iio: Add a helper to free a list of IIO device attributes

We have the same code to free a IIO device attribute list in multiple place.
This patch adds a new helper function to take care of this and replaces the
custom instances with a call to the helper function. Note that we do not need to
call list_del() for each of the list items since we will never look at any of
the list items nor the list itself again.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/iio_core.h

@@ -33,6 +33,7 @@ int __iio_add_chan_devattr(const char *postfix,
 			   enum iio_shared_by shared_by,
 			   struct device *dev,
 			   struct list_head *attr_list);
+void iio_free_chan_devattr_list(struct list_head *attr_list);
 
 /* Event interface flags */
 #define IIO_BUSY_BIT_POS 1

drivers/iio/industrialio-buffer.c

@@ -274,23 +274,6 @@ static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
 	return ret;
 }
 
-static void iio_buffer_remove_and_free_scan_dev_attr(struct iio_dev *indio_dev,
-						     struct iio_dev_attr *p)
-{
-	kfree(p->dev_attr.attr.name);
-	kfree(p);
-}
-
-static void __iio_buffer_attr_cleanup(struct iio_dev *indio_dev)
-{
-	struct iio_dev_attr *p, *n;
-	struct iio_buffer *buffer = indio_dev->buffer;
-
-	list_for_each_entry_safe(p, n,
-				 &buffer->scan_el_dev_attr_list, l)
-		iio_buffer_remove_and_free_scan_dev_attr(indio_dev, p);
-}
-
 static const char * const iio_scan_elements_group_name = "scan_elements";
 
 int iio_buffer_register(struct iio_dev *indio_dev,
@@ -367,7 +350,7 @@ int iio_buffer_register(struct iio_dev *indio_dev,
 error_free_scan_mask:
 	kfree(buffer->scan_mask);
 error_cleanup_dynamic:
-	__iio_buffer_attr_cleanup(indio_dev);
+	iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
 
 	return ret;
 }
@@ -377,7 +360,7 @@ void iio_buffer_unregister(struct iio_dev *indio_dev)
 {
 	kfree(indio_dev->buffer->scan_mask);
 	kfree(indio_dev->buffer->scan_el_group.attrs);
-	__iio_buffer_attr_cleanup(indio_dev);
+	iio_free_chan_devattr_list(&indio_dev->buffer->scan_el_dev_attr_list);
 }
 EXPORT_SYMBOL(iio_buffer_unregister);
 

drivers/iio/industrialio-core.c

@@ -794,11 +794,22 @@ static int iio_device_add_channel_sysfs(struct iio_dev *indio_dev,
 	return attrcount;
 }
 
-static void iio_device_remove_and_free_read_attr(struct iio_dev *indio_dev,
-						 struct iio_dev_attr *p)
+/**
+ * iio_free_chan_devattr_list() - Free a list of IIO device attributes
+ * @attr_list: List of IIO device attributes
+ *
+ * This function frees the memory allocated for each of the IIO device
+ * attributes in the list. Note: if you want to reuse the list after calling
+ * this function you have to reinitialize it using INIT_LIST_HEAD().
+ */
+void iio_free_chan_devattr_list(struct list_head *attr_list)
 {
+	struct iio_dev_attr *p, *n;
+
+	list_for_each_entry_safe(p, n, attr_list, l) {
 		kfree(p->dev_attr.attr.name);
 		kfree(p);
+	}
 }
 
 static ssize_t iio_show_dev_name(struct device *dev,
@@ -814,7 +825,7 @@ static DEVICE_ATTR(name, S_IRUGO, iio_show_dev_name, NULL);
 static int iio_device_register_sysfs(struct iio_dev *indio_dev)
 {
 	int i, ret = 0, attrcount, attrn, attrcount_orig = 0;
-	struct iio_dev_attr *p, *n;
+	struct iio_dev_attr *p;
 	struct attribute **attr;
 
 	/* First count elements in any existing group */
@@ -867,11 +878,7 @@ static int iio_device_register_sysfs(struct iio_dev *indio_dev)
 	return 0;
 
 error_clear_attrs:
-	list_for_each_entry_safe(p, n,
-				 &indio_dev->channel_attr_list, l) {
-		list_del(&p->l);
-		iio_device_remove_and_free_read_attr(indio_dev, p);
-	}
+	iio_free_chan_devattr_list(&indio_dev->channel_attr_list);
 
 	return ret;
 }
@@ -879,12 +886,7 @@ static int iio_device_register_sysfs(struct iio_dev *indio_dev)
 static void iio_device_unregister_sysfs(struct iio_dev *indio_dev)
 {
 
-	struct iio_dev_attr *p, *n;
-
-	list_for_each_entry_safe(p, n, &indio_dev->channel_attr_list, l) {
-		list_del(&p->l);
-		iio_device_remove_and_free_read_attr(indio_dev, p);
-	}
+	iio_free_chan_devattr_list(&indio_dev->channel_attr_list);
 	kfree(indio_dev->chan_attr_group.attrs);
 }
 

drivers/iio/industrialio-event.c

@@ -350,17 +350,6 @@ static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
 	return ret;
 }
 
-static inline void __iio_remove_event_config_attrs(struct iio_dev *indio_dev)
-{
-	struct iio_dev_attr *p, *n;
-	list_for_each_entry_safe(p, n,
-				 &indio_dev->event_interface->
-				 dev_attr_list, l) {
-		kfree(p->dev_attr.attr.name);
-		kfree(p);
-	}
-}
-
 static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
 {
 	int j, ret, attrcount = 0;
@@ -452,7 +441,7 @@ int iio_device_register_eventset(struct iio_dev *indio_dev)
 	return 0;
 
 error_free_setup_event_lines:
-	__iio_remove_event_config_attrs(indio_dev);
+	iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
 	kfree(indio_dev->event_interface);
 error_ret:
 
@@ -477,7 +466,7 @@ void iio_device_unregister_eventset(struct iio_dev *indio_dev)
 {
 	if (indio_dev->event_interface == NULL)
 		return;
-	__iio_remove_event_config_attrs(indio_dev);
+	iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
 	kfree(indio_dev->event_interface->group.attrs);
 	kfree(indio_dev->event_interface);
 }