On Mon, 30 Jan 2023 10:37:42 +0100
Mårten Lindahl <marten.lindahl@xxxxxxxx> wrote:
> There are different init functions for the sensors in this driver in
> which only one initialize the generic vcnl4000_lock. With commit
> e21b5b1f2 ("iio: light: vcnl4000: Preserve conf bits when toggle power")
> the vcnl4040 sensor started to depend on the lock, but it was missed to
> initialize it in vcnl4040's init function. This has not been visible
> until we run lockdep on it:
>
> DEBUG_LOCKS_WARN_ON(lock->magic != lock)
> WARNING: CPU: 1 PID: 8800 at kernel/locking/mutex.c:575 __mutex_lock+0x4f8/0x890
> ...
> Call trace:
> __mutex_lock
> mutex_lock_nested
> vcnl4200_set_power_state
> vcnl4200_init
> vcnl4000_probe
> i2c_device_probe
> really_probe
> __driver_probe_device
> driver_probe_device
> __driver_attach
> bus_for_each_dev
> driver_attach
> bus_add_driver
> driver_register
> i2c_register_driver
> vcnl4000_driver_init
> do_one_initcall
> do_init_module
> load_module
> __do_sys_finit_module
> ...
>
> Fix this by adding mutex_init on the lock in the init function used for
> vcnl4040.
>
> Fixes: e21b5b1f2 ("iio: light: vcnl4000: Preserve conf bits when toggle power")
> Signed-off-by: Mårten Lindahl <marten.lindahl@xxxxxxxx>
Perhaps better to pull the lock out of the device specific setup?
> ---
> drivers/iio/light/vcnl4000.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/iio/light/vcnl4000.c b/drivers/iio/light/vcnl4000.c
> index cc1a2062e76d..a8a9fc3b1a02 100644
> --- a/drivers/iio/light/vcnl4000.c
> +++ b/drivers/iio/light/vcnl4000.c
> @@ -316,6 +316,7 @@ static int vcnl4200_init(struct vcnl4000_data *data)
> }
> mutex_init(&data->vcnl4200_al.lock);
> mutex_init(&data->vcnl4200_ps.lock);
> + mutex_init(&data->vcnl4000_lock);
>
> ret = data->chip_spec->set_power_state(data, true);
> if (ret < 0)
