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[103.168.172.201]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8907724ef8fsm115115876d6.42.2026.01.11.04.03.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 11 Jan 2026 04:03:03 -0800 (PST) Received: from phl-compute-05.internal (phl-compute-05.internal [10.202.2.45]) by mailfauth.phl.internal (Postfix) with ESMTP id AB1B0F40068; Sun, 11 Jan 2026 07:03:02 -0500 (EST) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-05.internal (MEProxy); Sun, 11 Jan 2026 07:03:02 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefgedrtddtgdduudeghedvucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceu rghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujf gurhephffvvefufffkofgjfhgggfestdekredtredttdenucfhrhhomhepuehoqhhunhcu hfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrihhlrdgtohhmqeenucggtffrrghtth gvrhhnpedvveekvddtffelffelfedvudefffeuheejgeeivedufffgledvgeduveffueeh leenucffohhmrghinhepmhhsghhiugdrlhhinhhknecuvehluhhsthgvrhfuihiivgepvd enucfrrghrrghmpehmrghilhhfrhhomhepsghoqhhunhdomhgvshhmthhprghuthhhphgv rhhsohhnrghlihhthidqieelvdeghedtieegqddujeejkeehheehvddqsghoqhhunhdrfh gvnhhgpeepghhmrghilhdrtghomhesfhhigihmvgdrnhgrmhgvpdhnsggprhgtphhtthho peduhedpmhhouggvpehsmhhtphhouhhtpdhrtghpthhtohepphgvthgvrhiisehinhhfrh gruggvrggurdhorhhgpdhrtghpthhtohepmhhinhhgoheskhgvrhhnvghlrdhorhhgpdhr tghpthhtoheprhhushhtqdhfohhrqdhlihhnuhigsehvghgvrhdrkhgvrhhnvghlrdhorh hgpdhrtghpthhtoheplhhinhhugidqkhgvrhhnvghlsehvghgvrhdrkhgvrhhnvghlrdho rhhgpdhrtghpthhtohepfihilhhlsehkvghrnhgvlhdrohhrghdprhgtphhtthhopehmrg hrkhdrrhhuthhlrghnugesrghrmhdrtghomhdprhgtphhtthhopehtghhlgieslhhinhhu thhrohhnihigrdguvgdprhgtphhtthhopehojhgvuggrsehkvghrnhgvlhdrohhrghdprh gtphhtthhopehgrghrhiesghgrrhihghhuohdrnhgvth X-ME-Proxy: Feedback-ID: iad51458e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Sun, 11 Jan 2026 07:03:02 -0500 (EST) From: Boqun Feng To: "Peter Zijlstra" , "Ingo Molnar" Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, "Will Deacon" , "Mark Rutland" , "Thomas Gleixner" , "Miguel Ojeda" , "Gary Guo" , "Alice Ryhl" , "Andreas Hindborg" , "Benno Lossin" , "Danilo Krummrich" , FUJITA Tomonori , Boqun Feng Subject: [PATCH 19/36] rust: sync: atomic: Add i8/i16 xchg and cmpxchg support Date: Sun, 11 Jan 2026 20:01:52 +0800 Message-ID: <20260111120209.6133-17-boqun.feng@gmail.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260111120209.6133-1-boqun.feng@gmail.com> References: <20260111115808.5702-1-boqun.feng@gmail.com> <20260111120209.6133-1-boqun.feng@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: FUJITA Tomonori Add atomic xchg and cmpxchg operation support for i8 and i16 types with tests. Note that since the current implementation of Atomic::<{i8,i16}>::{load,store}() is READ_ONCE()/WRITE_ONCE()-based. The atomicity between load/store and xchg/cmpxchg is only guaranteed if the architecture has native RmW support, hence i8/i16 is currently AtomicImpl only when CONFIG_ARCH_SUPPORTS_ATOMIC_RWM=y. [boqun: Make i8/i16 AtomicImpl only when CONFIG_ARCH_SUPPORTS_ATOMIC_RWM=y] Signed-off-by: FUJITA Tomonori Signed-off-by: Boqun Feng Link: https://patch.msgid.link/20251228120546.1602275-4-fujita.tomonori@gmail.com --- rust/kernel/sync/atomic/internal.rs | 8 +++++++- rust/kernel/sync/atomic/predefine.rs | 4 ++-- 2 files changed, 9 insertions(+), 3 deletions(-) diff --git a/rust/kernel/sync/atomic/internal.rs b/rust/kernel/sync/atomic/internal.rs index 1b2a7933bc14..0dac58bca2b3 100644 --- a/rust/kernel/sync/atomic/internal.rs +++ b/rust/kernel/sync/atomic/internal.rs @@ -37,10 +37,16 @@ pub trait AtomicImpl: Sized + Send + Copy + private::Sealed { type Delta; } +// The current helpers of load/store uses `{WRITE,READ}_ONCE()` hence the atomicity is only +// guaranteed against read-modify-write operations if the architecture supports native atomic RmW. +#[cfg(CONFIG_ARCH_SUPPORTS_ATOMIC_RMW)] impl AtomicImpl for i8 { type Delta = Self; } +// The current helpers of load/store uses `{WRITE,READ}_ONCE()` hence the atomicity is only +// guaranteed against read-modify-write operations if the architecture supports native atomic RmW. +#[cfg(CONFIG_ARCH_SUPPORTS_ATOMIC_RMW)] impl AtomicImpl for i16 { type Delta = Self; } @@ -274,7 +280,7 @@ fn set[release](a: &AtomicRepr, v: Self) { ); declare_and_impl_atomic_methods!( - [ i32 => atomic, i64 => atomic64 ] + [ i8 => atomic_i8, i16 => atomic_i16, i32 => atomic, i64 => atomic64 ] /// Exchange and compare-and-exchange atomic operations pub trait AtomicExchangeOps { /// Atomic exchange. diff --git a/rust/kernel/sync/atomic/predefine.rs b/rust/kernel/sync/atomic/predefine.rs index 51e9df0cf56e..248d26555ccf 100644 --- a/rust/kernel/sync/atomic/predefine.rs +++ b/rust/kernel/sync/atomic/predefine.rs @@ -149,7 +149,7 @@ fn atomic_acquire_release_tests() { #[test] fn atomic_xchg_tests() { - for_each_type!(42 in [i32, i64, u32, u64, isize, usize] |v| { + for_each_type!(42 in [i8, i16, i32, i64, u32, u64, isize, usize] |v| { let x = Atomic::new(v); let old = v; @@ -162,7 +162,7 @@ fn atomic_xchg_tests() { #[test] fn atomic_cmpxchg_tests() { - for_each_type!(42 in [i32, i64, u32, u64, isize, usize] |v| { + for_each_type!(42 in [i8, i16, i32, i64, u32, u64, isize, usize] |v| { let x = Atomic::new(v); let old = v; -- 2.51.0