[PATCH v1 0/5] iio: treewide: rearrange iio trig get/register

[PATCH v1 0/5] iio: treewide: rearrange iio trig get/register

[Dmitry Rokosov]

The following patchset resolves problems with iio_trigger_get() and
iio_trigger_register() call order in the different IIO drivers.

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.

Dmitry Rokosov (5):
  iio:accel:bma180: rearrange iio trigger get and register
  iio:accel:kxcjk-1013: rearrange iio trigger get and register
  iio:accel:mxc4005: rearrange iio trigger get and register
  iio:chemical:ccs811: rearrange iio trigger get and register
  iio:humidity:hts221: rearrange iio trigger get and register

 drivers/iio/accel/bma180.c           | 3 ++-
 drivers/iio/accel/kxcjk-1013.c       | 4 ++--
 drivers/iio/accel/mxc4005.c          | 4 ++--
 drivers/iio/chemical/ccs811.c        | 4 ++--
 drivers/iio/humidity/hts221_buffer.c | 5 ++++-
 5 files changed, 12 insertions(+), 8 deletions(-)

-- 
2.36.0

[PATCH v1 1/5] iio:accel:bma180: rearrange iio trigger get and register

[Dmitry Rokosov]

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@sberdevices.ru>
---
 drivers/iio/accel/bma180.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/accel/bma180.c b/drivers/iio/accel/bma180.c
index d8a454c266d5..5d0bd0fc3018 100644
--- a/drivers/iio/accel/bma180.c
+++ b/drivers/iio/accel/bma180.c
@@ -1006,11 +1006,12 @@ static int bma180_probe(struct i2c_client *client,
 
 		data->trig->ops = &bma180_trigger_ops;
 		iio_trigger_set_drvdata(data->trig, indio_dev);
-		indio_dev->trig = iio_trigger_get(data->trig);
 
 		ret = iio_trigger_register(data->trig);
 		if (ret)
 			goto err_trigger_free;
+
+		indio_dev->trig = iio_trigger_get(data->trig);
 	}
 
 	ret = iio_triggered_buffer_setup(indio_dev, NULL,
-- 
2.36.0

[PATCH v1 2/5] iio:accel:kxcjk-1013: rearrange iio trigger get and register

[Dmitry Rokosov]

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@sberdevices.ru>
---
 drivers/iio/accel/kxcjk-1013.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/accel/kxcjk-1013.c b/drivers/iio/accel/kxcjk-1013.c
index ac74cdcd2bc8..748b35c2f0c3 100644
--- a/drivers/iio/accel/kxcjk-1013.c
+++ b/drivers/iio/accel/kxcjk-1013.c
@@ -1554,12 +1554,12 @@ static int kxcjk1013_probe(struct i2c_client *client,
 
 		data->dready_trig->ops = &kxcjk1013_trigger_ops;
 		iio_trigger_set_drvdata(data->dready_trig, indio_dev);
-		indio_dev->trig = data->dready_trig;
-		iio_trigger_get(indio_dev->trig);
 		ret = iio_trigger_register(data->dready_trig);
 		if (ret)
 			goto err_poweroff;
 
+		indio_dev->trig = iio_trigger_get(data->dready_trig);
+
 		data->motion_trig->ops = &kxcjk1013_trigger_ops;
 		iio_trigger_set_drvdata(data->motion_trig, indio_dev);
 		ret = iio_trigger_register(data->motion_trig);
-- 
2.36.0

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

[Dmitry Rokosov]

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@sberdevices.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

[PATCH v1 4/5] iio:chemical:ccs811: rearrange iio trigger get and register

[Dmitry Rokosov]

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@sberdevices.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

Re: [PATCH v1 0/5] iio: treewide: rearrange iio trig get/register

[Andy Shevchenko]

On Mon, May 23, 2022 at 6:42 PM Dmitry Rokosov <DDRokosov@sberdevices.ru> wrote:
>
> The following patchset resolves problems with iio_trigger_get() and
> iio_trigger_register() call order in the different IIO drivers.
>
> 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

dereference

> completely incorrect.

Cool set! But it sounds like a set of fixes, can you add a Fixes tag
to each of the patches?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v1 0/5] iio: treewide: rearrange iio trig get/register

[Dmitry Rokosov]

On Mon, May 23, 2022 at 07:40:27PM +0200, Andy Shevchenko wrote:
Hello Andy,

Thank you for quick feedback.

On Mon, May 23, 2022 at 07:40:27PM +0200, Andy Shevchenko wrote:
> > If this call order is wrong, the next iio_trigger_put() (from sysfs
> > callbacks or rmmod) will derefence "default" module refcnt, which is
> 
> dereference
Ah... good catch.

> > completely incorrect.
> 
> Cool set! But it sounds like a set of fixes, can you add a Fixes tag
> to each of the patches?
Sure, no problem, will provide Fixes tags in the next version.

-- 
Thank you,
Dmitry

[PATCH v1 5/5] iio:humidity:hts221: rearrange iio trigger get and register

[Dmitry Rokosov]

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@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