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

["Danilo Krummrich" <dakr@kernel.org>]

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.)

[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;