linux/rust
Lyude Paul 5ae65bdcb8 Partially revert "rust: drm: gem: Implement AlwaysRefCounted for all gem objects automatically"
Currently in order to implement AlwaysRefCounted for gem objects, we use a
blanket implementation:

  unsafe impl<T: IntoGEMObject> AlwaysRefCounted for T { … }

While this technically works, it comes with the rather unfortunate downside
that attempting to create a similar blanket implementation in any other
kernel crate will now fail in a rather confusing way.

Using an example from the (not yet upstream) rust DRM KMS bindings, if we
were to add:

  unsafe impl<T: RcModeObject> AlwaysRefCounted for T { … }

Then the moment that both blanket implementations are present in the same
kernel tree, compilation fails with the following:

   error[E0119]: conflicting implementations of trait `types::AlwaysRefCounted`
      --> rust/kernel/drm/kms.rs:504:1
       |
   504 | unsafe impl<T: RcModeObject> AlwaysRefCounted for T {
       | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation
       |
      ::: rust/kernel/drm/gem/mod.rs:97:1
       |
   97  | unsafe impl<T: IntoGEMObject> AlwaysRefCounted for T {
       | ---------------------------------------------------- first implementation here

So, revert these changes for now. The proper fix for this is to introduce a
macro for copy/pasting the same implementation of AlwaysRefCounted around.

This reverts commit 38cb08c3fc.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20251016210955.2813186-2-lyude@redhat.com
History 2025-10-21 14:15:20 -04:00
..
bindings mm/ksm: fix flag-dropping behavior in ksm_madvise 2025-10-07 14:01:12 -07:00
helpers Char/Misc/IIO/Binder changes for 6.18-rc1 2025-10-04 16:26:32 -07:00
kernel Partially revert "rust: drm: gem: Implement AlwaysRefCounted for all gem objects automatically" 2025-10-21 14:15:20 -04:00
macros linux_kselftest-kunit-6.18-rc1 2025-10-01 19:15:11 -07:00
pin-init rust: pin-init: add references to previously initialized fields 2025-09-11 23:30:02 +02:00
uapi Char/Misc/IIO/Binder changes for 6.18-rc1 2025-10-04 16:26:32 -07:00
.gitignore rust: support running Rust documentation tests as KUnit ones 2023-07-19 09:32:53 -06:00
.kunitconfig rust: add kunitconfig 2025-03-19 23:22:21 +01:00
bindgen_parameters rust: derive Zeroable for all structs & unions generated by bindgen where possible 2025-09-08 14:03:17 +02:00
build_error.rs rust: add build_error crate 2022-12-04 01:59:16 +01:00
compiler_builtins.rs ARM: 9441/1: rust: Enable Rust support for ARMv7 2025-03-26 13:31:16 +00:00
exports.c rust: exports: improve grammar in commentary 2024-10-21 17:35:33 +02:00
ffi.rs rust: use absolute paths in macros referencing core and kernel 2025-05-23 00:12:14 +02:00
Makefile rust: add pin-init as a dependency to bindings and uapi 2025-09-08 13:42:39 +02:00