linux-kernel - Re: [PATCH v5 05/10] rust: sync: atomic: Add atomic {cmp,}xchg operations

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aGKsHZ0saC-XkQlA@tardis-2.local>
Date: Mon, 30 Jun 2025 08:24:13 -0700
From: Boqun Feng <boqun.feng@...il.com>
To: Benno Lossin <lossin@...nel.org>
Cc: linux-kernel@...r.kernel.org, rust-for-linux@...r.kernel.org,
	lkmm@...ts.linux.dev, linux-arch@...r.kernel.org,
	Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>, Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>,
	Danilo Krummrich <dakr@...nel.org>, Will Deacon <will@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Mark Rutland <mark.rutland@....com>,
	Wedson Almeida Filho <wedsonaf@...il.com>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Lyude Paul <lyude@...hat.com>, Ingo Molnar <mingo@...nel.org>,
	Mitchell Levy <levymitchell0@...il.com>,
	"Paul E. McKenney" <paulmck@...nel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v5 05/10] rust: sync: atomic: Add atomic {cmp,}xchg
 operations

On Sat, Jun 28, 2025 at 10:00:34AM +0200, Benno Lossin wrote:
> On Sat Jun 28, 2025 at 9:31 AM CEST, Boqun Feng wrote:
> > On Sat, Jun 28, 2025 at 08:12:42AM +0200, Benno Lossin wrote:
> >> On Fri Jun 27, 2025 at 3:53 PM CEST, Boqun Feng wrote:
> >> > As for naming, the reason I choose xchg() and cmpxchg() is because they
> >> > are the name LKMM uses for a long time, to use another name, we have to
> >> > have a very good reason to do so and I don't see a good reason
> >> > that the other names are better, especially, in our memory model, we use
> >> > xchg() and cmpxchg() a lot, and they are different than Rust version
> >> > where you can specify orderings separately. Naming LKMM xchg()/cmpxchg()
> >> > would cause more confusion I believe.
> >> 
> >> I'm just not used to the name shortening from the kernel... I think it's
> >
> > I guess it's a bit curse of knowledge from my side...
> >
> >> fine to use them especially since the ordering parameters differ from
> >> std's atomics.
> >> 
> >> Can you add aliases for the Rust names?
> >> 
> >
> > I can, but I also want to see a real user request ;-) As a bi-model user
> > myself, I generally don't mind the name, as you can see C++ and Rust use
> > different names as well, what I usually do is just "tell me what's the
> > name of the function if I need to do this" ;-)
> 
> I think learning Rust in the kernel is different from learning a new
> language. Yes you're learning a specific dialect of Rust, but that's
> what every project does.
> 
> You also added aliases for the C versions, so let's also add the Rust
> ones :)
> 

Make senses, so added:

--- a/rust/kernel/sync/atomic/generic.rs
+++ b/rust/kernel/sync/atomic/generic.rs
@@ -310,7 +310,7 @@ impl<T: AllowAtomic> Atomic<T>
     /// assert_eq!(42, x.xchg(52, Acquire));
     /// assert_eq!(52, x.load(Relaxed));
     /// ```
-    #[doc(alias("atomic_xchg", "atomic64_xchg"))]
+    #[doc(alias("atomic_xchg", "atomic64_xchg", "swap"))]
     #[inline(always)]
     pub fn xchg<Ordering: Any>(&self, v: T, _: Ordering) -> T {
         let v = T::into_repr(v);
@@ -382,6 +382,7 @@ pub fn xchg<Ordering: Any>(&self, v: T, _: Ordering) -> T {
         "atomic64_cmpxchg",
         "atomic_try_cmpxchg",
         "atomic64_try_cmpxchg"
+        "compare_exchange"
     ))]
     #[inline(always)]
     pub fn cmpxchg<Ordering: Any>(&self, mut old: T, new: T, o: Ordering) -> Result<T, T> {

Seems good?

Regards,
Boqun