iio: ad7768-1: Call iio_trigger_notify_done() on error

stable inclusion
from stable-v5.10.85
commit c10c53419d8d723aa575f1ebbf5ce492b15e31fc
bugzilla: 186032 https://gitee.com/openeuler/kernel/issues/I4QVI4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c10c53419d8d723aa575f1ebbf5ce492b15e31fc

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

commit 66611464 upstream.

IIO trigger handlers must call iio_trigger_notify_done() when done. This
must be done even when an error occurred. Otherwise the trigger will be
seen as busy indefinitely and the trigger handler will never be called
again.

The ad7768-1 driver neglects to call iio_trigger_notify_done() when there
is an error reading the converter data. Fix this by making sure that
iio_trigger_notify_done() is included in the error exit path.

Fixes: a5f8c7da ("iio: adc: Add AD7768-1 ADC basic support")
Signed-off-by: NLars-Peter Clausen <lars@metafoo.de>
Link: https://lore.kernel.org/r/20211101144055.13858-2-lars@metafoo.de
Cc: <Stable@vger.kernel.org>
Signed-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/iio/adc/ad7768-1.c

@@ -470,8 +470,8 @@ static irqreturn_t ad7768_trigger_handler(int irq, void *p)
 	iio_push_to_buffers_with_timestamp(indio_dev, &st->data.scan,
 					   iio_get_time_ns(indio_dev));
 
-	iio_trigger_notify_done(indio_dev->trig);
 err_unlock:
+	iio_trigger_notify_done(indio_dev->trig);
 	mutex_unlock(&st->lock);
 
 	return IRQ_HANDLED;