Re: [PATCH v10 00/10] Fix missing fops.owner in Rust DRM/misc abstractions
From: "Danilo Krummrich" <dakr@kernel.org>
Date: 2026-08-12 21:53:47
Also in:
dri-devel, driver-core, linux-block, linux-kselftest, linux-pci, lkml, netdev, nova-gpu, rust-for-linux
Subsystem:
rust, serial device bus, the rest · Maintainers:
Miguel Ojeda, Markus Probst, Linus Torvalds
(Cc: Mark) On Wed Aug 12, 2026 at 6:33 PM CEST, Miguel Ojeda wrote:
On Tue, Aug 11, 2026 at 8:41 AM Alvin Sun [off-list ref] wrote:quoted
The series moves `THIS_MODULE` into the `ModuleMetadata` as a const, threads it through `#[vtable]` to set `fops.owner` in DRM/miscdevice, and updates configfs and rnull to use `this_module::<LocalModule>()`.Applied to `rust-next` -- thanks everyone!
This series has a semantic conflict with both the driver-core and the drm-rust tree: @Mark: When you merge driver-core-next after rust-next (which I think is the case) then you need to include the diff in [1] into the merge. In drm-rust-next the build fails with: error[E0425]: cannot find type `LocalModule` in the crate root --> rust/kernel/drm/gem/shmem.rs:628:5 | 628 | #[vtable] | ^^^^^^^^^ not found in the crate root | = note: this error originates in the attribute macro `vtable` (in Nightly builds, run with -Z macro-backtrace for more info) which is because the kunit test in rust/kernel/drm/gem/shmem.rs uses the #[vtable] macro. This should be fixed up with a patch on top of this series in rust-next. I came up with to potential solutions [2] and [3]. I think with the new build system we want [3], but I'm not entirely sure this works correctly with the current build system in all cases (at least it did survive my tests). Alternatively, we could just open-code a dummy module as in [2] for now. [1] driver-core-next merge fixup
diff --git a/rust/kernel/serdev.rs b/rust/kernel/serdev.rs
index a4927452016e..17ca504b7f8d 100644
--- a/rust/kernel/serdev.rs
+++ b/rust/kernel/serdev.rs@@ -87,7 +87,7 @@ unsafe fn register( } // SAFETY: `sdrv` is guaranteed to be a valid `DriverType`. - to_result(unsafe { bindings::__serdev_device_driver_register(sdrv.get(), module.0) }) + to_result(unsafe { bindings::__serdev_device_driver_register(sdrv.get(), module.as_ptr()) }) } unsafe fn unregister(sdrv: &Opaque<Self::DriverType>) {
[2] Open-coded dummy module
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index c04e6c5aa7e0..274924cfcc05 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs@@ -157,6 +157,15 @@ /// Prefix to appear before log messages printed from within the `kernel` crate. const __LOG_PREFIX: &[u8] = b"rust_kernel\0"; +/// Dummy module type for `#[vtable]` impl blocks within the kernel crate (e.g. kunit tests). +struct LocalModule; + +impl ModuleMetadata for LocalModule { + const NAME: &'static str::CStr = c"rust_kernel"; + // SAFETY: `try_module_get`/`module_put` handle null module pointers gracefully. + const THIS_MODULE: ThisModule = unsafe { ThisModule::from_ptr(core::ptr::null_mut()) }; +} + #[cfg(not(testlib))] #[panic_handler] fn panic(info: &core::panic::PanicInfo<'_>) -> ! {
[3] Allow module!() for kernel crate
diff --git a/rust/Makefile b/rust/Makefile
index 48adcd9b7851..4f6bf1b4d194 100644
--- a/rust/Makefile
+++ b/rust/Makefile@@ -279,6 +279,7 @@ rustdoc-pin_init: $(src)/pin-init/src/lib.rs rustdoc-pin_init_internal \ +$(call if_changed,rustdoc) rustdoc-kernel: private is-kernel-object := y +rustdoc-kernel: private rustc_target_envs = RUST_MODFILE=kernel/lib.rs rustdoc-kernel: private rustc_target_flags = --extern ffi --extern pin_init \ --extern build_error --extern macros \ --extern bindings --extern uapi \
@@ -351,6 +352,7 @@ rusttestlib-pin_init: $(src)/pin-init/src/lib.rs rusttestlib-macros \ rusttestlib-pin_init_internal $(obj)/$(libpin_init_internal_name) FORCE +$(call if_changed,rustc_test_library) +rusttestlib-kernel: private rustc_target_envs = RUST_MODFILE=kernel/lib.rs rusttestlib-kernel: private rustc_target_flags = --extern ffi \ --extern build_error --extern macros --extern pin_init \ --extern bindings --extern uapi \
@@ -386,6 +388,7 @@ quiet_cmd_rustdoc_test_kernel = RUSTDOC TK $< rm -rf $(objtree)/$(obj)/test/doctests/kernel; \ mkdir -p $(objtree)/$(obj)/test/doctests/kernel; \ $(rustc_target_envs) \ + RUST_MODFILE=kernel/lib.rs \ OBJTREE=$(abspath $(objtree)) \ $(RUSTDOC) --test $(filter-out --remap-path-scope=%,$(rust_flags)) \ -L$(objtree)/$(obj) --extern ffi --extern pin_init \
@@ -788,6 +791,7 @@ $(obj)/uapi.o: $(src)/uapi/lib.rs \ $(obj)/uapi/uapi_generated.rs FORCE +$(call if_changed_rule,rustc_library) +$(obj)/kernel.o: private rustc_target_envs = RUST_MODFILE=kernel/lib.rs $(obj)/kernel.o: private rustc_target_flags = --extern ffi --extern pin_init \ --extern build_error --extern macros --extern bindings --extern uapi \ --extern zerocopy --extern zerocopy_derive
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index c04e6c5aa7e0..7df9159788ad 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs@@ -154,8 +154,21 @@ }; pub use uapi; -/// Prefix to appear before log messages printed from within the `kernel` crate. -const __LOG_PREFIX: &[u8] = b"rust_kernel\0"; +struct KernelCrateModule; + +impl Module for KernelCrateModule { + fn init(_module: &'static ThisModule) -> error::Result<Self> { + Ok(Self) + } +} + +macros::module! { + type: KernelCrateModule, + name: "rust_kernel", + authors: ["Rust for Linux Contributors"], + description: "The kernel crate", + license: "GPL", +} #[cfg(not(testlib))] #[panic_handler]