[PATCH] iio: light: vcnl4000: Fix WARN_ON on uninitialized lock

[PATCH] iio: light: vcnl4000: Fix WARN_ON on uninitialized lock

[Mårten Lindahl]

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@axis.com>
---
 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)
-- 
2.30.2

Re: [PATCH] iio: light: vcnl4000: Fix WARN_ON on uninitialized lock

[Andy Shevchenko]

On Mon, Jan 30, 2023 at 10:37:42AM +0100, Mårten Lindahl 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
>    ...

https://www.kernel.org/doc/html/latest/process/submitting-patches.html#backtraces-in-commit-messages

Otherwise looks good to me,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> 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@axis.com>
> ---
>  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)
> -- 
> 2.30.2
> 

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] iio: light: vcnl4000: Fix WARN_ON on uninitialized lock

[Andy Shevchenko]

On Mon, Jan 30, 2023 at 02:39:12PM +0200, Andy Shevchenko wrote:
> On Mon, Jan 30, 2023 at 10:37:42AM +0100, Mårten Lindahl wrote:

...

> > Fixes: e21b5b1f2 ("iio: light: vcnl4000: Preserve conf bits when toggle power")

Actually one more, please provide a proper Fixes tag.

https://www.kernel.org/doc/html/latest/process/submitting-patches.html#describe-your-changes

It's explained there.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] iio: light: vcnl4000: Fix WARN_ON on uninitialized lock

[Jonathan Cameron]

On Mon, 30 Jan 2023 10:37:42 +0100
Mårten Lindahl <marten.lindahl@axis.com> 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@axis.com>

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)

Re: [PATCH] iio: light: vcnl4000: Fix WARN_ON on uninitialized lock

[Mårten Lindahl]

On 1/30/23 13:40, Andy Shevchenko wrote:
> On Mon, Jan 30, 2023 at 02:39:12PM +0200, Andy Shevchenko wrote:
>> On Mon, Jan 30, 2023 at 10:37:42AM +0100, Mårten Lindahl wrote:
> ...
>
>>> Fixes: e21b5b1f2 ("iio: light: vcnl4000: Preserve conf bits when toggle power")
> Actually one more, please provide a proper Fixes tag.
>
> https://www.kernel.org/doc/html/latest/process/submitting-patches.html#describe-your-changes
>
> It's explained there.
>
Hi Andy! Sorry, I'll fix those.

Kind regards

Mårten

Re: [PATCH] iio: light: vcnl4000: Fix WARN_ON on uninitialized lock

[Mårten Lindahl]

On 1/30/23 14:04, Jonathan Cameron wrote:
> On Mon, 30 Jan 2023 10:37:42 +0100
> Mårten Lindahl <marten.lindahl@axis.com> 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@axis.com>
> Perhaps better to pull the lock out of the device specific setup?

Hi Jonathan!

Ok, having a

static DEFINE_MUTEX(vcnl4000_lock);

will make sure initializing it wont be forgotten for specific setups.

I'll test it.

Kind regards

Mårten

>
>> ---
>>   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)

Re: [PATCH] iio: light: vcnl4000: Fix WARN_ON on uninitialized lock

[Jonathan Cameron]

On Mon, 30 Jan 2023 15:10:40 +0100
Mårten Lindahl <martenli@axis.com> wrote:

> On 1/30/23 14:04, Jonathan Cameron wrote:
> > On Mon, 30 Jan 2023 10:37:42 +0100
> > Mårten Lindahl <marten.lindahl@axis.com> 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@axis.com>  
> > Perhaps better to pull the lock out of the device specific setup?  
> 
> Hi Jonathan!
> 
> Ok, having a
> 
> static DEFINE_MUTEX(vcnl4000_lock);
> 
No. Definitely don't do that.  We need one per device instance.

I just meant move the mutex_init() into the main probe function rather
than the chip specific init that is called from there.

> will make sure initializing it wont be forgotten for specific setups.
> 
> I'll test it.
> 
> Kind regards
> 
> Mårten
> 
> >  
> >> ---
> >>   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)  

Re: [PATCH] iio: light: vcnl4000: Fix WARN_ON on uninitialized lock

[Mårten Lindahl]

On 1/30/23 18:30, Jonathan Cameron wrote:
> On Mon, 30 Jan 2023 15:10:40 +0100
> Mårten Lindahl <martenli@axis.com> wrote:
>
>> On 1/30/23 14:04, Jonathan Cameron wrote:
>>> On Mon, 30 Jan 2023 10:37:42 +0100
>>> Mårten Lindahl <marten.lindahl@axis.com> 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@axis.com>
>>> Perhaps better to pull the lock out of the device specific setup?
>> Hi Jonathan!
>>
>> Ok, having a
>>
>> static DEFINE_MUTEX(vcnl4000_lock);
>>
> No. Definitely don't do that.  We need one per device instance.
>
> I just meant move the mutex_init() into the main probe function rather
> than the chip specific init that is called from there.

Ok, sorry for the missunderstanding. I''ll fix it.

Kind regards

Mårten

>
>> will make sure initializing it wont be forgotten for specific setups.
>>
>> I'll test it.
>>
>> Kind regards
>>
>> Mårten
>>
>>>   
>>>> ---
>>>>    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)