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@linaro.org>
---
rust/kernel/cpumask.rs | 330 +++++++++++++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 1 +
2 files changed, 331 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..c90bfac9346a
--- /dev/null
+++ b/rust/kernel/cpumask.rs
@@ -0,0 +1,330 @@
+// 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},
+ 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};
+
+/// A CPU Mask.
+///
+/// Rust abstraction for the C `struct cpumask`.
+///
+/// # Invariants
+///
+/// A [`Cpumask`] instance always corresponds to a valid C `struct cpumask`.
+///
+/// The callers must ensure that the `struct cpumask` is valid for access and
+/// remains valid for the lifetime of the returned reference.
+///
+/// ## Examples
+///
+/// The following example demonstrates how to update a [`Cpumask`].
+///
+/// ```
+/// use kernel::bindings;
+/// use kernel::cpumask::Cpumask;
+///
+/// fn set_clear_cpu(ptr: *mut bindings::cpumask, set_cpu: u32, clear_cpu: i32) {
+/// // SAFETY: The `ptr` is valid for writing and remains valid for the lifetime of the
+/// // returned reference.
+/// let mask = unsafe { Cpumask::as_mut_ref(ptr) };
+///
+/// mask.set(set_cpu);
+/// mask.clear(clear_cpu);
+/// }
+/// ```
+#[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 as_mut_ref<'a>(ptr: *mut bindings::cpumask) -> &'a mut Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ //
+ // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the
+ // lifetime of the returned reference.
+ 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 as_ref<'a>(ptr: *const bindings::cpumask) -> &'a Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ //
+ // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the
+ // lifetime of the returned reference.
+ unsafe { &*ptr.cast() }
+ }
+
+ /// Obtain the raw `struct cpumask` pointer.
+ pub fn as_raw(&self) -> *mut bindings::cpumask {
+ let this: *const Self = self;
+ this.cast_mut().cast()
+ }
+
+ /// Set `cpu` in the cpumask.
+ ///
+ /// ATTENTION: Contrary to C, this Rust `set()` method is non-atomic.
+ /// This mismatches kernel naming convention and corresponds to the C
+ /// function `__cpumask_set_cpu()`.
+ #[inline]
+ pub fn set(&mut self, cpu: u32) {
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `__cpumask_set_cpu`.
+ unsafe { bindings::__cpumask_set_cpu(cpu, self.as_raw()) };
+ }
+
+ /// Clear `cpu` in the cpumask.
+ ///
+ /// ATTENTION: Contrary to C, this Rust `clear()` method is non-atomic.
+ /// This mismatches kernel naming convention and corresponds to the C
+ /// function `__cpumask_clear_cpu()`.
+ #[inline]
+ pub fn clear(&mut self, cpu: i32) {
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to
+ // `__cpumask_clear_cpu`.
+ unsafe { bindings::__cpumask_clear_cpu(cpu, self.as_raw()) };
+ }
+
+ /// Test `cpu` in the cpumask.
+ ///
+ /// Equivalent to the kernel's `cpumask_test_cpu` API.
+ #[inline]
+ pub fn test(&self, cpu: i32) -> bool {
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_test_cpu`.
+ unsafe { bindings::cpumask_test_cpu(cpu, self.as_raw()) }
+ }
+
+ /// Set all CPUs in the cpumask.
+ ///
+ /// Equivalent to the kernel's `cpumask_setall` API.
+ #[inline]
+ pub fn setall(&mut self) {
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_setall`.
+ unsafe { bindings::cpumask_setall(self.as_raw()) };
+ }
+
+ /// Checks if cpumask is empty.
+ ///
+ /// Equivalent to the kernel's `cpumask_empty` API.
+ #[inline]
+ pub fn empty(&self) -> bool {
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_empty`.
+ unsafe { bindings::cpumask_empty(self.as_raw()) }
+ }
+
+ /// Checks if cpumask is full.
+ ///
+ /// Equivalent to the kernel's `cpumask_full` API.
