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Message-Id: <d5a3b9b2838df8dcf4769841e7a21a647d7f6247.1740726226.git.viresh.kumar@linaro.org>
Date: Fri, 28 Feb 2025 13:26:46 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Yury Norov <yury.norov@...il.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>,
Viresh Kumar <viresh.kumar@...aro.org>,
Miguel Ojeda <ojeda@...nel.org>,
Alex Gaynor <alex.gaynor@...il.com>,
Boqun Feng <boqun.feng@...il.com>,
Gary Guo <gary@...yguo.net>,
Björn Roy Baron <bjorn3_gh@...tonmail.com>,
Benno Lossin <benno.lossin@...ton.me>,
Andreas Hindborg <a.hindborg@...nel.org>,
Alice Ryhl <aliceryhl@...gle.com>,
Trevor Gross <tmgross@...ch.edu>
Cc: linux-kernel@...r.kernel.org,
Danilo Krummrich <dakr@...hat.com>,
rust-for-linux@...r.kernel.org,
Vincent Guittot <vincent.guittot@...aro.org>,
Burak Emir <bqe@...gle.com>
Subject: [PATCH V2 1/2] rust: Add initial cpumask abstractions
Add initial Rust abstractions for struct cpumask, covering a subset of
its APIs. Additional APIs can be added as needed.
These abstractions will be used in upcoming Rust support for cpufreq and
OPP frameworks.
Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
---
rust/kernel/cpumask.rs | 209 +++++++++++++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 1 +
2 files changed, 210 insertions(+)
create mode 100644 rust/kernel/cpumask.rs
diff --git a/rust/kernel/cpumask.rs b/rust/kernel/cpumask.rs
new file mode 100644
index 000000000000..aa4919954c8c
--- /dev/null
+++ b/rust/kernel/cpumask.rs
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! CPU mask abstractions.
+//!
+//! C header: [`include/linux/cpumask.h`](srctree/include/linux/cpumask.h)
+
+use crate::{
+ alloc::{AllocError, Flags},
+ bindings,
+ prelude::*,
+ types::Opaque,
+};
+#[cfg(CONFIG_CPUMASK_OFFSTACK)]
+use core::ptr::{self, NonNull};
+
+#[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
+use core::mem::MaybeUninit;
+
+use core::ops::{Deref, DerefMut};
+
+/// This corresponds to the C type `struct cpumask`.
+#[repr(transparent)]
+pub struct Cpumask(Opaque<bindings::cpumask>);
+
+impl Cpumask {
+ /// Creates a mutable reference to an existing `struct cpumask` pointer.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime
+ /// of the returned reference.
+ pub unsafe fn from_raw_mut<'a>(ptr: *mut bindings::cpumask) -> &'a mut Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ unsafe { &mut *ptr.cast() }
+ }
+
+ /// Creates a reference to an existing `struct cpumask` pointer.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime
+ /// of the returned reference.
+ pub unsafe fn from_raw<'a>(ptr: *const bindings::cpumask) -> &'a Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ unsafe { &*ptr.cast() }
+ }
+
+ /// Obtain the raw `struct cpumask *`.
+ pub fn as_raw(&self) -> *mut bindings::cpumask {
+ self as *const Cpumask as *mut bindings::cpumask
+ }
+
+ /// Sets `cpu` in the cpumask.
+ pub fn set(&mut self, cpu: u32) {
+ // SAFETY: `mask` is guaranteed to be valid for the lifetime of `self`. And it is safe to
+ // call `cpumask_set_cpus()` for any CPU.
+ unsafe { bindings::cpumask_set_cpu(cpu, self.as_raw()) };
+ }
+
+ /// Clears `cpu` in the cpumask.
+ pub fn clear(&mut self, cpu: i32) {
+ // SAFETY: `mask` is guaranteed to be valid for the lifetime of `self`. And it is safe to
+ // call `cpumask_clear_cpu()` for any CPU.
+ unsafe { bindings::cpumask_clear_cpu(cpu, self.as_raw()) };
+ }
+
+ /// Sets all CPUs in the cpumask.
+ pub fn set_all(&mut self) {
+ // SAFETY: `mask` is guaranteed to be valid for the lifetime of `self`. And it is safe to
+ // call `cpumask_setall()`.
+ unsafe { bindings::cpumask_setall(self.as_raw()) };
+ }
+
+ /// Gets weight of the cpumask.
+ pub fn weight(&self) -> u32 {
+ // SAFETY: `mask` is guaranteed to be valid for the lifetime of `self`. And it is safe to
+ // call `cpumask_weight()`.
