Re: [PATCH v2 0/4] driver core: generalize driver_override infrastructure

On Tue, Mar 3, 2026 at 7:57 PM Danilo Krummrich <[email protected]> wrote:
>
> Currently, there are 12 busses (including platform and PCI) that duplicate the
> driver_override logic for their individual devices.
>
> All of them seem to be prone to the bug described in [1].
>
> While this could be solved for every bus individually using a separate lock,
> solving this in the driver-core generically results in less (and cleaner)
> changes overall.
>
> Thus, move driver_override to struct device, provide corresponding accessors for
> busses and handle locking with a separate lock internally.
>
> In particular, add device_set_driver_override(), device_has_driver_override(),
> device_match_driver_override() and a helper, DEVICE_ATTR_DRIVER_OVERRIDE(), to
> declare the corresponding sysfs store() and show() callbacks.

Hi Danilo,

Thanks for the v2. The code looks good and the bus_type approach is
much cleaner.

Just a minor note on the commit messages for the cover letter and
patch 1: they still mention adding the DEVICE_ATTR_DRIVER_OVERRIDE()
helper, even though it was correctly dropped in this version.

Thanks.

>
> Until all busses have migrated, keep driver_set_override() in place.
>
> Note that we can't use the device lock for the reasons described in [2].
>
> This patch series includes the migration of the platform bus; patches for all
> other affected busses still need to be extracted as a follow-up of the WIP
> treewide patch in [3].
>
> [1] https://bugzilla.kernel.org/show_bug.cgi?id=220789
> [2] https://lore.kernel.org/driver-core/[email protected]/
> [3] https://git.kernel.org/pub/scm/linux/kernel/git/dakr/linux.git/log/?h=driver_override
>
> Changes in v2:
>   - Drop DEVICE_ATTR_DRIVER_OVERRIDE() and make driver_override a
>     struct bus_type feature instead.
>   - Add driver_override documentation in .../driver-model/binding.rst.
>   - Move kfree(dev->driver_override.name) before release().
>   - hwmon: axi-fan: Use NULL instead of dev_name() in
>     devm_request_threaded_irq().
>
> Danilo Krummrich (4):
>   driver core: generalize driver_override in struct device
>   docs: driver-model: document driver_override
>   hwmon: axi-fan: don't use driver_override as IRQ name
>   driver core: platform: use generic driver_override infrastructure
>
>  .../driver-api/driver-model/binding.rst       | 48 +++++++++++++++
>  arch/sh/drivers/platform_early.c              |  6 +-
>  drivers/base/bus.c                            | 43 ++++++++++++-
>  drivers/base/core.c                           |  2 +
>  drivers/base/dd.c                             | 60 +++++++++++++++++++
>  drivers/base/platform.c                       | 37 ++----------
>  drivers/bus/simple-pm-bus.c                   |  4 +-
>  drivers/clk/imx/clk-scu.c                     |  3 +-
>  drivers/hwmon/axi-fan-control.c               |  2 +-
>  drivers/slimbus/qcom-ngd-ctrl.c               |  6 +-
>  include/linux/device.h                        | 54 +++++++++++++++++
>  include/linux/device/bus.h                    |  4 ++
>  include/linux/platform_device.h               |  5 --
>  sound/soc/samsung/i2s.c                       |  6 +-
>  14 files changed, 228 insertions(+), 52 deletions(-)
>
>
> base-commit: 11439c4635edd669ae435eec308f4ab8a0804808
> --
> 2.53.0
>