Received-SPF: pass (google.com: domain of linux-kernel+bounces-112163-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Date: Fri, 22 Mar 2024 21:42:39 -0400
From: Kent Overstreet <kent.overstreet@linux.dev>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, 
	linux-arch@vger.kernel.org, llvm@lists.linux.dev, Miguel Ojeda <ojeda@kernel.org>, 
	Alex Gaynor <alex.gaynor@gmail.com>, Wedson Almeida Filho <wedsonaf@gmail.com>, 
	Gary Guo <gary@garyguo.net>, =?utf-8?B?QmrDtnJu?= Roy Baron <bjorn3_gh@protonmail.com>, 
	Benno Lossin <benno.lossin@proton.me>, Andreas Hindborg <a.hindborg@samsung.com>, 
	Alice Ryhl <aliceryhl@google.com>, Alan Stern <stern@rowland.harvard.edu>, 
	Andrea Parri <parri.andrea@gmail.com>, Will Deacon <will@kernel.org>, 
	Peter Zijlstra <peterz@infradead.org>, Nicholas Piggin <npiggin@gmail.com>, 
	David Howells <dhowells@redhat.com>, Jade Alglave <j.alglave@ucl.ac.uk>, 
	Luc Maranget <luc.maranget@inria.fr>, "Paul E. McKenney" <paulmck@kernel.org>, 
	Akira Yokosawa <akiyks@gmail.com>, Daniel Lustig <dlustig@nvidia.com>, 
	Joel Fernandes <joel@joelfernandes.org>, Nathan Chancellor <nathan@kernel.org>, 
	Nick Desaulniers <ndesaulniers@google.com>, kent.overstreet@gmail.com, 
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>, elver@google.com, Mark Rutland <mark.rutland@arm.com>, 
	Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, 
	Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>, 
	Catalin Marinas <catalin.marinas@arm.com>, torvalds@linux-foundation.org, 
	linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org
Subject: Re: [WIP 0/3] Memory model and atomic API in Rust
Message-ID: <v7gcnb6a3kqolyx6jrusburtwhsnomg543jpulza233bjofesl@zrunbxkpaa2n>
References: <20240322233838.868874-1-boqun.feng@gmail.com>
 <s2jeqq22n5ef5jknaps37mfdjvuqrns4w7i22qp2r7r4bzjqs2@my3eyxoa3pl3>
 <Zf4fDJNBeRN5HOYo@boqun-archlinux>
 <Zf4nE_AvHPx9F2nQ@boqun-archlinux>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <Zf4nE_AvHPx9F2nQ@boqun-archlinux>

On Fri, Mar 22, 2024 at 05:49:23PM -0700, Boqun Feng wrote:
> On Fri, Mar 22, 2024 at 05:15:08PM -0700, Boqun Feng wrote:
> [...]
> > > 
> > > I wonder about that. The disadvantage of only supporting LKMM atomics is
> > > that we'll be incompatible with third party code, and we don't want to
> > > be rolling all of our own data structures forever.
> > > 
> > 
> > A possible solution to that is a set of C++ memory model atomics
> > implemented by LKMM atomics. That should be possible.
> > 
> 
> Another possible "solution" works in the opposite direction, since the
> folder rust/kernel/sync/atomic is quite stand-alone, we can export that
> as a Rust crate (library), and third party code can support using LKMM
> atomics instead of Rust own atomics ;-) Of course if the project is
> supposed to work with Linux kernel.

Not just from the Rust side, the C side would be useful as well. I've
got a quicky, dirty, hacky version of that in bcachefs-tools, and I
would switch immediately if someone took that over and made it a real
project, and I'm quite sure other projects would as well.