iio: buffer: iio: core: move to the cleanup.h magic

Use the new cleanup magic for handling mutexes in IIO. This allows us to
greatly simplify some code paths.
Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240229-iio-use-cleanup-magic-v3-3-c3d34889ae3c@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/industrialio-buffer.c

@@ -10,6 +10,7 @@
  * - Alternative access techniques?
  */
 #include <linux/anon_inodes.h>
+#include <linux/cleanup.h>
 #include <linux/kernel.h>
 #include <linux/export.h>
 #include <linux/device.h>
@@ -533,28 +534,26 @@ static ssize_t iio_scan_el_store(struct device *dev,
 	ret = kstrtobool(buf, &state);
 	if (ret < 0)
 		return ret;
-	mutex_lock(&iio_dev_opaque->mlock);
-	if (iio_buffer_is_active(buffer)) {
-		ret = -EBUSY;
-		goto error_ret;
-	}
+
+	guard(mutex)(&iio_dev_opaque->mlock);
+	if (iio_buffer_is_active(buffer))
+		return -EBUSY;
+
 	ret = iio_scan_mask_query(indio_dev, buffer, this_attr->address);
 	if (ret < 0)
-		goto error_ret;
-	if (!state && ret) {
-		ret = iio_scan_mask_clear(buffer, this_attr->address);
-		if (ret)
-			goto error_ret;
-	} else if (state && !ret) {
-		ret = iio_scan_mask_set(indio_dev, buffer, this_attr->address);
-		if (ret)
-			goto error_ret;
-	}
+		return ret;
 
-error_ret:
-	mutex_unlock(&iio_dev_opaque->mlock);
+	if (state && ret)
+		return len;
 
-	return ret < 0 ? ret : len;
+	if (state)
+		ret = iio_scan_mask_set(indio_dev, buffer, this_attr->address);
+	else
+		ret = iio_scan_mask_clear(buffer, this_attr->address);
+	if (ret)
+		return ret;
+
+	return len;
 }
 
 static ssize_t iio_scan_el_ts_show(struct device *dev,
@@ -581,16 +580,13 @@ static ssize_t iio_scan_el_ts_store(struct device *dev,
 	if (ret < 0)
 		return ret;
 
-	mutex_lock(&iio_dev_opaque->mlock);
-	if (iio_buffer_is_active(buffer)) {
-		ret = -EBUSY;
-		goto error_ret;
-	}
+	guard(mutex)(&iio_dev_opaque->mlock);
+	if (iio_buffer_is_active(buffer))
+		return -EBUSY;
+
 	buffer->scan_timestamp = state;
-error_ret:
-	mutex_unlock(&iio_dev_opaque->mlock);
 
-	return ret ? ret : len;
+	return len;
 }
 
 static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
@@ -674,21 +670,16 @@ static ssize_t length_store(struct device *dev, struct device_attribute *attr,
 	if (val == buffer->length)
 		return len;
 
-	mutex_lock(&iio_dev_opaque->mlock);
-	if (iio_buffer_is_active(buffer)) {
-		ret = -EBUSY;
-	} else {
-		buffer->access->set_length(buffer, val);
-		ret = 0;
-	}
-	if (ret)
-		goto out;
+	guard(mutex)(&iio_dev_opaque->mlock);
+	if (iio_buffer_is_active(buffer))
+		return -EBUSY;
+
+	buffer->access->set_length(buffer, val);
+
 	if (buffer->length && buffer->length < buffer->watermark)
 		buffer->watermark = buffer->length;
-out:
-	mutex_unlock(&iio_dev_opaque->mlock);
 
-	return ret ? ret : len;
+	return len;
 }
 
 static ssize_t enable_show(struct device *dev, struct device_attribute *attr,
@@ -1268,7 +1259,6 @@ int iio_update_buffers(struct iio_dev *indio_dev,
 		       struct iio_buffer *remove_buffer)
 {
 	struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
-	int ret;
 
 	if (insert_buffer == remove_buffer)
 		return 0;
@@ -1277,8 +1267,8 @@ int iio_update_buffers(struct iio_dev *indio_dev,
 	    insert_buffer->direction == IIO_BUFFER_DIRECTION_OUT)
 		return -EINVAL;
 
-	mutex_lock(&iio_dev_opaque->info_exist_lock);
-	mutex_lock(&iio_dev_opaque->mlock);
+	guard(mutex)(&iio_dev_opaque->info_exist_lock);
+	guard(mutex)(&iio_dev_opaque->mlock);
 
 	if (insert_buffer && iio_buffer_is_active(insert_buffer))
 		insert_buffer = NULL;
@@ -1286,23 +1276,13 @@ int iio_update_buffers(struct iio_dev *indio_dev,
 	if (remove_buffer && !iio_buffer_is_active(remove_buffer))
 		remove_buffer = NULL;
 
-	if (!insert_buffer && !remove_buffer) {
-		ret = 0;
-		goto out_unlock;
-	}
-
-	if (!indio_dev->info) {
-		ret = -ENODEV;
-		goto out_unlock;
-	}
-
-	ret = __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);
+	if (!insert_buffer && !remove_buffer)
+		return 0;
 
-out_unlock:
-	mutex_unlock(&iio_dev_opaque->mlock);
-	mutex_unlock(&iio_dev_opaque->info_exist_lock);
+	if (!indio_dev->info)
+		return -ENODEV;
 
-	return ret;
+	return __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);
 }
 EXPORT_SYMBOL_GPL(iio_update_buffers);
 
@@ -1326,22 +1306,22 @@ static ssize_t enable_store(struct device *dev, struct device_attribute *attr,
 	if (ret < 0)
 		return ret;
 
-	mutex_lock(&iio_dev_opaque->mlock);
+	guard(mutex)(&iio_dev_opaque->mlock);
 
 	/* Find out if it is in the list */
 	inlist = iio_buffer_is_active(buffer);
 	/* Already in desired state */
 	if (inlist == requested_state)
-		goto done;
+		return len;
 
 	if (requested_state)
 		ret = __iio_update_buffers(indio_dev, buffer, NULL);
 	else
 		ret = __iio_update_buffers(indio_dev, NULL, buffer);
+	if (ret)
+		return ret;
 
-done:
-	mutex_unlock(&iio_dev_opaque->mlock);
-	return (ret < 0) ? ret : len;
+	return len;
 }
 
 static ssize_t watermark_show(struct device *dev, struct device_attribute *attr,
@@ -1368,23 +1348,17 @@ static ssize_t watermark_store(struct device *dev,
 	if (!val)
 		return -EINVAL;
 
-	mutex_lock(&iio_dev_opaque->mlock);
+	guard(mutex)(&iio_dev_opaque->mlock);
 
-	if (val > buffer->length) {
-		ret = -EINVAL;
-		goto out;
-	}
+	if (val > buffer->length)
+		return -EINVAL;
 
-	if (iio_buffer_is_active(buffer)) {
-		ret = -EBUSY;
-		goto out;
-	}
+	if (iio_buffer_is_active(buffer))
+		return -EBUSY;
 
 	buffer->watermark = val;
-out:
-	mutex_unlock(&iio_dev_opaque->mlock);
 
-	return ret ? ret : len;
+	return len;
 }
 
 static ssize_t data_available_show(struct device *dev,