On Tue, 31 Jan 2023 16:14:11 +0200
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> wrote:
> On Tue, Jan 31, 2023 at 03:01:09PM +0100, Mårten Lindahl wrote:
> > There are different init functions for the sensors in this driver in
> > which only one initializes the generic vcnl4000_lock. With commit
> > e21b5b1f2669 ("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)
> > 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
> >
> > Fix this by initializing the lock in the probe function instead of doing
> > it in the chip specific init functions.
>
> Fine now, thanks!
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
>
> > Fixes: e21b5b1f2669 ("iio: light: vcnl4000: Preserve conf bits when toggle power")
> > Signed-off-by: Mårten Lindahl <marten.lindahl@xxxxxxxx>
Applied to the fixes-togreg branch and marked for stable.
Thanks,
Jonathan
> > ---
> >
> > v3:
> > - Trimmed backtrace in commit message even more
> > - New line before mutex_init
> >
> > v2:
> > - Trimmed backtrace in commit message
> > - Have 12 digit sha-1 id in Fixes tag
> > - Make the lock initialization in probe instead of in _init function
> >
> > drivers/iio/light/vcnl4000.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/iio/light/vcnl4000.c b/drivers/iio/light/vcnl4000.c
> > index cc1a2062e76d..69c5bc987e26 100644
> > --- a/drivers/iio/light/vcnl4000.c
> > +++ b/drivers/iio/light/vcnl4000.c
> > @@ -199,7 +199,6 @@ static int vcnl4000_init(struct vcnl4000_data *data)
> >
> > data->rev = ret & 0xf;
> > data->al_scale = 250000;
> > - mutex_init(&data->vcnl4000_lock);
> >
> > return data->chip_spec->set_power_state(data, true);
> > };
> > @@ -1197,6 +1196,8 @@ static int vcnl4000_probe(struct i2c_client *client)
> > data->id = id->driver_data;
> > data->chip_spec = &vcnl4000_chip_spec_cfg[data->id];
> >
> > + mutex_init(&data->vcnl4000_lock);
> > +
> > ret = data->chip_spec->init(data);
> > if (ret < 0)
> > return ret;
> > --
> > 2.30.2
> >
>
