iio: core: move 'mlock' to 'struct iio_dev_opaque'

Now that there are no more users accessing 'mlock' directly, we can move
it to the iio_dev private structure. Hence, it's now explicit that new
driver's should not directly use this lock.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20221012151620.1725215-5-nuno.sa@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

7 files changed, 42 insertions, 37 deletions

diff --git a/drivers/iio/TODO b/drivers/iio/TODO
index 7d7326b7085a..2ace27d1ac62 100644
--- a/drivers/iio/TODO
+++ b/drivers/iio/TODO
@@ -7,9 +7,6 @@ tree
   - ABI Documentation
   - Audit driviers/iio/staging/Documentation
 
-- Replace iio_dev->mlock by either a local lock or use
-iio_claim_direct.(Requires analysis of the purpose of the lock.)
-
 - Converting drivers from device tree centric to more generic
 property handlers.
 
diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 228598b82a2f..9cd7db549fcb 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -507,13 +507,14 @@ static ssize_t iio_scan_el_store(struct device *dev,
 	int ret;
 	bool state;
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 	struct iio_buffer *buffer = this_attr->buffer;
 
 	ret = kstrtobool(buf, &state);
 	if (ret < 0)
 		return ret;
-	mutex_lock(&indio_dev->mlock);
+	mutex_lock(&iio_dev_opaque->mlock);
 	if (iio_buffer_is_active(buffer)) {
 		ret = -EBUSY;
 		goto error_ret;
@@ -532,7 +533,7 @@ static ssize_t iio_scan_el_store(struct device *dev,
 	}
 
 error_ret:
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&iio_dev_opaque->mlock);
 
 	return ret < 0 ? ret : len;
 
@@ -554,6 +555,7 @@ static ssize_t iio_scan_el_ts_store(struct device *dev,
 {
 	int ret;
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
 	bool state;
 
@@ -561,14 +563,14 @@ static ssize_t iio_scan_el_ts_store(struct device *dev,
 	if (ret < 0)
 		return ret;
 
-	mutex_lock(&indio_dev->mlock);
+	mutex_lock(&iio_dev_opaque->mlock);
 	if (iio_buffer_is_active(buffer)) {
 		ret = -EBUSY;
 		goto error_ret;
 	}
 	buffer->scan_timestamp = state;
 error_ret:
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&iio_dev_opaque->mlock);
 
 	return ret ? ret : len;
 }
@@ -642,6 +644,7 @@ static ssize_t length_store(struct device *dev, struct device_attribute *attr,
 			    const char *buf, size_t len)
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
 	unsigned int val;
 	int ret;
@@ -653,7 +656,7 @@ static ssize_t length_store(struct device *dev, struct device_attribute *attr,
 	if (val == buffer->length)
 		return len;
 
-	mutex_lock(&indio_dev->mlock);
+	mutex_lock(&iio_dev_opaque->mlock);
 	if (iio_buffer_is_active(buffer)) {
 		ret = -EBUSY;
 	} else {
@@ -665,7 +668,7 @@ static ssize_t length_store(struct device *dev, struct device_attribute *attr,
 	if (buffer->length && buffer->length < buffer->watermark)
 		buffer->watermark = buffer->length;
 out:
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&iio_dev_opaque->mlock);
 
 	return ret ? ret : len;
 }
@@ -1256,7 +1259,7 @@ int iio_update_buffers(struct iio_dev *indio_dev,
 		return -EINVAL;
 
 	mutex_lock(&iio_dev_opaque->info_exist_lock);
-	mutex_lock(&indio_dev->mlock);
+	mutex_lock(&iio_dev_opaque->mlock);
 
 	if (insert_buffer && iio_buffer_is_active(insert_buffer))
 		insert_buffer = NULL;
@@ -1277,7 +1280,7 @@ int iio_update_buffers(struct iio_dev *indio_dev,
 	ret = __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);
 
 out_unlock:
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&iio_dev_opaque->mlock);
 	mutex_unlock(&iio_dev_opaque->info_exist_lock);
 
 	return ret;
@@ -1296,6 +1299,7 @@ static ssize_t enable_store(struct device *dev, struct device_attribute *attr,
 	int ret;
 	bool requested_state;
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
 	bool inlist;
 
@@ -1303,7 +1307,7 @@ static ssize_t enable_store(struct device *dev, struct device_attribute *attr,
 	if (ret < 0)
 		return ret;
 
-	mutex_lock(&indio_dev->mlock);
+	mutex_lock(&iio_dev_opaque->mlock);
 
