From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sender4-pp-f112.zoho.com (sender4-pp-f112.zoho.com [136.143.188.112]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D79C01CA84; Tue, 19 Aug 2025 18:33:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=pass smtp.client-ip=136.143.188.112 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755628384; cv=pass; b=ABnNZ+YsTaK5dWubH7vXmgY/niak6MxPREWOD5ZNJZNdfzaKWjiZzQTNtBuATha/UkXr9q0XrHzXA+GtCF3Yekn4E+rfJwmjyYjhhji6cvgCib7UIL+oWGq0235Gup3DZOyo/7FDdMqV9d/USEi+t1o+1bT3XYm6JhDLiht8gMs= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755628384; c=relaxed/simple; bh=gyCnc6XMMEZwjfpHHn3fsXLulNzAZSiJEyyQg0iCnMg=; h=Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc: Message-Id:References:To; b=ujqB+qNagvqMOsB6z5gQ96EmkfTNKf/ZN8vruMWnmbHmsQbcCxgbLurGvdy6PQXPQoVtS2rxpxGwXOkJd0NHb3m0tQC3VnFsO5+0Ju2mB7VWp+4x7u40uPJP0b5n37KOJF1AMY/patBIucy4XvWz2HvkxwT1Hnv8DXq+QnxA8XI= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (1024-bit key) header.d=collabora.com header.i=daniel.almeida@collabora.com header.b=TAo7dedv; arc=pass smtp.client-ip=136.143.188.112 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=collabora.com header.i=daniel.almeida@collabora.com header.b="TAo7dedv" ARC-Seal: i=1; a=rsa-sha256; t=1755628362; cv=none; d=zohomail.com; s=zohoarc; b=aI3xGS1ywG/MLi87Bh0Z2bqBzAQ2TAly8SPdHGfJDXxItqPHGvvVIoKDMhjQSqfD4feEAgLWi7McrpRfVHit5U8E3PfR0TbjURP+rK08n3AjreDZGUN/rfjQYUcYDJM8g3/BU1u3sufW67kgozzW5mt0/4tZxiI90TM2OAcdEj4= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1755628362; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=BEtAilB2KNZcvq6SvOa/0+TPx2JcL1FpO0Zea2H+S9M=; b=kzO+9XoNkLi7gJfbJWsKFa9cBDLclS9X/q6CfT9qLryD1Qt7Gq6fmiU0itrf7xyLmR+IcczzLs7BOa1u8aNgWZeuBkLE9elWxm2a+7iicCfPBB1IrkjFLJq41VJVQLsbo7fK0KGaHeJxDK3Rai+jXldBbw7GJWMKmX5+QhDLsD8= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=daniel.almeida@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1755628362; s=zohomail; d=collabora.com; i=daniel.almeida@collabora.com; h=Content-Type:Mime-Version:Subject:Subject:From:From:In-Reply-To:Date:Date:Cc:Cc:Content-Transfer-Encoding:Message-Id:Message-Id:References:To:To:Reply-To; bh=BEtAilB2KNZcvq6SvOa/0+TPx2JcL1FpO0Zea2H+S9M=; b=TAo7dedvqPN8b/rP80FSF+rePxIzJa7twCTNAAamuAoAvuU3uU+zjiu0Ce9mwf3Y fF5Igh8vO0nHk0zA2aIf+k+qrM9pQL05v9sGk2QQu71f/3Wx6cIp8NI+Y5sIvcsztke x7cXpxisVrBsW7h27fKGSv1cIM5DbkAIVL9dzrBQ= Received: by mx.zohomail.com with SMTPS id 1755628360586610.4093312458549; Tue, 19 Aug 2025 11:32:40 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3826.700.81\)) Subject: Re: [PATCH v2 1/2] rust: Add cpu_relax() helper From: Daniel Almeida In-Reply-To: <20250817044724.3528968-2-fujita.tomonori@gmail.com> Date: Tue, 19 Aug 2025 15:32:23 -0300 Cc: a.hindborg@kernel.org, alex.gaynor@gmail.com, ojeda@kernel.org, aliceryhl@google.com, anna-maria@linutronix.de, bjorn3_gh@protonmail.com, boqun.feng@gmail.com, dakr@kernel.org, frederic@kernel.org, gary@garyguo.net, jstultz@google.com, linux-kernel@vger.kernel.org, lossin@kernel.org, lyude@redhat.com, rust-for-linux@vger.kernel.org, sboyd@kernel.org, tglx@linutronix.de, tmgross@umich.edu, acourbot@nvidia.com Content-Transfer-Encoding: quoted-printable Message-Id: <843AC662-BBC0-4879-A5F8-68C41C660A59@collabora.com> References: <20250817044724.3528968-1-fujita.tomonori@gmail.com> <20250817044724.3528968-2-fujita.tomonori@gmail.com> To: FUJITA Tomonori X-Mailer: Apple Mail (2.3826.700.81) X-ZohoMailClient: External > On 17 Aug 2025, at 01:47, FUJITA Tomonori = wrote: >=20 > Add cpu_relax() helper in preparation for supporting > read_poll_timeout(). >=20 > Reviewed-by: Alice Ryhl > Reviewed-by: Andreas Hindborg > Signed-off-by: FUJITA Tomonori > --- > rust/helpers/helpers.c | 1 + > rust/helpers/processor.c | 8 ++++++++ > rust/kernel/lib.rs | 1 + > rust/kernel/processor.rs | 14 ++++++++++++++ > 4 files changed, 24 insertions(+) > create mode 100644 rust/helpers/processor.c > create mode 100644 rust/kernel/processor.rs >=20 > diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c > index 7cf7fe95e41d..04598665e7c8 100644 > --- a/rust/helpers/helpers.c > +++ b/rust/helpers/helpers.c > @@ -34,6 +34,7 @@ > #include "pid_namespace.c" > #include "platform.c" > #include "poll.c" > +#include "processor.c" > #include "property.c" > #include "rbtree.c" > #include "rcu.c" > diff --git a/rust/helpers/processor.c b/rust/helpers/processor.c > new file mode 100644 > index 000000000000..d41355e14d6e > --- /dev/null > +++ b/rust/helpers/processor.c > @@ -0,0 +1,8 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#include > + > +void rust_helper_cpu_relax(void) > +{ > + cpu_relax(); > +} > diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs > index ed53169e795c..c098c47c1817 100644 > --- a/rust/kernel/lib.rs > +++ b/rust/kernel/lib.rs > @@ -110,6 +110,7 @@ > pub mod platform; > pub mod prelude; > pub mod print; > +pub mod processor; > pub mod rbtree; > pub mod regulator; > pub mod revocable; > diff --git a/rust/kernel/processor.rs b/rust/kernel/processor.rs > new file mode 100644 > index 000000000000..85b49b3614dd > --- /dev/null > +++ b/rust/kernel/processor.rs > @@ -0,0 +1,14 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +//! Processor related primitives. > +//! > +//! C header: = [`include/linux/processor.h`](srctree/include/linux/processor.h) > + > +/// Lower CPU power consumption or yield to a hyperthreaded twin = processor. > +/// > +/// It also happens to serve as a compiler barrier. > +#[inline] > +pub fn cpu_relax() { > + // SAFETY: Always safe to call. > + unsafe { bindings::cpu_relax() } > +} > --=20 > 2.43.0 >=20 >=20 Reviewed-by: Daniel Almeida =