[PATCH 4.4 050/137] iio: inkern: fix a NULL dereference on error

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <redacted>

commit d81dac3c1c5295c61b15293074ac2bd3254e1875 upstream.

In twl4030_bci_probe() there are some failure paths where we call
iio_channel_release() with a NULL pointer.  (Apparently, that driver can
opperate without a valid channel pointer).  Let's fix it by adding a
NULL check in iio_channel_release().

Fixes: 2202e1fc5a29 ('drivers: power: twl4030_charger: fix link problems when building as module')
Signed-off-by: Dan Carpenter <redacted>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/iio/inkern.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c

@@ -351,6 +351,8 @@ EXPORT_SYMBOL_GPL(iio_channel_get);
 
 void iio_channel_release(struct iio_channel *channel)
 {
+	if (!channel)
+		return;
 	iio_device_put(channel->indio_dev);
 	kfree(channel);
 }