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[103.168.172.201]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8942e6031b4sm93625526d6.15.2026.01.19.18.56.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Jan 2026 18:56:12 -0800 (PST) Received: from phl-compute-10.internal (phl-compute-10.internal [10.202.2.50]) by mailfauth.phl.internal (Postfix) with ESMTP id 9A98DF4006A; Mon, 19 Jan 2026 21:56:11 -0500 (EST) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-10.internal (MEProxy); Mon, 19 Jan 2026 21:56:11 -0500 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeefgedrtddtgddufeelvdekucetufdoteggodetrf dotffvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfurfetoffkrfgpnffqhgenuceu rghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujf gurhepfffhvfevuffkfhggtggujgesthdtredttddtvdenucfhrhhomhepuehoqhhunhcu hfgvnhhguceosghoqhhunhdrfhgvnhhgsehgmhgrihhlrdgtohhmqeenucggtffrrghtth gvrhhnpeehudfgudffffetuedtvdehueevledvhfelleeivedtgeeuhfegueevieduffei vdenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpegsoh hquhhnodhmvghsmhhtphgruhhthhhpvghrshhonhgrlhhithihqdeiledvgeehtdeigedq udejjeekheehhedvqdgsohhquhhnrdhfvghngheppehgmhgrihhlrdgtohhmsehfihigmh gvrdhnrghmvgdpnhgspghrtghpthhtohepudegpdhmohguvgepshhmthhpohhuthdprhgt phhtthhopehfuhhjihhtrgdrthhomhhonhhorhhisehgmhgrihhlrdgtohhmpdhrtghpth htohepohhjvggurgeskhgvrhhnvghlrdhorhhgpdhrtghpthhtohepphgvthgvrhiisehi nhhfrhgruggvrggurdhorhhgpdhrtghpthhtohepfihilhhlsehkvghrnhgvlhdrohhrgh dprhgtphhtthhopegrrdhhihhnuggsohhrgheskhgvrhhnvghlrdhorhhgpdhrtghpthht oheprghlihgtvghrhihhlhesghhoohhglhgvrdgtohhmpdhrtghpthhtohepsghjohhrnh efpghghhesphhrohhtohhnmhgrihhlrdgtohhmpdhrtghpthhtohepuggrkhhrsehkvghr nhgvlhdrohhrghdprhgtphhtthhopehgrghrhiesghgrrhihghhuohdrnhgvth X-ME-Proxy: Feedback-ID: iad51458e:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Mon, 19 Jan 2026 21:56:11 -0500 (EST) Date: Tue, 20 Jan 2026 10:56:09 +0800 From: Boqun Feng To: FUJITA Tomonori Cc: ojeda@kernel.org, peterz@infradead.org, will@kernel.org, a.hindborg@kernel.org, aliceryhl@google.com, bjorn3_gh@protonmail.com, dakr@kernel.org, gary@garyguo.net, lossin@kernel.org, mark.rutland@arm.com, tmgross@umich.edu, rust-for-linux@vger.kernel.org Subject: Re: [PATCH v4 1/2] rust: sync: atomic: Add performance-optimal-integer-backed Flag for atomic booleans Message-ID: References: <20260115021230.3297420-2-fujita.tomonori@gmail.com> <20260119.121025.255021656975699898.fujita.tomonori@gmail.com> <20260120.080851.1721614339637284826.fujita.tomonori@gmail.com> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260120.080851.1721614339637284826.fujita.tomonori@gmail.com> On Tue, Jan 20, 2026 at 08:08:51AM +0900, FUJITA Tomonori wrote: > On Mon, 19 Jan 2026 12:10:25 +0900 (JST) > FUJITA Tomonori wrote: > > > On Mon, 19 Jan 2026 09:22:10 +0800 > > Boqun Feng wrote: > > > >> On Thu, Jan 15, 2026 at 11:12:29AM +0900, FUJITA Tomonori wrote: > >>> Add a new Flag enum (Clear/Set) and implement AtomicType for it, so > >>> users can use Atomic