From nobody Wed Apr 1 22:11:53 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1F366324B16; Wed, 1 Apr 2026 11:47:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775044023; cv=none; b=PKfjfAZT7V1qjQ5LRVHztJME0uajZXBqFW4LsRLvm5A28Ap+WvR/UubCUkIKalYarn1/PK6Ctwv6bMsmdnbDeJVstpJHMBNEpiKR4ZOHXUc/t6BuJSTtx3PBmACLV6l3v03OoC08kC0o01nGDQ8BGVGi8WOEMSs/65ZYY+76mFM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775044023; c=relaxed/simple; bh=Mw52drxgGUxVV9g2ax+bN00+Y+DwaOQAPKLe9BmgAy4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=F8Cc8z0CZ4zM37MExkDCppZ05hU0EOfG4zPxFtH/6cRaIUCE7symOyEosLqkiLVxhEvPuHH9wY1WYPMm1bTdGvTYdONUt7MtZTgJBtJFv/KMxlBYfE9gruDj3zztZcSwgEsLW7IDLNbeRZgu3hv3XU7dcaKUJzIWK0CL51tkX7c= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ugWT6S5R; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ugWT6S5R" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 74DC6C4CEF7; Wed, 1 Apr 2026 11:46:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775044022; bh=Mw52drxgGUxVV9g2ax+bN00+Y+DwaOQAPKLe9BmgAy4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ugWT6S5Rks7JPny9Cbv3J54JQDqN0ZafIZl0tQRG/BsxkABfq5N56hz+HGTTf4QwF WiRyg2jtIsN33RPoZYMpId+EKAU/CCVoqlxQN7bAyCsVHubJ+dATwyolmxDU4YviB4 CD485eQ2RG865GItyQC+jO2K13LW0xStFtW/2mDspeDXwll7+7RMFrp7wAJVqIvOPB 3yxUZk54m4wYSUVjV/ZpEBfRxXXEMB2aVcfp87afwcWiqgJaFe1PFleNMQyyYcnIuO K6iyTtLE89a2gaj8ngxnXrUkrvnmoIUYwXrtSpIRfgZzJ33g4NEK+z4JXxJ7jUr7kd C+bsywMkeukpg== From: Miguel Ojeda To: Miguel Ojeda , Nathan Chancellor , Nicolas Schier , Danilo Krummrich , Andreas Hindborg , Catalin Marinas , Will Deacon , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Courbot , David Airlie , Simona Vetter , Brendan Higgins , David Gow , Greg Kroah-Hartman , =?UTF-8?q?Arve=20Hj=C3=B8nnev=C3=A5g?= , Todd Kjos , Christian Brauner , Carlos Llamas , Alice Ryhl , Jonathan Corbet Cc: Boqun Feng , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Benno Lossin , Trevor Gross , rust-for-linux@vger.kernel.org, linux-kbuild@vger.kernel.org, Lorenzo Stoakes , Vlastimil Babka , "Liam R . Howlett" , Uladzislau Rezki , linux-block@vger.kernel.org, linux-arm-kernel@lists.infradead.org (moderated for non-subscribers), Alexandre Ghiti , linux-riscv@lists.infradead.org, nouveau@lists.freedesktop.org, dri-devel@lists.freedesktop.org, Rae Moar , linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com, Nick Desaulniers , Bill Wendling , Justin Stitt , llvm@lists.linux.dev, linux-kernel@vger.kernel.org, Shuah Khan , linux-doc@vger.kernel.org Subject: [PATCH 05/33] rust: remove `RUSTC_HAS_COERCE_POINTEE` and simplify code Date: Wed, 1 Apr 2026 13:45:12 +0200 Message-ID: <20260401114540.30108-6-ojeda@kernel.org> In-Reply-To: <20260401114540.30108-1-ojeda@kernel.org> References: <20260401114540.30108-1-ojeda@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" With the Rust version bump in place, the `RUSTC_HAS_COERCE_POINTEE` Kconfig (automatic) option is always true. Thus remove the option and simplify the code. In particular, this includes removing our use of the predecessor unstable features we used with Rust < 1.84.0 (`coerce_unsized`, `dispatch_from_dyn` and `unsize`). Signed-off-by: Miguel Ojeda Acked-by: Danilo Krummrich Reviewed-by: Gary Guo --- init/Kconfig | 3 --- rust/kernel/alloc/kbox.rs | 29 ++--------------------------- rust/kernel/lib.rs | 8 +------- rust/kernel/list/arc.rs | 22 +--------------------- rust/kernel/sync/arc.rs | 21 ++------------------- 5 files changed, 6 insertions(+), 77 deletions(-) diff --git a/init/Kconfig b/init/Kconfig index c38f49228157..f9fac458e4d4 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -178,9 +178,6 @@ config LD_CAN_USE_KEEP_IN_OVERLAY # https://github.com/llvm/llvm-project/pull/130661 def_bool LD_IS_BFD || LLD_VERSION >=3D 210000 =20 -config RUSTC_HAS_COERCE_POINTEE - def_bool RUSTC_VERSION >=3D 108400 - config RUSTC_HAS_SPAN_FILE def_bool RUSTC_VERSION >=3D 108800 =20 diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs index 622b3529edfc..bd6da02c7ab8 100644 --- a/rust/kernel/alloc/kbox.rs +++ b/rust/kernel/alloc/kbox.rs @@ -77,33 +77,8 @@ /// `self.0` is always properly aligned and either points to memory alloca= ted with `A` or, for /// zero-sized types, is a dangling, well aligned pointer. #[repr(transparent)] -#[cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, derive(core::marker::CoercePoi= ntee))] -pub struct Box<#[cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, pointee)] T: ?S= ized, A: Allocator>( - NonNull, - PhantomData, -); - -// This is to allow coercion from `Box` to `Box` if `T` can be= converted to the -// dynamically-sized type (DST) `U`. -#[cfg(not(CONFIG_RUSTC_HAS_COERCE_POINTEE))] -impl