+ #[inline]
+ pub fn full(&self) -> bool {
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_full`.
+ unsafe { bindings::cpumask_full(self.as_raw()) }
+ }
+
+ /// Get weight of the cpumask.
+ ///
+ /// Equivalent to the kernel's `cpumask_weight` API.
+ #[inline]
+ pub fn weight(&self) -> u32 {
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_weight`.
+ unsafe { bindings::cpumask_weight(self.as_raw()) }
+ }
+
+ /// Copy cpumask.
+ ///
+ /// Equivalent to the kernel's `cpumask_copy` API.
+ #[inline]
+ pub fn copy(&self, dstp: &mut Self) {
+ // SAFETY: By the type invariant, `Self::as_raw` is a valid argument to `cpumask_copy`.
+ unsafe { bindings::cpumask_copy(dstp.as_raw(), self.as_raw()) };
+ }
+}
+
+/// A CPU Mask pointer.
+///
+/// Rust abstraction for the C `struct cpumask_var_t`.
+///
+/// # Invariants
+///
+/// A [`CpumaskVar`] instance always corresponds to a valid C `struct cpumask_var_t`.
+///
+/// The callers must ensure that the `struct cpumask_var_t` is valid for access and remains valid
+/// for the lifetime of [`CpumaskVar`].
+///
+/// ## Examples
+///
+/// The following example demonstrates how to create and update a [`CpumaskVar`].
+///
+/// ```
+/// use kernel::cpumask::CpumaskVar;
+///
+/// let mut mask = CpumaskVar::new_zero(GFP_KERNEL).unwrap();
+///
+/// assert!(mask.empty());
+/// mask.set(2);
+/// assert!(mask.test(2));
+/// mask.set(3);
+/// assert!(mask.test(3));
+/// assert_eq!(mask.weight(), 2);
+///
+/// let mask2 = CpumaskVar::try_clone(&mask).unwrap();
+/// assert!(mask2.test(2));
+/// assert!(mask2.test(3));
+/// assert_eq!(mask2.weight(), 2);
+/// ```
+pub struct CpumaskVar {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ ptr: NonNull<Cpumask>,
+ #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
+ mask: Cpumask,
+}
+
+impl CpumaskVar {
+ /// Creates a zero-initialized instance of the [`CpumaskVar`].
+ pub fn new_zero(_flags: Flags) -> Result<Self, AllocError> {
+ Ok(Self {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ ptr: {
+ let mut ptr: *mut bindings::cpumask = ptr::null_mut();
+
+ // SAFETY: It is safe to call this method as the reference to `ptr` is valid.
+ //
+ // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of
+ // scope.
+ 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.
+ //
+ // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of scope.
+ mask: unsafe { core::mem::zeroed() },
+ })
+ }
+
+ /// Creates an instance of the [`CpumaskVar`].
+ ///
+ /// # Safety
+ ///
+ /// The caller must ensure that the returned [`CpumaskVar`] is properly initialized before
+ /// getting used.
+ pub unsafe fn new(_flags: Flags) -> Result<Self, AllocError> {
+ Ok(Self {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ ptr: {
+ let mut ptr: *mut bindings::cpumask = ptr::null_mut();
+
+ // SAFETY: It is safe to call this method as the reference to `ptr` is valid.
+ //
+ // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of
+ // scope.
+ 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.
+ //
+ // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of scope.
+ 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 as_mut_ref<'a>(ptr: *mut bindings::cpumask_var_t) -> &'a mut Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ //
+ // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the
+ // lifetime of the returned reference.
+ 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 as_ref<'a>(ptr: *const bindings::cpumask_var_t) -> &'a Self {
+ // SAFETY: Guaranteed by the safety requirements of the function.
+ //
+ // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the
+ // lifetime of the returned reference.
+ unsafe { &*ptr.cast() }
+ }
+
+ /// Clones cpumask.
