iio: inkern: clean up error return code

 When the IIO consumer tries to get specific IIO channel,
 few error cases can be happened.
 (a) Memory allocation failure
 (b) No matched ADC channel error
 (c) Invalid input arguments
 This patch enables cleaning up error handling in case of (a) and (b).

 In error handling code,
 (a): the reference count of the IIO device should be decreased.
 (b): the allocated memory should be freed with restoring the reference count.
 Therefore iio_deivce_put() is called in both cases.
 This can be handled in the last error statement.

 Additionally, integer variable is used for stating each error case explicitly.
 Then, the error returns as ERR_PTR() with this value.
Signed-off-by: NMilo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>

drivers/iio/inkern.c

@@ -111,6 +111,7 @@ struct iio_channel *iio_channel_get(const char *name, const char *channel_name)
 {
 	struct iio_map_internal *c_i = NULL, *c = NULL;
 	struct iio_channel *channel;
+	int err;
 
 	if (name == NULL && channel_name == NULL)
 		return ERR_PTR(-ENODEV);
@@ -131,8 +132,10 @@ struct iio_channel *iio_channel_get(const char *name, const char *channel_name)
 		return ERR_PTR(-ENODEV);
 
 	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
-	if (channel == NULL)
+	if (channel == NULL) {
+		err = -ENOMEM;
 		goto error_no_mem;
+	}
 
 	channel->indio_dev = c->indio_dev;
 
@@ -141,19 +144,19 @@ struct iio_channel *iio_channel_get(const char *name, const char *channel_name)
 			iio_chan_spec_from_name(channel->indio_dev,
 						c->map->adc_channel_label);
 
-		if (channel->channel == NULL)
+		if (channel->channel == NULL) {
+			err = -EINVAL;
 			goto error_no_chan;
+		}
 	}
 
 	return channel;
 
 error_no_chan:
-	iio_device_put(c->indio_dev);
 	kfree(channel);
-	return ERR_PTR(-EINVAL);
 error_no_mem:
 	iio_device_put(c->indio_dev);
-	return ERR_PTR(-ENOMEM);
+	return ERR_PTR(err);
 }
 EXPORT_SYMBOL_GPL(iio_channel_get);