+ unsafe { bindings::cpumask_weight(self.as_raw()) }
+ }
+
+ /// Copies cpumask.
+ pub fn copy(&self, dstp: &mut Self) {
+ // SAFETY: `mask` is guaranteed to be valid for the lifetime of `self`. And it is safe to
+ // call `cpumask_copy()`.
+ unsafe { bindings::cpumask_copy(dstp.as_raw(), self.as_raw()) };
+ }
+}
+
+/// This corresponds to the C type alias `cpumask_var_t`.
+pub struct CpumaskBox {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ ptr: NonNull<Cpumask>,
+ #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
+ mask: Cpumask,
+}
+
+impl CpumaskBox {
+ /// Creates an initialized instance of the `CpumaskBox`.
+ pub fn new(_flags: Flags) -> Result<Self, AllocError> {
+ Ok(Self {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ ptr: {
+ let mut ptr: *mut bindings::cpumask = ptr::null_mut();
+
+ // SAFETY: Depending on the value of `_flags`, this call may sleep. Other than
+ // that, it is always safe to call this method.
+ unsafe { bindings::zalloc_cpumask_var(&mut ptr, _flags.as_raw()) };
+ NonNull::new(ptr.cast()).ok_or(AllocError)?
+ },
+
+ #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
+ // SAFETY: FFI type is valid to be zero-initialized.
+ mask: unsafe { core::mem::zeroed() },
+ })
+ }
+
+ /// Creates an uninitialized instance of the `CpumaskBox`.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that the returned `CpumaskBox` is properly initialized before
+ /// getting used.
+ unsafe fn new_uninit(_flags: Flags) -> Result<Self, AllocError> {
+ Ok(Self {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ ptr: {
+ let mut ptr: *mut bindings::cpumask = ptr::null_mut();
+
+ // SAFETY: Depending on the value of `_flags`, this call may sleep. Other than
+ // that, it is always safe to call this method.
+ unsafe { bindings::alloc_cpumask_var(&mut ptr, _flags.as_raw()) };
+ NonNull::new(ptr.cast()).ok_or(AllocError)?
+ },
+ #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ mask: unsafe { MaybeUninit::uninit().assume_init() },
+ })
+ }
+
+ /// Creates a mutable reference to an existing `struct cpumask_var_t` pointer.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime
+ /// of the returned reference.
+ pub unsafe fn from_raw_mut<'a>(ptr: *mut bindings::cpumask_var_t) -> &'a mut Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ unsafe { &mut *ptr.cast() }
+ }
+
+ /// Creates a reference to an existing `struct cpumask_var_t` pointer.
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime
+ /// of the returned reference.
+ pub unsafe fn from_raw<'a>(ptr: *const bindings::cpumask_var_t) -> &'a Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ unsafe { &*ptr.cast() }
+ }
+
+ /// Clones cpumask.
+ pub fn try_clone(cpumask: &Cpumask) -> Result<Self> {
+ // SAFETY: The returned cpumask_box is initialized right after this call.
+ let mut cpumask_box = unsafe { Self::new_uninit(GFP_KERNEL) }?;
+
+ cpumask.copy(&mut cpumask_box);
+ Ok(cpumask_box)
+ }
+}
+
+// Make CpumaskBox behave like a pointer to Cpumask.
+impl Deref for CpumaskBox {
+ type Target = Cpumask;
+
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ fn deref(&self) -> &Cpumask {
+ // SAFETY: The caller owns CpumaskBox, so it is safe to deref the cpumask.
+ unsafe { &*self.ptr.as_ptr() }
+ }
+
+ #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
+ fn deref(&self) -> &Cpumask {
+ &self.mask
+ }
+}
+
+impl DerefMut for CpumaskBox {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ fn deref_mut(&mut self) -> &mut Cpumask {
+ // SAFETY: The caller owns CpumaskBox, so it is safe to deref the cpumask.
+ unsafe { self.ptr.as_mut() }
+ }
+
+ #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
+ fn deref_mut(&mut self) -> &mut Cpumask {
+ &mut self.mask
+ }
+}
+
+impl Drop for CpumaskBox {
+ fn drop(&mut self) {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ // SAFETY: It is safe to free the cpumask.
+ unsafe {
+ bindings::free_cpumask_var(self.as_raw())
+ };
+ }
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 496ed32b0911..efbd7be98dab 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -40,6 +40,7 @@
pub mod block;
#[doc(hidden)]
pub mod build_assert;
+pub mod cpumask;
pub mod cred;
pub mod device;
pub mod device_id;
--
2.31.1.272.g89b43f80a514
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