+ pub fn try_clone(cpumask: &Cpumask) -> Result<Self> {
+ // SAFETY: The returned cpumask_var is initialized right after this call.
+ let mut cpumask_var = unsafe { Self::new(GFP_KERNEL) }?;
+
+ cpumask.copy(&mut cpumask_var);
+ Ok(cpumask_var)
+ }
+}
+
+// Make [`CpumaskVar`] behave like a pointer to [`Cpumask`].
+impl Deref for CpumaskVar {
+ type Target = Cpumask;
+
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ fn deref(&self) -> &Self::Target {
+ // SAFETY: The caller owns CpumaskVar, so it is safe to deref the cpumask.
+ unsafe { &*self.ptr.as_ptr() }
+ }
+
+ #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
+ fn deref(&self) -> &Self::Target {
+ &self.mask
+ }
+}
+
+impl DerefMut for CpumaskVar {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ fn deref_mut(&mut self) -> &mut Cpumask {
+ // SAFETY: The caller owns CpumaskVar, 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 CpumaskVar {
+ fn drop(&mut self) {
+ #[cfg(CONFIG_CPUMASK_OFFSTACK)]
+ // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `free_cpumask_var`.
+ unsafe {
+ bindings::free_cpumask_var(self.as_raw())
+ };
+ }
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index de07aadd1ff5..75f78f6bfaa6 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -42,6 +42,7 @@
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.g89b43f80a514On Mon, Apr 21, 2025 at 12:52:09PM +0530, Viresh Kumar wrote:
> 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@linaro.org>
Reviewed-by: Yury Norov [NVIDIA] <yury.norov@gmail.com>
> ---
> rust/kernel/cpumask.rs | 330 +++++++++++++++++++++++++++++++++++++++++
> rust/kernel/lib.rs | 1 +
> 2 files changed, 331 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..c90bfac9346a
> --- /dev/null
> +++ b/rust/kernel/cpumask.rs
> @@ -0,0 +1,330 @@
> +// 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},
> + 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};
> +
> +/// A CPU Mask.
> +///
> +/// Rust abstraction for the C `struct cpumask`.
> +///
> +/// # Invariants
> +///
> +/// A [`Cpumask`] instance always corresponds to a valid C `struct cpumask`.
> +///
> +/// The callers must ensure that the `struct cpumask` is valid for access and
> +/// remains valid for the lifetime of the returned reference.
> +///
> +/// ## Examples
> +///
> +/// The following example demonstrates how to update a [`Cpumask`].
> +///
> +/// ```
> +/// use kernel::bindings;
> +/// use kernel::cpumask::Cpumask;
> +///
> +/// fn set_clear_cpu(ptr: *mut bindings::cpumask, set_cpu: u32, clear_cpu: i32) {
> +/// // SAFETY: The `ptr` is valid for writing and remains valid for the lifetime of the
> +/// // returned reference.
> +/// let mask = unsafe { Cpumask::as_mut_ref(ptr) };
> +///
> +/// mask.set(set_cpu);
> +/// mask.clear(clear_cpu);
> +/// }
> +/// ```
> +#[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 as_mut_ref<'a>(ptr: *mut bindings::cpumask) -> &'a mut Self {
> + // SAFETY: Guaranteed by the safety requirements of the function.
> + //
> + // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the
> + // lifetime of the returned reference.
> + 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 as_ref<'a>(ptr: *const bindings::cpumask) -> &'a Self {
> + // SAFETY: Guaranteed by the safety requirements of the function.
> + //
> + // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the
> + // lifetime of the returned reference.
> + unsafe { &*ptr.cast() }
> + }
> +
> + /// Obtain the raw `struct cpumask` pointer.
> + pub fn as_raw(&self) -> *mut bindings::cpumask {
> + let this: *const Self = self;
> + this.cast_mut().cast()
> + }
> +
> + /// Set `cpu` in the cpumask.
> + ///
> + /// ATTENTION: Contrary to C, this Rust `set()` method is non-atomic.
