[PATCH 5/7] iio: inkern: copy/release available info from producer

[Matteo Martelli <matteomartelli3@xxxxxxxxx>]

Consumers need to call the read_avail_release_resource after reading the
available info. To call the release with info_exists locked, copy the
available info from the producer and immediately call its release
callback. With this change, users of iio_read_avail_channel_raw() and
iio_read_avail_channel_attribute() must free the copied avail info after
calling them.

Signed-off-by: Matteo Martelli <matteomartelli3@xxxxxxxxx>
---
 drivers/iio/inkern.c         | 64 +++++++++++++++++++++++++++++++++-----------
 include/linux/iio/consumer.h |  4 +--
 2 files changed, 50 insertions(+), 18 deletions(-)

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index 7f325b3ed08fae6674245312cf8f57bb151006c0..cc65ef79451e5aa2cea447e168007a447ffc0d91 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -760,9 +760,25 @@ static int iio_channel_read_avail(struct iio_channel *chan,
 	if (!iio_channel_has_available(chan->channel, info))
 		return -EINVAL;
 
-	if (iio_info->read_avail)
-		return iio_info->read_avail(chan->indio_dev, chan->channel,
-					    vals, type, length, info);
+	if (iio_info->read_avail) {
+		const int *vals_tmp;
+		int ret;
+
+		ret = iio_info->read_avail(chan->indio_dev, chan->channel,
+					   &vals_tmp, type, length, info);
+		if (ret < 0)
+			return ret;
+
+		*vals = kmemdup_array(vals_tmp, *length, sizeof(int), GFP_KERNEL);
+		if (!*vals)
+			return -ENOMEM;
+
+		if (iio_info->read_avail_release_resource)
+			iio_info->read_avail_release_resource(
+				chan->indio_dev, chan->channel, vals_tmp, info);
+
+		return ret;
+	}
 	return -EINVAL;
 }
 
@@ -789,9 +805,11 @@ int iio_read_avail_channel_raw(struct iio_channel *chan,
 	ret = iio_read_avail_channel_attribute(chan, vals, &type, length,
 					       IIO_CHAN_INFO_RAW);
 
-	if (ret >= 0 && type != IIO_VAL_INT)
+	if (ret >= 0 && type != IIO_VAL_INT) {
 		/* raw values are assumed to be IIO_VAL_INT */
+		kfree(*vals);
 		ret = -EINVAL;
+	}
 
 	return ret;
 }
@@ -820,24 +838,31 @@ static int iio_channel_read_max(struct iio_channel *chan,
 			if (val2)
 				*val2 = vals[5];
 		}
-		return 0;
+		ret = 0;
+		break;
 
 	case IIO_AVAIL_LIST:
-		if (length <= 0)
-			return -EINVAL;
+		if (length <= 0) {
+			ret = -EINVAL;
+			goto out;
+		}
 		switch (*type) {
 		case IIO_VAL_INT:
 			*val = max_array(vals, length);
+			ret = 0;
 			break;
 		default:
 			/* TODO: learn about max for other iio values */
-			return -EINVAL;
+			ret = -EINVAL;
 		}
-		return 0;
+		break;
 
 	default:
-		return -EINVAL;
+		ret = -EINVAL;
 	}
+out:
+	kfree(vals);
+	return ret;
 }
 
 int iio_read_max_channel_raw(struct iio_channel *chan, int *val)
@@ -876,24 +901,31 @@ static int iio_channel_read_min(struct iio_channel *chan,
 			if (val2)
 				*val2 = vals[1];
 		}
-		return 0;
+		ret = 0;
+		break;
 
 	case IIO_AVAIL_LIST:
-		if (length <= 0)
-			return -EINVAL;
+		if (length <= 0) {
+			ret = -EINVAL;
+			goto out;
+		}
 		switch (*type) {
 		case IIO_VAL_INT:
 			*val = min_array(vals, length);
+			ret = 0;
 			break;
 		default:
 			/* TODO: learn about min for other iio values */
-			return -EINVAL;
+			ret = -EINVAL;
 		}
-		return 0;
+		break;
 
 	default:
-		return -EINVAL;
+		ret = -EINVAL;
 	}
+out:
+	kfree(vals);
+	return ret;
 }
 
 int iio_read_min_channel_raw(struct iio_channel *chan, int *val)
diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
index 333d1d8ccb37f387fe531577ac5e0bfc7f752cec..e3e268d2574b3e01c9412449d90d627de7efcd84 100644
--- a/include/linux/iio/consumer.h
+++ b/include/linux/iio/consumer.h
@@ -316,7 +316,7 @@ int iio_read_min_channel_raw(struct iio_channel *chan, int *val);
 /**
  * iio_read_avail_channel_raw() - read available raw values from a given channel
  * @chan:		The channel being queried.
- * @vals:		Available values read back.
+ * @vals:		Available values read back. Must be freed after use.
  * @length:		Number of entries in vals.
  *
  * Returns an error code, IIO_AVAIL_RANGE or IIO_AVAIL_LIST.
@@ -334,7 +334,7 @@ int iio_read_avail_channel_raw(struct iio_channel *chan,
 /**
  * iio_read_avail_channel_attribute() - read available channel attribute values
  * @chan:		The channel being queried.
- * @vals:		Available values read back.
+ * @vals:		Available values read back. Must be freed after use.
  * @type:		Type of values read back.
  * @length:		Number of entries in vals.
  * @attribute:		info attribute to be read back.

-- 
2.46.2