core::ops::CoerceUnsized> for Box -where - T: ?Sized + core::marker::Unsize, - U: ?Sized, - A: Allocator, -{ -} - -// This is to allow `Box` to be dispatched on when `Box` can b= e coerced into `Box`. -#[cfg(not(CONFIG_RUSTC_HAS_COERCE_POINTEE))] -impl core::ops::DispatchFromDyn> for Box -where - T: ?Sized + core::marker::Unsize, - U: ?Sized, - A: Allocator, -{ -} +#[derive(core::marker::CoercePointee)] +pub struct Box<#[pointee] T: ?Sized, A: Allocator>(NonNull, PhantomData= ); =20 /// Type alias for [`Box`] with a [`Kmalloc`] allocator. /// diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 621cae75030c..66a09d77a2c4 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -39,17 +39,11 @@ // // Expected to become stable. #![feature(arbitrary_self_types)] +#![feature(derive_coerce_pointee)] // // To be determined. #![feature(used_with_arg)] // -// `feature(derive_coerce_pointee)` is expected to become stable. Before R= ust -// 1.84.0, it did not exist, so enable the predecessor features. -#![cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, feature(derive_coerce_pointee= ))] -#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(coerce_unsized))] -#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(dispatch_from_dy= n))] -#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(unsize))] -// // `feature(file_with_nul)` is expected to become stable. Before Rust 1.89= .0, it did not exist, so // enable it conditionally. #![cfg_attr(CONFIG_RUSTC_HAS_FILE_WITH_NUL, feature(file_with_nul))] diff --git a/rust/kernel/list/arc.rs b/rust/kernel/list/arc.rs index e1082423909c..a9a2b0178f65 100644 --- a/rust/kernel/list/arc.rs +++ b/rust/kernel/list/arc.rs @@ -160,7 +160,7 @@ fn try_new_list_arc(&self) -> bool { /// /// [`List`]: crate::list::List #[repr(transparent)] -#[cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, derive(core::marker::CoercePoi= ntee))] +#[derive(core::marker::CoercePointee)] pub struct ListArc where T: ListArcSafe + ?Sized, @@ -443,26 +443,6 @@ fn as_ref(&self) -> &Arc { } } =20 -// This is to allow coercion from `ListArc` to `ListArc` if `T` can = be converted to the -// dynamically-sized type (DST) `U`. -#[cfg(not(CONFIG_RUSTC_HAS_COERCE_POINTEE))] -impl core::ops::CoerceUnsized> for Lis= tArc -where - T: ListArcSafe + core::marker::Unsize + ?Sized, - U: ListArcSafe + ?Sized, -{ -} - -// This is to allow `ListArc` to be dispatched on when `ListArc` can= be coerced into -// `ListArc`. -#[cfg(not(CONFIG_RUSTC_HAS_COERCE_POINTEE))] -impl core::ops::DispatchFromDyn> for L= istArc -where - T: ListArcSafe + core::marker::Unsize + ?Sized, - U: ListArcSafe + ?Sized, -{ -} - /// A utility for tracking whether a [`ListArc`] exists using an atomic. /// /// # Invariants diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index 921e19333b89..18d6c0d62ce0 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -128,7 +128,7 @@ /// # Ok::<(), Error>(()) /// ``` #[repr(transparent)] -#[cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, derive(core::marker::CoercePoi= ntee))] +#[derive(core::marker::CoercePointee)] pub struct Arc { ptr: NonNull>, // NB: this informs dropck that objects of type `ArcInner` may be u= sed in ` as @@ -182,15 +182,6 @@ unsafe fn container_of(ptr: *const T) -> NonNull> { } } =20 -// This is to allow coercion from `Arc` to `Arc` if `T` can be conve= rted to the -// dynamically-sized type (DST) `U`. -#[cfg(not(CONFIG_RUSTC_HAS_COERCE_POINTEE))] -impl, U: ?Sized> core::ops::CoerceUnsi= zed> for Arc {} - -// This is to allow `Arc` to be dispatched on when `Arc` can be coer= ced into `Arc`. -#[cfg(not(CONFIG_RUSTC_HAS_COERCE_POINTEE))] -impl, U: ?Sized> core::ops::DispatchFr= omDyn> for Arc {} - // SAFETY: It is safe to send `Arc` to another thread when the underlyi= ng `T` is `Sync` because // it effectively means sharing `&T` (which is safe because `T` is `Sync`)= ; additionally, it needs // `T` to be `Send` because any thread that has an `Arc` may ultimately= access `T` using a @@ -547,20 +538,12 @@ fn from(item: Pin>) -> Self { /// # Ok::<(), Error>(()) /// ``` #[repr(transparent)] -#[cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, derive(core::marker::CoercePoi= ntee))] +#[derive(core::marker::CoercePointee)] pub struct ArcBorrow<'a, T: ?Sized + 'a> { inner: NonNull>, _p: PhantomData<&'a ()>, } =20 -// This is to allow `ArcBorrow` to be dispatched on when `ArcBorrow`= can be coerced into -// `ArcBorrow`. -#[cfg(not(CONFIG_RUSTC_HAS_COERCE_POINTEE))] -impl, U: ?Sized> core::ops::DispatchFr= omDyn> - for ArcBorrow<'_, T> -{ -} - impl Clone for ArcBorrow<'_, T> { fn clone(&self) -> Self { *self --=20 2.53.0