> + /// This mismatches kernel naming convention and corresponds to the C
> + /// function `__cpumask_set_cpu()`.
> + #[inline]
> + pub fn set(&mut self, cpu: u32) {
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `__cpumask_set_cpu`.
> + unsafe { bindings::__cpumask_set_cpu(cpu, self.as_raw()) };
> + }
> +
> + /// Clear `cpu` in the cpumask.
> + ///
> + /// ATTENTION: Contrary to C, this Rust `clear()` method is non-atomic.
> + /// This mismatches kernel naming convention and corresponds to the C
> + /// function `__cpumask_clear_cpu()`.
> + #[inline]
> + pub fn clear(&mut self, cpu: i32) {
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to
> + // `__cpumask_clear_cpu`.
> + unsafe { bindings::__cpumask_clear_cpu(cpu, self.as_raw()) };
> + }
> +
> + /// Test `cpu` in the cpumask.
> + ///
> + /// Equivalent to the kernel's `cpumask_test_cpu` API.
> + #[inline]
> + pub fn test(&self, cpu: i32) -> bool {
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_test_cpu`.
> + unsafe { bindings::cpumask_test_cpu(cpu, self.as_raw()) }
> + }
> +
> + /// Set all CPUs in the cpumask.
> + ///
> + /// Equivalent to the kernel's `cpumask_setall` API.
> + #[inline]
> + pub fn setall(&mut self) {
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_setall`.
> + unsafe { bindings::cpumask_setall(self.as_raw()) };
> + }
> +
> + /// Checks if cpumask is empty.
> + ///
> + /// Equivalent to the kernel's `cpumask_empty` API.
> + #[inline]
> + pub fn empty(&self) -> bool {
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_empty`.
> + unsafe { bindings::cpumask_empty(self.as_raw()) }
> + }
> +
> + /// Checks if cpumask is full.
> + ///
> + /// Equivalent to the kernel's `cpumask_full` API.
> + #[inline]
> + pub fn full(&self) -> bool {
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_full`.
> + unsafe { bindings::cpumask_full(self.as_raw()) }
> + }
> +
> + /// Get weight of the cpumask.
> + ///
> + /// Equivalent to the kernel's `cpumask_weight` API.
> + #[inline]
> + pub fn weight(&self) -> u32 {
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_weight`.
> + unsafe { bindings::cpumask_weight(self.as_raw()) }
> + }
> +
> + /// Copy cpumask.
> + ///
> + /// Equivalent to the kernel's `cpumask_copy` API.
> + #[inline]
> + pub fn copy(&self, dstp: &mut Self) {
> + // SAFETY: By the type invariant, `Self::as_raw` is a valid argument to `cpumask_copy`.
> + unsafe { bindings::cpumask_copy(dstp.as_raw(), self.as_raw()) };
> + }
> +}
> +
> +/// A CPU Mask pointer.
> +///
> +/// Rust abstraction for the C `struct cpumask_var_t`.
> +///
> +/// # Invariants
> +///
> +/// A [`CpumaskVar`] instance always corresponds to a valid C `struct cpumask_var_t`.
> +///
> +/// The callers must ensure that the `struct cpumask_var_t` is valid for access and remains valid
> +/// for the lifetime of [`CpumaskVar`].
> +///
> +/// ## Examples
> +///
> +/// The following example demonstrates how to create and update a [`CpumaskVar`].
> +///
> +/// ```
> +/// use kernel::cpumask::CpumaskVar;
> +///
> +/// let mut mask = CpumaskVar::new_zero(GFP_KERNEL).unwrap();
> +///
> +/// assert!(mask.empty());
> +/// mask.set(2);
> +/// assert!(mask.test(2));
> +/// mask.set(3);
> +/// assert!(mask.test(3));
> +/// assert_eq!(mask.weight(), 2);
> +///
> +/// let mask2 = CpumaskVar::try_clone(&mask).unwrap();
> +/// assert!(mask2.test(2));
> +/// assert!(mask2.test(3));
> +/// assert_eq!(mask2.weight(), 2);
> +/// ```
> +pub struct CpumaskVar {
> + #[cfg(CONFIG_CPUMASK_OFFSTACK)]
> + ptr: NonNull<Cpumask>,
> + #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
> + mask: Cpumask,
> +}
> +
> +impl CpumaskVar {
> + /// Creates a zero-initialized instance of the [`CpumaskVar`].