 	/* Find out if it is in the list */
 	inlist = iio_buffer_is_active(buffer);
@@ -1317,7 +1321,7 @@ static ssize_t enable_store(struct device *dev, struct device_attribute *attr,
 		ret = __iio_update_buffers(indio_dev, NULL, buffer);
 
 done:
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&iio_dev_opaque->mlock);
 	return (ret < 0) ? ret : len;
 }
 
@@ -1334,6 +1338,7 @@ static ssize_t watermark_store(struct device *dev,
 			       const char *buf, size_t len)
 {
 	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 	struct iio_buffer *buffer = to_iio_dev_attr(attr)->buffer;
 	unsigned int val;
 	int ret;
@@ -1344,7 +1349,7 @@ static ssize_t watermark_store(struct device *dev,
 	if (!val)
 		return -EINVAL;
 
-	mutex_lock(&indio_dev->mlock);
+	mutex_lock(&iio_dev_opaque->mlock);
 
 	if (val > buffer->length) {
 		ret = -EINVAL;
@@ -1358,7 +1363,7 @@ static ssize_t watermark_store(struct device *dev,
 
 	buffer->watermark = val;
 out:
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&iio_dev_opaque->mlock);
 
 	return ret ? ret : len;
 }
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index b2b7bd27adc7..52e690f031cb 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -285,16 +285,16 @@ int iio_device_set_clock(struct iio_dev *indio_dev, clockid_t clock_id)
 	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
 	const struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
 
-	ret = mutex_lock_interruptible(&indio_dev->mlock);
+	ret = mutex_lock_interruptible(&iio_dev_opaque->mlock);
 	if (ret)
 		return ret;
 	if ((ev_int && iio_event_enabled(ev_int)) ||
 	    iio_buffer_enabled(indio_dev)) {
-		mutex_unlock(&indio_dev->mlock);
+		mutex_unlock(&iio_dev_opaque->mlock);
 		return -EBUSY;
 	}
 	iio_dev_opaque->clock_id = clock_id;
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&iio_dev_opaque->mlock);
 
 	return 0;
 }
@@ -1674,7 +1674,7 @@ struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv)
 	indio_dev->dev.type = &iio_device_type;
 	indio_dev->dev.bus = &iio_bus_type;
 	device_initialize(&indio_dev->dev);
-	mutex_init(&indio_dev->mlock);
+	mutex_init(&iio_dev_opaque->mlock);
 	mutex_init(&iio_dev_opaque->info_exist_lock);
 	INIT_LIST_HEAD(&iio_dev_opaque->channel_attr_list);
 
@@ -1696,7 +1696,7 @@ struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv)
 	INIT_LIST_HEAD(&iio_dev_opaque->ioctl_handlers);
 
 	lockdep_register_key(&iio_dev_opaque->mlock_key);
-	lockdep_set_class(&indio_dev->mlock, &iio_dev_opaque->mlock_key);
+	lockdep_set_class(&iio_dev_opaque->mlock, &iio_dev_opaque->mlock_key);
 
 	return indio_dev;
 }
@@ -2058,10 +2058,12 @@ EXPORT_SYMBOL_GPL(__devm_iio_device_register);
  */
 int iio_device_claim_direct_mode(struct iio_dev *indio_dev)
 {
-	mutex_lock(&indio_dev->mlock);
+	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
+
+	mutex_lock(&iio_dev_opaque->mlock);
 
 	if (iio_buffer_enabled(indio_dev)) {
-		mutex_unlock(&indio_dev->mlock);
+		mutex_unlock(&iio_dev_opaque->mlock);
 		return -EBUSY;
 	}
 	return 0;
@@ -2079,7 +2081,7 @@ EXPORT_SYMBOL_GPL(iio_device_claim_direct_mode);
  */
 void iio_device_release_direct_mode(struct iio_dev *indio_dev)
 {
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&to_iio_dev_opaque(indio_dev)->mlock);
 }
 EXPORT_SYMBOL_GPL(iio_device_release_direct_mode);
 
@@ -2096,12 +2098,14 @@ EXPORT_SYMBOL_GPL(iio_device_release_direct_mode);
  */
 int iio_device_claim_buffer_mode(struct iio_dev *indio_dev)
 {
-	mutex_lock(&indio_dev->mlock);
+	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
+
+	mutex_lock(&iio_dev_opaque->mlock);
 
 	if (iio_buffer_enabled(indio_dev))
 		return 0;
 
