6.12-stable review patch. If anyone has any objections, please let me know.
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From: Miguel Ojeda ojeda@kernel.org
commit 7129ea6e242b00938532537da41ddf5fa3e21471 upstream.
Starting with Rust 1.88.0 (expected 2025-06-26) [1][2], `rustc` may introduce a new lint that catches unnecessary transmutes, e.g.:
error: unnecessary transmute --> rust/uapi/uapi_generated.rs:23242:18 | 23242 | unsafe { ::core::mem::transmute(self._bitfield_1.get(0usize, 1u8) as u8) } | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace this with: `(self._bitfield_1.get(0usize, 1u8) as u8 == 1)` | = note: `-D unnecessary-transmutes` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(unnecessary_transmutes)]`
There are a lot of them (at least 300), but luckily they are all in `bindgen`-generated code.
Thus clean all up by allowing it there.
Since unknown lints trigger a lint itself in older compilers, do it conditionally so that we can keep the `unknown_lints` lint enabled.
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Link: https://github.com/rust-lang/rust/pull/136083 [1] Link: https://github.com/rust-lang/rust/issues/136067 [2] Reviewed-by: Alice Ryhl aliceryhl@google.com Link: https://lore.kernel.org/r/20250502140237.1659624-4-ojeda@kernel.org Signed-off-by: Miguel Ojeda ojeda@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- init/Kconfig | 3 +++ rust/bindings/lib.rs | 1 + rust/uapi/lib.rs | 1 + 3 files changed, 5 insertions(+)
--- a/init/Kconfig +++ b/init/Kconfig @@ -134,6 +134,9 @@ config LD_CAN_USE_KEEP_IN_OVERLAY # https://github.com/llvm/llvm-project/pull/130661 def_bool LD_IS_BFD || LLD_VERSION >= 210000
+config RUSTC_HAS_UNNECESSARY_TRANSMUTES + def_bool RUSTC_VERSION >= 108800 + config PAHOLE_VERSION int default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE)) --- a/rust/bindings/lib.rs +++ b/rust/bindings/lib.rs @@ -26,6 +26,7 @@
#[allow(dead_code)] #[allow(clippy::undocumented_unsafe_blocks)] +#[cfg_attr(CONFIG_RUSTC_HAS_UNNECESSARY_TRANSMUTES, allow(unnecessary_transmutes))] mod bindings_raw { // Manual definition for blocklisted types. type __kernel_size_t = usize; --- a/rust/uapi/lib.rs +++ b/rust/uapi/lib.rs @@ -24,6 +24,7 @@ unreachable_pub, unsafe_op_in_unsafe_fn )] +#![cfg_attr(CONFIG_RUSTC_HAS_UNNECESSARY_TRANSMUTES, allow(unnecessary_transmutes))]
// Manual definition of blocklisted types. type __kernel_size_t = usize;