> + pub fn new_zero(_flags: Flags) -> Result<Self, AllocError> {
> + Ok(Self {
> + #[cfg(CONFIG_CPUMASK_OFFSTACK)]
> + ptr: {
> + let mut ptr: *mut bindings::cpumask = ptr::null_mut();
> +
> + // SAFETY: It is safe to call this method as the reference to `ptr` is valid.
> + //
> + // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of
> + // scope.
> + 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.
> + //
> + // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of scope.
> + mask: unsafe { core::mem::zeroed() },
> + })
> + }
> +
> + /// Creates an instance of the [`CpumaskVar`].
> + ///
> + /// # Safety
> + ///
> + /// The caller must ensure that the returned [`CpumaskVar`] is properly initialized before
> + /// getting used.
> + pub unsafe fn new(_flags: Flags) -> Result<Self, AllocError> {
> + Ok(Self {
> + #[cfg(CONFIG_CPUMASK_OFFSTACK)]
> + ptr: {
> + let mut ptr: *mut bindings::cpumask = ptr::null_mut();
> +
> + // SAFETY: It is safe to call this method as the reference to `ptr` is valid.
> + //
> + // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of
> + // scope.
> + 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.
> + //
> + // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of scope.
> + 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 as_mut_ref<'a>(ptr: *mut bindings::cpumask_var_t) -> &'a mut Self {
> + // SAFETY: Guaranteed by the safety requirements of the function.
> + //
> + // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the
> + // lifetime of the returned reference.
> + 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 as_ref<'a>(ptr: *const bindings::cpumask_var_t) -> &'a Self {
> + // SAFETY: Guaranteed by the safety requirements of the function.
> + //
> + // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the
> + // lifetime of the returned reference.
> + unsafe { &*ptr.cast() }
> + }
> +
> + /// Clones cpumask.
> + pub fn try_clone(cpumask: &Cpumask) -> Result<Self> {
> + // SAFETY: The returned cpumask_var is initialized right after this call.
> + let mut cpumask_var = unsafe { Self::new(GFP_KERNEL) }?;
> +
> + cpumask.copy(&mut cpumask_var);
> + Ok(cpumask_var)
> + }
> +}
> +
> +// Make [`CpumaskVar`] behave like a pointer to [`Cpumask`].
> +impl Deref for CpumaskVar {
> + type Target = Cpumask;
> +
> + #[cfg(CONFIG_CPUMASK_OFFSTACK)]
> + fn deref(&self) -> &Self::Target {
> + // SAFETY: The caller owns CpumaskVar, so it is safe to deref the cpumask.
> + unsafe { &*self.ptr.as_ptr() }
> + }
> +
> + #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
> + fn deref(&self) -> &Self::Target {
> + &self.mask
> + }
> +}
> +
> +impl DerefMut for CpumaskVar {
> + #[cfg(CONFIG_CPUMASK_OFFSTACK)]
> + fn deref_mut(&mut self) -> &mut Cpumask {
> + // SAFETY: The caller owns CpumaskVar, 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 CpumaskVar {
> + fn drop(&mut self) {
> + #[cfg(CONFIG_CPUMASK_OFFSTACK)]
> + // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `free_cpumask_var`.
> + unsafe {
> + bindings::free_cpumask_var(self.as_raw())
> + };
> + }
> +}
> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> index de07aadd1ff5..75f78f6bfaa6 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -42,6 +42,7 @@
> 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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