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[180.34.120.7]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-245ed50352esm37464065ad.128.2025.08.20.17.21.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Aug 2025 17:21:59 -0700 (PDT) From: FUJITA Tomonori To: a.hindborg@kernel.org, alex.gaynor@gmail.com, ojeda@kernel.org Cc: 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, daniel.almeida@collabora.com Subject: [PATCH v3 1/2] rust: Add cpu_relax() helper Date: Thu, 21 Aug 2025 09:20:54 +0900 Message-ID: <20250821002055.3654160-2-fujita.tomonori@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250821002055.3654160-1-fujita.tomonori@gmail.com> References: <20250821002055.3654160-1-fujita.tomonori@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: quoted-printable Content-Type: text/plain; charset="utf-8" Add cpu_relax() helper in preparation for supporting read_poll_timeout(). Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg Reviewed-by: Daniel Almeida Signed-off-by: FUJITA Tomonori Acked-by: Miguel Ojeda --- 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 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/processo= r.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