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[v2,5/5] iio:humidity:hts221: rearrange iio trigger get and register

Message ID 20220524181150.9240-6-ddrokosov@sberdevices.ru (mailing list archive)
State Accepted
Headers show
Series iio: treewide: rearrange iio trig get/register | expand

Commit Message

Dmitry Rokosov May 24, 2022, 6:14 p.m. UTC
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: e4a70e3e7d84 ("iio: humidity: add support to hts221 rh/temp combo device")
Signed-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru>
---
 drivers/iio/humidity/hts221_buffer.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Andy Shevchenko May 24, 2022, 7:52 p.m. UTC | #1
On Tue, May 24, 2022 at 8:14 PM Dmitry Rokosov <DDRokosov@sberdevices.ru> wrote:
>
> 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.

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> Fixes: e4a70e3e7d84 ("iio: humidity: add support to hts221 rh/temp combo device")
> Signed-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru>
> ---
>  drivers/iio/humidity/hts221_buffer.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iio/humidity/hts221_buffer.c b/drivers/iio/humidity/hts221_buffer.c
> index f29692b9d2db..66b32413cf5e 100644
> --- a/drivers/iio/humidity/hts221_buffer.c
> +++ b/drivers/iio/humidity/hts221_buffer.c
> @@ -135,9 +135,12 @@ int hts221_allocate_trigger(struct iio_dev *iio_dev)
>
>         iio_trigger_set_drvdata(hw->trig, iio_dev);
>         hw->trig->ops = &hts221_trigger_ops;
> +
> +       err = devm_iio_trigger_register(hw->dev, hw->trig);
> +
>         iio_dev->trig = iio_trigger_get(hw->trig);
>
> -       return devm_iio_trigger_register(hw->dev, hw->trig);
> +       return err;
>  }
>
>  static int hts221_buffer_preenable(struct iio_dev *iio_dev)
> --
> 2.36.0
diff mbox series

Patch

diff --git a/drivers/iio/humidity/hts221_buffer.c b/drivers/iio/humidity/hts221_buffer.c
index f29692b9d2db..66b32413cf5e 100644
--- a/drivers/iio/humidity/hts221_buffer.c
+++ b/drivers/iio/humidity/hts221_buffer.c
@@ -135,9 +135,12 @@  int hts221_allocate_trigger(struct iio_dev *iio_dev)
 
 	iio_trigger_set_drvdata(hw->trig, iio_dev);
 	hw->trig->ops = &hts221_trigger_ops;
+
+	err = devm_iio_trigger_register(hw->dev, hw->trig);
+
 	iio_dev->trig = iio_trigger_get(hw->trig);
 
-	return devm_iio_trigger_register(hw->dev, hw->trig);
+	return err;
 }
 
 static int hts221_buffer_preenable(struct iio_dev *iio_dev)