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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dmitry Rokosov <ddrokosov@sberdevices.ru>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Stable@vger.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>
Subject: [PATCH 5.4 40/60] iio:accel:mxc4005: rearrange iio trigger get and register
Date:   Mon, 27 Jun 2022 13:21:51 +0200
Message-Id: <20220627111928.869433949@linuxfoundation.org>
In-Reply-To: <20220627111927.641837068@linuxfoundation.org>
References: <20220627111927.641837068@linuxfoundation.org>
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From: Dmitry Rokosov <DDRokosov@sberdevices.ru>

commit 9354c224c9b4f55847a0de3e968cba2ebf15af3b upstream.

IIO trigger interface function iio_trigger_get() should be called after
iio_trigger_register() (or its devm analogue) strictly, because of
iio_trigger_get() acquires module refcnt based on the trigger->owner
pointer, which is initialized inside iio_trigger_register() to
THIS_MODULE.
If this call order is wrong, the next iio_trigger_put() (from sysfs
callback or "delete module" path) will dereference "default" module
refcnt, which is incorrect behaviour.

Fixes: 47196620c82f ("iio: mxc4005: add data ready trigger for mxc4005")
Signed-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220524181150.9240-4-ddrokosov@sberdevices.ru
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/iio/accel/mxc4005.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/iio/accel/mxc4005.c
+++ b/drivers/iio/accel/mxc4005.c
@@ -462,8 +462,6 @@ static int mxc4005_probe(struct i2c_clie
 		data->dready_trig->dev.parent = &client->dev;
 		data->dready_trig->ops = &mxc4005_trigger_ops;
 		iio_trigger_set_drvdata(data->dready_trig, indio_dev);
-		indio_dev->trig = data->dready_trig;
-		iio_trigger_get(indio_dev->trig);
 		ret = devm_iio_trigger_register(&client->dev,
 						data->dready_trig);
 		if (ret) {
@@ -471,6 +469,8 @@ static int mxc4005_probe(struct i2c_clie
 				"failed to register trigger\n");
 			return ret;
 		}
+
+		indio_dev->trig = iio_trigger_get(data->dready_trig);
 	}
 
 	return devm_iio_device_register(&client->dev, indio_dev);