[RFC 05/10] media: v4l: async: Clean testing for duplicated async subdevs

[Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>]

There's a need to verify that a single async sub-device isn't being added
multiple times, this would be an error. This takes place at the time of
adding the async sub-device to the notifier's list as well as when the
notifier is added to the global notifier's list.

Use the pointer to the sub-device for testing this instead of an index to an
array that is long gone.

Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
---
 drivers/media/v4l2-core/v4l2-async.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
index bb78e3618ab5..f554dc8c95c1 100644
--- a/drivers/media/v4l2-core/v4l2-async.c
+++ b/drivers/media/v4l2-core/v4l2-async.c
@@ -456,12 +456,11 @@ __v4l2_async_nf_has_async_subdev(struct v4l2_async_notifier *notifier,
 
 /*
  * Find out whether an async sub-device was set up already or
- * whether it exists in a given notifier before @this_index.
- * If @this_index < 0, search the notifier's entire @asd_list.
+ * whether it exists in a given notifier.
  */
 static bool
 v4l2_async_nf_has_async_subdev(struct v4l2_async_notifier *notifier,
-			       struct v4l2_async_subdev *asd, int this_index)
+			       struct v4l2_async_subdev *asd, bool skip_self)
 {
 	struct v4l2_async_subdev *asd_y;
 	int j = 0;
@@ -470,7 +469,7 @@ v4l2_async_nf_has_async_subdev(struct v4l2_async_notifier *notifier,
 
 	/* Check that an asd is not being added more than once. */
 	list_for_each_entry(asd_y, &notifier->asd_list, asd_list) {
-		if (this_index >= 0 && j++ >= this_index)
+		if (asd == asd_y)
 			break;
 		if (asd_equal(asd, asd_y))
 			return true;
@@ -486,7 +485,7 @@ v4l2_async_nf_has_async_subdev(struct v4l2_async_notifier *notifier,
 
 static int v4l2_async_nf_asd_valid(struct v4l2_async_notifier *notifier,
 				   struct v4l2_async_subdev *asd,
-				   int this_index)
+				   bool skip_self)
 {
 	struct device *dev =
 		notifier->v4l2_dev ? notifier->v4l2_dev->dev : NULL;
@@ -497,7 +496,7 @@ static int v4l2_async_nf_asd_valid(struct v4l2_async_notifier *notifier,
 	switch (asd->match.type) {
 	case V4L2_ASYNC_MATCH_I2C:
 	case V4L2_ASYNC_MATCH_FWNODE:
-		if (v4l2_async_nf_has_async_subdev(notifier, asd, this_index)) {
+		if (v4l2_async_nf_has_async_subdev(notifier, asd, skip_self)) {
 			dev_dbg(dev, "subdev descriptor already listed in this or other notifiers\n");
 			return -EEXIST;
 		}
@@ -520,7 +519,7 @@ EXPORT_SYMBOL(v4l2_async_nf_init);
 static int __v4l2_async_nf_register(struct v4l2_async_notifier *notifier)
 {
 	struct v4l2_async_subdev *asd;
-	int ret, i = 0;
+	int ret;
 
 	INIT_LIST_HEAD(&notifier->waiting);
 	INIT_LIST_HEAD(&notifier->done);
@@ -528,7 +527,7 @@ static int __v4l2_async_nf_register(struct v4l2_async_notifier *notifier)
 	mutex_lock(&list_lock);
 
 	list_for_each_entry(asd, &notifier->asd_list, asd_list) {
-		ret = v4l2_async_nf_asd_valid(notifier, asd, i++);
+		ret = v4l2_async_nf_asd_valid(notifier, asd, true);
 		if (ret)
 			goto err_unlock;
 
@@ -661,7 +660,7 @@ int __v4l2_async_nf_add_subdev(struct v4l2_async_notifier *notifier,
 
 	mutex_lock(&list_lock);
 
-	ret = v4l2_async_nf_asd_valid(notifier, asd, -1);
+	ret = v4l2_async_nf_asd_valid(notifier, asd, false);
 	if (ret)
 		goto unlock;
 
-- 
2.30.2