Re: [PATCH v5] driver core: enforce device_lock for driver_match_device()

[Jon Hunter <jonathanh@nvidia.com>]

Hi Danilo,

On 21/01/2026 21:42, Danilo Krummrich wrote:
> On Wed Jan 21, 2026 at 9:00 PM CET, Jon Hunter wrote:
>> It is odd because it only appears to impact the Tegra194 Jetson Xavier
>> NX board (tegra194-p3509-0000+p3668-0000.dts).
>>
>> It appears to boot enough so the test can SSH into the device, but the
>> kernel log does not show the us getting to the console prompt. It also
>> appears that a lot of drivers are not bound as expected. I would need to
>> check if those are all modules or not.
> 
> The other reports were fixed by [1], but the issue in arm-smmu-qcom shouldn't be
> related in this case.
> 
> I quickyl checked all drivers with "tegra194" in their compatible string, but
> didn't see anything odd.
> 
> Can you please try to enable CONFIG_LOCKDEP, CONFIG_PROVE_LOCKING,
> CONFIG_DEBUG_MUTEXES and see if you get a lockdep splat using the following
> diff?
> 
> (You will see a lockdep warning in faux_bus_init(), it's harmless and can be
> ignored.)

Thanks. I do the lockdep warning in faux_bus_init() but that's the only 
one. I have verified that all these CONFIGs are correctly enabled in the 
build. The device boots fine with the below diff, but I am guessing that 
that is expected?

Any other thoughts?

Thanks
Jon
  > [1] 
https://lore.kernel.org/driver-core/20260121141215.29658-1-dakr@kernel.org/
> 
> diff --git a/drivers/base/base.h b/drivers/base/base.h
> index 677320881af1..4741412d7e46 100644
> --- a/drivers/base/base.h
> +++ b/drivers/base/base.h
> @@ -190,8 +190,13 @@ static inline int driver_match_device(const struct device_driver *drv,
>   static inline int driver_match_device_locked(const struct device_driver *drv,
>                                               struct device *dev)
>   {
> -       guard(device)(dev);
> -       return driver_match_device(drv, dev);
> +       int ret;
> +
> +       mutex_acquire(&dev->mutex.dep_map, 0, 0, _THIS_IP_);
> +       ret = driver_match_device(drv, dev);
> +       mutex_release(&dev->mutex.dep_map, _THIS_IP_);
> +
> +       return ret;
>   }
> 
>   static inline void dev_sync_state(struct device *dev)
> diff --git a/drivers/base/core.c b/drivers/base/core.c
> index 40de2f51a1b1..56c62b3016aa 100644
> --- a/drivers/base/core.c
> +++ b/drivers/base/core.c
> @@ -2557,6 +2557,8 @@ static void device_release(struct kobject *kobj)
> 
>          kfree(dev->dma_range_map);
> 
> +       lockdep_unregister_key(&dev->lock_key);
> +
>          if (dev->release)
>                  dev->release(dev);
>          else if (dev->type && dev->type->release)
> @@ -3159,7 +3161,9 @@ void device_initialize(struct device *dev)
>          kobject_init(&dev->kobj, &device_ktype);
>          INIT_LIST_HEAD(&dev->dma_pools);
>          mutex_init(&dev->mutex);
> -       lockdep_set_novalidate_class(&dev->mutex);
> +       //lockdep_set_novalidate_class(&dev->mutex);
> +       lockdep_register_key(&dev->lock_key);
> +       lockdep_set_class(&dev->mutex, &dev->lock_key);
>          spin_lock_init(&dev->devres_lock);
>          INIT_LIST_HEAD(&dev->devres_head);
>          device_pm_init(dev);
> diff --git a/include/linux/device.h b/include/linux/device.h
> index 0be95294b6e6..dc898a420bc2 100644
> --- a/include/linux/device.h
> +++ b/include/linux/device.h
> @@ -579,6 +579,7 @@ struct device {
>          struct mutex            mutex;  /* mutex to synchronize calls to
>                                           * its driver.
>                                           */
> +       struct lock_class_key lock_key;
> 
>          struct dev_links_info   links;
>          struct dev_pm_info      power;
> 

-- 
nvpublic