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 <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/TODO

···
   - 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.
 

drivers/iio/industrialio-buffer.c

···
 	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;
···
 	}
 
 error_ret:
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&iio_dev_opaque->mlock);
 
 	return ret < 0 ? ret : len;
 
···
 {
 	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;
 
···
 	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;
 }
···
 			    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;
···
 	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 {
···
 	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;
 }
···
 		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;
···
 	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;
···
 	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;
 
···
 	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);
···
 		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;
 }
 
···
 			       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;
···
 	if (!val)
 		return -EINVAL;
 
-	mutex_lock(&indio_dev->mlock);
+	mutex_lock(&iio_dev_opaque->mlock);
 
 	if (val > buffer->length) {
 		ret = -EINVAL;
···
 
 	buffer->watermark = val;
 out:
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&iio_dev_opaque->mlock);
 
 	return ret ? ret : len;
 }

drivers/iio/industrialio-core.c

···
 	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;
 }
···
 	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);
 
···
 	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;
 }
···
  */
 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;
···
  */
 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);
 
···
  */
 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);
···
  */
 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);
 

drivers/iio/industrialio-event.c

···
 	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;
 
···
 	}
 
 unlock:
-	mutex_unlock(&indio_dev->mlock);
+	mutex_unlock(&iio_dev_opaque->mlock);
 	return fd;
 }
 

drivers/iio/industrialio-trigger.c

···
 		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;
 }
···
 	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) {

include/linux/iio/iio-opaque.h

···
  *				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
···
 	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;

include/linux/iio/iio.h

···
  *			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
···
 
 	struct iio_buffer		*buffer;
 	int				scan_bytes;
-	struct mutex			mlock;
 
 	const unsigned long		*available_scan_masks;
 	unsigned			masklength;