linux-kernel - [PATCH v2 4/5] iio:chemical:ccs811: rearrange iio trigger get and register

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Message-ID: <20220524181150.9240-5-ddrokosov@sberdevices.ru>
Date:   Tue, 24 May 2022 18:14:45 +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>,
        "srinivas.pandruvada@...ux.intel.com" 
        <srinivas.pandruvada@...ux.intel.com>,
        "teodora.baluta@...el.com" <teodora.baluta@...el.com>,
        "narcisaanamaria12@...il.com" <narcisaanamaria12@...il.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 v2 4/5] iio:chemical:ccs811: 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
callback or "delete module" path) will dereference "default" module
refcnt, which is incorrect behaviour.

Fixes: f1f065d7ac30 ("iio: chemical: ccs811: Add support for data ready trigger")
Signed-off-by: Dmitry Rokosov <ddrokosov@...rdevices.ru>
---
 drivers/iio/chemical/ccs811.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/chemical/ccs811.c b/drivers/iio/chemical/ccs811.c
index 847194fa1e46..80ef1aa9aae3 100644
--- a/drivers/iio/chemical/ccs811.c
+++ b/drivers/iio/chemical/ccs811.c
@@ -499,11 +499,11 @@ static int ccs811_probe(struct i2c_client *client,
 
 		data->drdy_trig->ops = &ccs811_trigger_ops;
 		iio_trigger_set_drvdata(data->drdy_trig, indio_dev);
-		indio_dev->trig = data->drdy_trig;
-		iio_trigger_get(indio_dev->trig);
 		ret = iio_trigger_register(data->drdy_trig);
 		if (ret)
 			goto err_poweroff;
+
+		indio_dev->trig = iio_trigger_get(data->drdy_trig);
 	}
 
 	ret = iio_triggered_buffer_setup(indio_dev, NULL,
-- 
2.36.0