linux-kernel - Re: [PATCH 4/5] rust: sync: atomic: Add Atomic<*mut T> support

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Message-Id: <20260119.120934.33535744184163382.fujita.tomonori@gmail.com>
Date: Mon, 19 Jan 2026 12:09:34 +0900 (JST)
From: FUJITA Tomonori <fujita.tomonori@...il.com>
To: boqun.feng@...il.com
Cc: rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org,
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Subject: Re: [PATCH 4/5] rust: sync: atomic: Add Atomic<*mut T> support

On Sat, 17 Jan 2026 20:22:42 +0800
Boqun Feng <boqun.feng@...il.com> wrote:

> Atomic pointer support is an important piece of synchronization
> algorithm, e.g. RCU, hence provide the support for that.
> 
> Note that instead of relying on atomic_long or the implementation of
> `Atomic<usize>`, a new set of helpers (atomic_ptr_*) is introduced for
> atomic pointer specifically, this is because ptr2int casting would
> lose the provenance of a pointer and even though in theory there are a
> few tricks the provenance can be restored, it'll still be a simpler
> implementation if C could provide atomic pointers directly. The side
> effects of this approach are: we don't have the arithmetic and logical
> operations for pointers yet and the current implementation only works
> on ARCH_SUPPORTS_ATOMIC_RMW architectures, but these are implementation
> issues and can be added later.
> 
> Signed-off-by: Boqun Feng <boqun.feng@...il.com>
> ---
>  rust/helpers/atomic_ext.c            |  3 +++
>  rust/kernel/sync/atomic.rs           | 12 +++++++++++-
>  rust/kernel/sync/atomic/internal.rs  | 21 +++++++++++++++------
>  rust/kernel/sync/atomic/predefine.rs | 23 +++++++++++++++++++++++
>  4 files changed, 52 insertions(+), 7 deletions(-)

Reviewed-by: FUJITA Tomonori <fujita.tomonori@...il.com>