Re: [PATCH 00/12] treewide: Convert buses to use generic driver_override

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Mar 24, 2026 at 01:59:04AM +0100, Danilo Krummrich wrote:
> This is the follow-up of the driver_override generalization in [1], converting
> the remaining 11 busses and removing the now-unused driver_set_override()
> helper.
> 
> All of them (except AP, which has a different race condition) are prone to the
> potential UAF described in [2], caused by accessing the driver_override field
> from their corresponding match() callback.
> 
> In order to address this, the generalized driver_override field in struct device
> is protected with a spinlock. The driver-core provides accessors, such as
> device_match_driver_override(), device_has_driver_override() and
> device_set_driver_override(), which all ensure proper locking internally.
> 
> Additionally, the driver-core provides a driver_override flag in struct
> bus_type, which, once enabled, automatically registers generic sysfs callbacks,
> allowing userspace to modify the driver_override field.
> 
> SPI and AP are a bit special; both print "\n" when driver_override is not set,
> whereas all other buses (and thus the driver-core) produce "(null)\n" in this
> case.
> 
> Hence, SPI and AP do not take advantage of the driver_override flag in struct
> bus_type; AP additionally maintains a counter in its custom sysfs store().
> 
> Technically, we could support a custom fallback string when driver_override is
> unset in struct bus_type, but only SPI would benefit from this, since AP has
> additional custom logic in store() anyways.
> 
> (I'm not sure if there are userspace programs that strictly rely on this;
> driverctl seems to check for both, but I rather not break some userspace tool
> I'm not aware of. :)
> 
> This series is based on v7.0-rc5 with no additional dependencies, hence those
> patches can be picked up by subsystems individually.
> 
> [1] https://lore.kernel.org/driver-core/20260303115720.48783-1-dakr@kernel.org/
> [2] https://bugzilla.kernel.org/show_bug.cgi?id=220789
> [3] https://gitlab.com/driverctl/driverctl/-/blob/0.121/driverctl?ref_type=tags#L99

vdpa bits:

Acked-by: Michael S. Tsirkin <mst@redhat.com>

I assume it'll all be merged together?

> Danilo Krummrich (12):
>   amba: use generic driver_override infrastructure
>   bus: fsl-mc: use generic driver_override infrastructure
>   cdx: use generic driver_override infrastructure
>   hv: vmbus: use generic driver_override infrastructure
>   PCI: use generic driver_override infrastructure
>   platform/wmi: use generic driver_override infrastructure
>   rpmsg: use generic driver_override infrastructure
>   vdpa: use generic driver_override infrastructure
>   s390/cio: use generic driver_override infrastructure
>   s390/ap: use generic driver_override infrastructure
>   spi: use generic driver_override infrastructure
>   driver core: remove driver_set_override()
> 
>  drivers/amba/bus.c                 | 37 +++------------
>  drivers/base/driver.c              | 75 ------------------------------
>  drivers/bus/fsl-mc/fsl-mc-bus.c    | 43 +++--------------
>  drivers/cdx/cdx.c                  | 40 ++--------------
>  drivers/hv/vmbus_drv.c             | 36 ++------------
>  drivers/pci/pci-driver.c           | 11 +++--
>  drivers/pci/pci-sysfs.c            | 28 -----------
>  drivers/pci/probe.c                |  1 -
>  drivers/platform/wmi/core.c        | 36 ++------------
>  drivers/rpmsg/qcom_glink_native.c  |  2 -
>  drivers/rpmsg/rpmsg_core.c         | 43 +++--------------
>  drivers/rpmsg/virtio_rpmsg_bus.c   |  1 -
>  drivers/s390/cio/cio.h             |  5 --
>  drivers/s390/cio/css.c             | 34 ++------------
>  drivers/s390/crypto/ap_bus.c       | 34 +++++++-------
>  drivers/s390/crypto/ap_bus.h       |  1 -
>  drivers/s390/crypto/ap_queue.c     | 24 +++-------
>  drivers/spi/spi.c                  | 19 +++-----
>  drivers/vdpa/vdpa.c                | 48 ++-----------------
>  drivers/vfio/fsl-mc/vfio_fsl_mc.c  |  4 +-
>  drivers/vfio/pci/vfio_pci_core.c   |  5 +-
>  drivers/xen/xen-pciback/pci_stub.c |  6 ++-
>  include/linux/amba/bus.h           |  5 --
>  include/linux/cdx/cdx_bus.h        |  4 --
>  include/linux/device/driver.h      |  2 -
>  include/linux/fsl/mc.h             |  4 --
>  include/linux/hyperv.h             |  5 --
>  include/linux/pci.h                |  6 ---
>  include/linux/rpmsg.h              |  4 --
>  include/linux/spi/spi.h            |  5 --
>  include/linux/vdpa.h               |  4 --
>  include/linux/wmi.h                |  4 --
>  32 files changed, 88 insertions(+), 488 deletions(-)
> 
> 
> base-commit: c369299895a591d96745d6492d4888259b004a9e
> -- 
> 2.53.0