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[103.168.172.201]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-6d35415a54csm15599906d6.103.2024.10.31.23.03.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 31 Oct 2024 23:03:52 -0700 (PDT) Received: from phl-compute-08.internal (phl-compute-08.phl.internal [10.202.2.48]) by mailfauth.phl.internal (Postfix) with ESMTP id A3CA61200043; Fri, 1 Nov 2024 02:03:51 -0400 (EDT) Received: from phl-mailfrontend-02 ([10.202.2.163]) by phl-compute-08.internal (MEProxy); Fri, 01 Nov 2024 02:03:51 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeeftddrvdekkedgkeekucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdggtfgfnhhsuhgsshgtrhhisggvpdfu rfetoffkrfgpnffqhgenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnh htshculddquddttddmnecujfgurhephffvvefufffkofgggfestdekredtredttdenucfh rhhomhepuehoqhhunhcuhfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrihhlrdgtoh hmqeenucggtffrrghtthgvrhhnpeeuieehffeijeelkeevheegleeifeevfeetkeehhfei ieevfeegvdelleekvdejleenucffohhmrghinhepkhgvrhhnvghlrdhorhhgpdhlfihnrd hnvghtpdhgihhthhhusgdrtghomhenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgr mhepmhgrihhlfhhrohhmpegsohhquhhnodhmvghsmhhtphgruhhthhhpvghrshhonhgrlh hithihqdeiledvgeehtdeigedqudejjeekheehhedvqdgsohhquhhnrdhfvghngheppehg mhgrihhlrdgtohhmsehfihigmhgvrdhnrghmvgdpnhgspghrtghpthhtohepheejpdhmoh guvgepshhmthhpohhuthdprhgtphhtthhopehruhhsthdqfhhorhdqlhhinhhugiesvhhg vghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehrtghusehvghgvrhdrkhgvrhhnvg hlrdhorhhgpdhrtghpthhtoheplhhinhhugidqkhgvrhhnvghlsehvghgvrhdrkhgvrhhn vghlrdhorhhgpdhrtghpthhtoheplhhinhhugidqrghrtghhsehvghgvrhdrkhgvrhhnvg hlrdhorhhgpdhrtghpthhtoheplhhlvhhmsehlihhsthhsrdhlihhnuhigrdguvghvpdhr tghpthhtoheplhhkmhhmsehlihhsthhsrdhlihhnuhigrdguvghvpdhrtghpthhtohepoh hjvggurgeskhgvrhhnvghlrdhorhhgpdhrtghpthhtoheprghlvgigrdhgrgihnhhorhes ghhmrghilhdrtghomhdprhgtphhtthhopeifvggushhonhgrfhesghhmrghilhdrtghomh X-ME-Proxy: Feedback-ID: iad51458e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Fri, 1 Nov 2024 02:03:51 -0400 (EDT) From: Boqun Feng To: rust-for-linux@vger.kernel.org, rcu@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, llvm@lists.linux.dev, lkmm@lists.linux.dev Cc: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Alan Stern , Andrea Parri , Will Deacon , Peter Zijlstra , Nicholas Piggin , David Howells , Jade Alglave , Luc Maranget , "Paul E. McKenney" , Akira Yokosawa , Daniel Lustig , Joel Fernandes , Nathan Chancellor , Nick Desaulniers , kent.overstreet@gmail.com, Greg Kroah-Hartman , elver@google.com, Mark Rutland , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Catalin Marinas , torvalds@linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, Trevor Gross , dakr@redhat.com, Frederic Weisbecker , Neeraj Upadhyay , Josh Triplett , Uladzislau Rezki , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Paul Walmsley , Palmer Dabbelt , Albert Ou , linux-riscv@lists.infradead.org Subject: [RFC v2 00/13] LKMM *generic* atomics in Rust Date: Thu, 31 Oct 2024 23:02:23 -0700 Message-ID: <20241101060237.1185533-1-boqun.feng@gmail.com> X-Mailer: git-send-email 2.45.2 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Hi, This is another RFC version of LKMM atomics in Rust, you can find the previous versions: v1: https://lore.kernel.org/rust-for-linux/20240612223025.1158537-1-boqun.feng@gmail.com/ wip: https://lore.kernel.org/rust-for-linux/20240322233838.868874-1-boqun.feng@gmail.com/ I add a few more people Cced this time, so if you're curious about why we choose to implement LKMM atomics instead of using the Rust ones, you can find some explanation: * In my Kangrejos talk: https://lwn.net/Articles/993785/ * In Linus' email: https://lore.kernel.org/rust-for-linux/CAHk-=whkQk=zq5XiMcaU3xj4v69+jyoP-y6Sywhq-TvxSSvfEA@mail.gmail.com/ This time, I try implementing a generic atomic type `Atomic`, since Benno and Gary suggested last time, and also Rust standard library is also going to that direction [1]. Honestly, a generic atomic type is still not quite necessary for myself, but here are a few reasons that it's useful: * It's useful for type alias, for example, if you have: type c_long = isize; Then `Atomic` and `Atomic` is the same type, this may make FFI code (mapping a C type to a Rust type or vice versa) more readable. * In kernel, we sometimes switch atomic to percpu for better scalabity, percpu is naturally a generic type, because it can have data that is larger than machine word size. Making atomic generic ease the potential switching/refactoring. * Generic atomics provide all the functionalities that non-generic atomics could have. That said, currently "generic" is limited to a few types: the type must be the same size as atomic_t or atomic64_t, other than basic types, only #[repr()] struct can be used in a `Atomic`. Also this is not a full feature set patchset, things like different arithmetic operations and bit operations are still missing, they can be either future work or for future versions. I included an RCU pointer implementation as one example of the usage, so a patch from Danilo is added, but I will drop it once his patch merged. This is based on today's rust-next, and I've run all kunit tests from the doc test on x86, arm64 and riscv. Feedbacks and comments are welcome! Thanks. Regards, Boqun [1]: https://github.com/rust-lang/rust/issues/130539 Boqun Feng (12): rust: Introduce atomic API helpers rust: sync: Add basic atomic operation mapping framework rust: sync: atomic: Add ordering annotation types rust: sync: atomic: Add generic atomics rust: sync: atomic: Add atomic {cmp,}xchg operations rust: sync: atomic: Add the framework of arithmetic operations rust: sync: atomic: Add Atomic rust: sync: atomic: Add Atomic<{usize,isize}> rust: sync: atomic: Add Atomic<*mut T> rust: sync: atomic: Add arithmetic ops for Atomic<*mut T> rust: sync: Add memory barriers rust: sync: rcu: Add RCU protected pointer Wedson Almeida Filho (1): rust: add rcu abstraction MAINTAINERS | 4 +- rust/helpers/atomic.c | 1038 +++++++++++++++++++++ rust/helpers/helpers.c | 3 + rust/helpers/rcu.c | 13 + rust/kernel/sync.rs | 3 + rust/kernel/sync/atomic.rs | 228 +++++ rust/kernel/sync/atomic/generic.rs | 516 ++++++++++ rust/kernel/sync/atomic/ops.rs | 199 ++++ rust/kernel/sync/atomic/ordering.rs | 94 ++ rust/kernel/sync/barrier.rs | 67 ++ rust/kernel/sync/rcu.rs | 319 +++++++ scripts/atomic/gen-atomics.sh | 1 + scripts/atomic/gen-rust-atomic-helpers.sh | 65 ++ 13 files changed, 2549 insertions(+), 1 deletion(-) create mode 100644 rust/helpers/atomic.c create mode 100644 rust/helpers/rcu.c create mode 100644 rust/kernel/sync/atomic.rs create mode 100644 rust/kernel/sync/atomic/generic.rs create mode 100644 rust/kernel/sync/atomic/ops.rs create mode 100644 rust/kernel/sync/atomic/ordering.rs create mode 100644 rust/kernel/sync/barrier.rs create mode 100644 rust/kernel/sync/rcu.rs create mode 100755 scripts/atomic/gen-rust-atomic-helpers.sh