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&iio_dev_opaque->mlock);
 	return -EBUSY;
 }
 EXPORT_SYMBOL_GPL(iio_device_claim_buffer_mode);
@@ -2117,7 +2121,7 @@ EXPORT_SYMBOL_GPL(iio_device_claim_buffer_mode);
  */
 void iio_device_release_buffer_mode(struct iio_dev *indio_dev)
 {
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&to_iio_dev_opaque(indio_dev)->mlock);
 }
 EXPORT_SYMBOL_GPL(iio_device_release_buffer_mode);
 
diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c
index 3d78da2531a9..1a26393a7c0c 100644
--- a/drivers/iio/industrialio-event.c
+++ b/drivers/iio/industrialio-event.c
@@ -198,7 +198,7 @@ static int iio_event_getfd(struct iio_dev *indio_dev)
 	if (ev_int == NULL)
 		return -ENODEV;
 
-	fd = mutex_lock_interruptible(&indio_dev->mlock);
+	fd = mutex_lock_interruptible(&iio_dev_opaque->mlock);
 	if (fd)
 		return fd;
 
@@ -219,7 +219,7 @@ static int iio_event_getfd(struct iio_dev *indio_dev)
 	}
 
 unlock:
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&iio_dev_opaque->mlock);
 	return fd;
 }
 
diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
index 6885a186fe27..a2f3cc2f65ef 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -120,12 +120,12 @@ int iio_trigger_set_immutable(struct iio_dev *indio_dev, struct iio_trigger *tri
 		return -EINVAL;
 
 	iio_dev_opaque = to_iio_dev_opaque(indio_dev);
-	mutex_lock(&indio_dev->mlock);
+	mutex_lock(&iio_dev_opaque->mlock);
 	WARN_ON(iio_dev_opaque->trig_readonly);
 
 	indio_dev->trig = iio_trigger_get(trig);
 	iio_dev_opaque->trig_readonly = true;
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&iio_dev_opaque->mlock);
 
 	return 0;
 }
@@ -438,16 +438,16 @@ static ssize_t current_trigger_store(struct device *dev,
 	struct iio_trigger *trig;
 	int ret;
 
-	mutex_lock(&indio_dev->mlock);
+	mutex_lock(&iio_dev_opaque->mlock);
 	if (iio_dev_opaque->currentmode == INDIO_BUFFER_TRIGGERED) {
-		mutex_unlock(&indio_dev->mlock);
+		mutex_unlock(&iio_dev_opaque->mlock);
 		return -EBUSY;
 	}
 	if (iio_dev_opaque->trig_readonly) {
-		mutex_unlock(&indio_dev->mlock);
+		mutex_unlock(&iio_dev_opaque->mlock);
 		return -EPERM;
 	}
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&iio_dev_opaque->mlock);
 
 	trig = iio_trigger_acquire_by_name(buf);
 	if (oldtrig == trig) {
diff --git a/include/linux/iio/iio-opaque.h b/include/linux/iio/iio-opaque.h
index d1f8b30a7c8b..5aec3945555b 100644
--- a/include/linux/iio/iio-opaque.h
+++ b/include/linux/iio/iio-opaque.h
@@ -11,6 +11,7 @@
  *				checked by device drivers but should be considered
  *				read-only as this is a core internal bit
  * @driver_module:		used to make it harder to undercut users
+ * @mlock:			lock used to prevent simultaneous device state changes
  * @mlock_key:			lockdep class for iio_dev lock
  * @info_exist_lock:		lock to prevent use during removal
  * @trig_readonly:		mark the current trigger immutable
@@ -43,6 +44,7 @@ struct iio_dev_opaque {
 	int				currentmode;
 	int				id;
 	struct module			*driver_module;
+	struct mutex			mlock;
 	struct lock_class_key		mlock_key;
 	struct mutex			info_exist_lock;
 	bool				trig_readonly;
diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index 9d3bd6379eb8..8e0afaaa3f75 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -548,8 +548,6 @@ struct iio_buffer_setup_ops {
  *			and owner
  * @buffer:		[DRIVER] any buffer present
  * @scan_bytes:		[INTERN] num bytes captured to be fed to buffer demux
- * @mlock:		[INTERN] lock used to prevent simultaneous device state
- *			changes
  * @available_scan_masks: [DRIVER] optional array of allowed bitmasks
  * @masklength:		[INTERN] the length of the mask established from
  *			channels
@@ -574,7 +572,6 @@ struct iio_dev {
 
 	struct iio_buffer		*buffer;
 	int				scan_bytes;
-	struct mutex			mlock;
 
 	const unsigned long		*available_scan_masks;
 	unsigned			masklength;