Re: [PATCH] iio: gyro: mpu3050: add missing trigger cleanup on remove

[Joshua Crofts]

On Sun, 11 Oct 2026 17:53:01 +0200
Joshua Crofts <joshua.crofts1@xxxxxxxxx> wrote:
>  drivers/iio/gyro/mpu3050-core.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 

Sashiko review came back and the issue doesn't seem so
straight-forward. I'll probably introduce a local pointer
and then assign it to the mpu3050 data struct.

Attaching Sashiko review below.

> diff --git a/drivers/iio/gyro/mpu3050-core.c b/drivers/iio/gyro/mpu3050-core.c
> index 07c0f9011c63..096fd0dc608e 100644
> --- a/drivers/iio/gyro/mpu3050-core.c
> +++ b/drivers/iio/gyro/mpu3050-core.c
> @@ -1260,6 +1260,8 @@ int mpu3050_common_probe(struct device *dev,
>  	pm_runtime_get_sync(dev);
>  	pm_runtime_put_noidle(dev);
>  	pm_runtime_disable(dev);
> +	if (mpu3050->trig)
> +		iio_trigger_unregister(mpu3050->trig);


Does this unconditionally unregister a trigger that may not have been
successfully registered?

If mpu3050_trigger_probe() fails (for example, if request_threaded_irq()
fails), mpu3050->trig is allocated via devm_iio_trigger_alloc() but it will
never have successfully completed iio_trigger_register().

mpu3050_common_probe() catches that error, logs "failed to register trigger",
and continues. If a subsequent step like iio_device_register() fails, this
code will call iio_trigger_unregister() on the uninitialized trigger.

Because the trigger was never registered via iio_trigger_register(),
iio_trigger_unregister() will call device_del() on a device that was never
added, and ida_free() on an unallocated ID, which can lead to a crash.

>  	if (irq)
>  		free_irq(mpu3050->irq, mpu3050->trig);
>  	iio_triggered_buffer_cleanup(indio_dev);
> @@ -1278,6 +1280,8 @@ void mpu3050_common_remove(struct device *dev)
>  	pm_runtime_get_sync(dev);
>  	pm_runtime_put_noidle(dev);
>  	pm_runtime_disable(dev);
> +	if (mpu3050->trig)
> +		iio_trigger_unregister(mpu3050->trig);

Can this cause a kernel crash during normal driver teardown if the trigger
probe originally failed?

Similar to the probe error path above, if mpu3050_trigger_probe() failed
during initialization, mpu3050->trig is left allocated but unregistered.

Calling iio_trigger_unregister() here on that uninitialized trigger will
cause the same teardown issues during driver removal.

-- 
Kind regards,
Joshua Crofts