for boolean flags. > >>> > >>> The backing integer type is an implementation detail; it may vary by > >>> architecture and change in the future. > >>> > >>> Document when Atomic is generally preferable to Atomic: in > >>> particular, when RMW operations such as xchg()/cmpxchg() may be used > >>> and minimizing memory usage is not the top priority. On some > >>> architectures without byte-sized RMW instructions, Atomic can be > >>> slower for RMW operations. > >>> > >>> Signed-off-by: FUJITA Tomonori > >>> --- > >>> rust/kernel/sync/atomic.rs | 71 ++++++++++++++++++++++++++++++++++++++ > >>> 1 file changed, 71 insertions(+) > >>> > >>> diff --git a/rust/kernel/sync/atomic.rs b/rust/kernel/sync/atomic.rs > >>> index ca9cab77abf0..58f57903460f 100644 > >>> --- a/rust/kernel/sync/atomic.rs > >>> +++ b/rust/kernel/sync/atomic.rs > >> > >> I prefer we can move `Flag` into atomic/predefine.rs, I queued in > >> rust-sync with the following version, please let me know whether it > >> works, thank you all! > > > > Works for me, thanks! > > If we like to keep the intra-doc-links, a workaround like the > followings seems to be necessary. > > diff --git a/rust/kernel/sync/atomic/predefine.rs b/rust/kernel/sync/atomic/predefine.rs > index f6c7538cb47b..92e312c06595 100644 > --- a/rust/kernel/sync/atomic/predefine.rs > +++ b/rust/kernel/sync/atomic/predefine.rs > @@ -156,6 +156,13 @@ fn rhs_into_delta(rhs: usize) -> isize_atomic_repr { > /// flag.store(Flag::Set, Relaxed); > /// assert_eq!(Flag::Set, flag.load(Relaxed)); > /// ``` > +/// > +/// [`Atomic`]: kernel::sync::atomic::Atomic > +/// [`Atomic`]: kernel::sync::atomic::Atomic > +/// [`Atomic::xchg()`]: kernel::sync::atomic::Atomic::xchg > +/// [`Atomic::cmpxchg()`]: kernel::sync::atomic::Atomic::cmpxchg > +/// [`Atomic::load()`]: kernel::sync::atomic::Atomic::load > +/// [`Atomic::store()`]: kernel::sync::atomic::Atomic::store > #[derive(Clone, Copy, PartialEq, Eq)] > #[cfg_attr(any(CONFIG_X86_64, CONFIG_UML, CONFIG_ARM, CONFIG_ARM64), repr(i8))] > #[cfg_attr( > Good point! I was missing that, however I think we could use `super` instead of `kernel::sync::atomic` in this case. Already pushed to rust-sync with the following changes, thanks! Regards, Boqun ------------->8 diff --git a/rust/kernel/sync/atomic/predefine.rs b/rust/kernel/sync/atomic/predefine.rs index f6c7538cb47b..5faa2fe2f4b6 100644 --- a/rust/kernel/sync/atomic/predefine.rs +++ b/rust/kernel/sync/atomic/predefine.rs @@ -156,6 +156,13 @@ fn rhs_into_delta(rhs: usize) -> isize_atomic_repr { /// flag.store(Flag::Set, Relaxed); /// assert_eq!(Flag::Set, flag.load(Relaxed)); /// ``` +/// +/// [`Atomic`]: super::Atomic +/// [`Atomic`]: super::Atomic +/// [`Atomic::xchg()`]: super::Atomic::xchg +/// [`Atomic::cmpxchg()`]: super::Atomic::cmpxchg +/// [`Atomic::load()`]: super::Atomic::load +/// [`Atomic::store()`]: super::Atomic::store #[derive(Clone, Copy, PartialEq, Eq)] #[cfg_attr(any(CONFIG_X86_64, CONFIG_UML, CONFIG_ARM, CONFIG_ARM64), repr(i8))] #[cfg_attr(