
 	 *
 	 * Also, cannot read directly if buffered capture enabled.
 	 */
-	if (st->monitor_on || iio_buffer_enabled(indio_dev)) {
+	if (st->monitor_on) {
 		ret = -EBUSY;
 		goto error_ret;
 	}
@@ -404,8 +412,10 @@ static int max1363_read_single_chan(struct iio_dev *indio_dev,
 		data = rxbuf[0];
 	}
 	*val = data;
+
 error_ret:
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&st->lock);
+	iio_device_release_direct_mode(indio_dev);
 	return ret;
 
 }
@@ -705,9 +715,9 @@ static ssize_t max1363_monitor_store_freq(struct device *dev,
 	if (!found)
 		return -EINVAL;
 
-	mutex_lock(&indio_dev->mlock);
+	mutex_lock(&st->lock);
 	st->monitor_speed = i;
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&st->lock);
 
 	return 0;
 }
@@ -810,12 +820,12 @@ static int max1363_read_event_config(struct iio_dev *indio_dev,
 	int val;
 	int number = chan->channel;
 
-	mutex_lock(&indio_dev->mlock);
+	mutex_lock(&st->lock);
 	if (dir == IIO_EV_DIR_FALLING)
 		val = (1 << number) & st->mask_low;
 	else
 		val = (1 << number) & st->mask_high;
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&st->lock);
 
 	return val;
 }
@@ -962,7 +972,14 @@ static int max1363_write_event_config(struct iio_dev *indio_dev,
 	u16 unifiedmask;
 	int number = chan->channel;
 
-	mutex_lock(&indio_dev->mlock);
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
+	mutex_lock(&st->lock);
+
+	if (ret < 0)
+		goto error_ret;
+
 	unifiedmask = st->mask_low | st->mask_high;
 	if (dir == IIO_EV_DIR_FALLING) {
 
@@ -989,7 +1006,8 @@ static int max1363_write_event_config(struct iio_dev *indio_dev,
 
 	max1363_monitor_mode_update(st, !!(st->mask_high | st->mask_low));
 error_ret:
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&st->lock);
+	iio_device_release_direct_mode(indio_dev);
 
 	return ret;
 }
@@ -1587,6 +1605,7 @@ static int max1363_probe(struct i2c_client *client,
 
 	st = iio_priv(indio_dev);
 
+	mutex_init(&st->lock);
 	st->reg = devm_regulator_get(&client->dev, "vcc");
 	if (IS_ERR(st->reg)) {
 		ret = PTR_ERR(st->reg);
-- 
2.23.0.385.gbc12974a89