Re: [PATCH 0/2] rust: usb: add initial USB abstractions

[Alice Ryhl <aliceryhl@google.com>]

On Tue, Sep 23, 2025 at 2:05 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Mon, Aug 25, 2025 at 03:18:04PM -0300, Daniel Almeida wrote:
> > This adds initial support for USB Rust drivers, not only because I see a
> > widespread use of module_usb_driver() in media (which is a subsystem I
> > aim to support) but also because I want to learn about USB in general
> > and this is a nice opportunity to start doing so.
> >
> > I tried to keep things as consistent with pci.rs and platform.rs as
> > possible and tested it by manually binding a device (i.e.: my Logitech
> > mouse) to the sample driver via:
> >
> > /sys/bus/usb/drivers/rust_driver_usb/new_id
> >
> > This initial patch is therefore comprised of the same patterns that are
> > known to work for pci and platform already.
> >
> > Physically disconnecting the device also worked, i.e.: nothing bad
> > showed up in dmesg.
> >
> > Note that I did not touch MAINTAINERS at all. The objective is to
> > kickstart the discussion of what to do there here in v1.
>
> I tried to apply these, but I get the following build error when adding
> to the char-misc-testing tree:
>
> ld.lld: error: undefined symbol: usb_get_intf
> >>> referenced by kernel.1a949e63ee2acc6a-cgu.0
> >>>               rust/kernel.o:(<kernel::usb::Interface as kernel::sync::aref::AlwaysRefCounted>::inc_ref) in archive vmlinux.a
> >>> referenced by kernel.1a949e63ee2acc6a-cgu.0
> >>>               rust/kernel.o:(<kernel::sync::aref::ARef<kernel::usb::Interface> as core::convert::From<&kernel::usb::Interface<kernel::device::CoreInternal>>>::from) in archive vmlinux.a
>
> ld.lld: error: undefined symbol: usb_put_intf
> >>> referenced by kernel.1a949e63ee2acc6a-cgu.0
> >>>               rust/kernel.o:(<kernel::usb::Interface as kernel::sync::aref::AlwaysRefCounted>::dec_ref) in archive vmlinux.a
>
> ld.lld: error: undefined symbol: usb_get_dev
> >>> referenced by kernel.1a949e63ee2acc6a-cgu.0
> >>>               rust/kernel.o:(<kernel::usb::Device as kernel::sync::aref::AlwaysRefCounted>::inc_ref) in archive vmlinux.a
> >>> referenced by kernel.1a949e63ee2acc6a-cgu.0
> >>>               rust/kernel.o:(<kernel::sync::aref::ARef<kernel::usb::Device> as core::convert::From<&kernel::usb::Device<kernel::device::CoreInternal>>>::from) in archive vmlinux.a
>
> ld.lld: error: undefined symbol: usb_put_dev
> >>> referenced by kernel.1a949e63ee2acc6a-cgu.0
> >>>               rust/kernel.o:(<kernel::usb::Device as kernel::sync::aref::AlwaysRefCounted>::dec_ref) in archive vmlinux.a
>
>
> Any hints?

Did you enable CONFIG_USB?

Alice