linux-kernel - [PATCH v1 3/5] iio:accel:mxc4005: rearrange iio trigger get and register

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Message-ID: <20220523164159.11579-4-ddrokosov@sberdevices.ru>
Date:   Mon, 23 May 2022 16:41:48 +0000
From:   Dmitry Rokosov <DDRokosov@...rdevices.ru>
To:     "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "jic23@...nel.org" <jic23@...nel.org>,
        "lars@...afoo.de" <lars@...afoo.de>,
        "andy.shevchenko@...il.com" <andy.shevchenko@...il.com>,
        "lorenzo.bianconi83@...il.com" <lorenzo.bianconi83@...il.com>,
        "linus.walleij@...aro.org" <linus.walleij@...aro.org>,
        "stephan@...hold.net" <stephan@...hold.net>,
        "hdegoede@...hat.com" <hdegoede@...hat.com>,
        "antoniu.miclaus@...log.com" <antoniu.miclaus@...log.com>,
        "sean@...nix.com" <sean@...nix.com>,
        "linmq006@...il.com" <linmq006@...il.com>,
        "gwendal@...omium.org" <gwendal@...omium.org>,
        "yangyingliang@...wei.com" <yangyingliang@...wei.com>
CC:     "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        kernel <kernel@...rdevices.ru>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Dmitry Rokosov <DDRokosov@...rdevices.ru>
Subject: [PATCH v1 3/5] iio:accel:mxc4005: rearrange iio trigger get and
 register

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
callbacks or rmmod) will derefence "default" module refcnt, which is
completely incorrect.

Signed-off-by: Dmitry Rokosov <ddrokosov@...rdevices.ru>
---
 drivers/iio/accel/mxc4005.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/accel/mxc4005.c b/drivers/iio/accel/mxc4005.c
index b3afbf064915..df600d2917c0 100644
--- a/drivers/iio/accel/mxc4005.c
+++ b/drivers/iio/accel/mxc4005.c
@@ -456,8 +456,6 @@ static int mxc4005_probe(struct i2c_client *client,
 
 		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) {
@@ -465,6 +463,8 @@ static int mxc4005_probe(struct i2c_client *client,
 				"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);
-- 
2.36.0