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1// SPDX-License-Identifier: GPL-2.0
2
3//! CPU Mask abstractions.
4//!
5//! C header: [`include/linux/cpumask.h`](srctree/include/linux/cpumask.h)
6
7use crate::{
8 alloc::{AllocError, Flags},
9 cpu::CpuId,
10 prelude::*,
11 types::Opaque,
12};
13
14#[cfg(CONFIG_CPUMASK_OFFSTACK)]
15use core::ptr::{self, NonNull};
16
17use core::ops::{Deref, DerefMut};
18
19/// A CPU Mask.
20///
21/// Rust abstraction for the C `struct cpumask`.
22///
23/// # Invariants
24///
25/// A [`Cpumask`] instance always corresponds to a valid C `struct cpumask`.
26///
27/// The callers must ensure that the `struct cpumask` is valid for access and
28/// remains valid for the lifetime of the returned reference.
29///
30/// # Examples
31///
32/// The following example demonstrates how to update a [`Cpumask`].
33///
34/// ```
35/// use kernel::bindings;
36/// use kernel::cpu::CpuId;
37/// use kernel::cpumask::Cpumask;
38///
39/// fn set_clear_cpu(ptr: *mut bindings::cpumask, set_cpu: CpuId, clear_cpu: CpuId) {
40/// // SAFETY: The `ptr` is valid for writing and remains valid for the lifetime of the
41/// // returned reference.
42/// let mask = unsafe { Cpumask::from_raw_mut(ptr) };
43///
44/// mask.set(set_cpu);
45/// mask.clear(clear_cpu);
46/// }
47/// ```
48#[repr(transparent)]
49pub struct Cpumask(Opaque<bindings::cpumask>);
50
51impl Cpumask {
52 /// Creates a mutable reference from an existing `struct cpumask` pointer.
53 ///
54 /// # Safety
55 ///
56 /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime
57 /// of the returned reference.
58 pub unsafe fn from_raw_mut<'a>(ptr: *mut bindings::cpumask) -> &'a mut Self {
59 // SAFETY: Guaranteed by the safety requirements of the function.
60 //
61 // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the
62 // lifetime of the returned reference.
63 unsafe { &mut *ptr.cast() }
64 }
65
66 /// Creates a reference from an existing `struct cpumask` pointer.
67 ///
68 /// # Safety
69 ///
70 /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime
71 /// of the returned reference.
72 pub unsafe fn from_raw<'a>(ptr: *const bindings::cpumask) -> &'a Self {
73 // SAFETY: Guaranteed by the safety requirements of the function.
74 //
75 // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the
76 // lifetime of the returned reference.
77 unsafe { &*ptr.cast() }
78 }
79
80 /// Obtain the raw `struct cpumask` pointer.
81 pub fn as_raw(&self) -> *mut bindings::cpumask {
82 let this: *const Self = self;
83 this.cast_mut().cast()
84 }
85
86 /// Set `cpu` in the cpumask.
87 ///
88 /// ATTENTION: Contrary to C, this Rust `set()` method is non-atomic.
89 /// This mismatches kernel naming convention and corresponds to the C
90 /// function `__cpumask_set_cpu()`.
91 #[inline]
92 pub fn set(&mut self, cpu: CpuId) {
93 // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `__cpumask_set_cpu`.
94 unsafe { bindings::__cpumask_set_cpu(u32::from(cpu), self.as_raw()) };
95 }
96
97 /// Clear `cpu` in the cpumask.
98 ///
99 /// ATTENTION: Contrary to C, this Rust `clear()` method is non-atomic.
100 /// This mismatches kernel naming convention and corresponds to the C
101 /// function `__cpumask_clear_cpu()`.
102 #[inline]
103 pub fn clear(&mut self, cpu: CpuId) {
104 // SAFETY: By the type invariant, `self.as_raw` is a valid argument to
105 // `__cpumask_clear_cpu`.
106 unsafe { bindings::__cpumask_clear_cpu(i32::from(cpu), self.as_raw()) };
107 }
108
109 /// Test `cpu` in the cpumask.
110 ///
111 /// Equivalent to the kernel's `cpumask_test_cpu` API.
112 #[inline]
113 pub fn test(&self, cpu: CpuId) -> bool {
114 // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_test_cpu`.
115 unsafe { bindings::cpumask_test_cpu(i32::from(cpu), self.as_raw()) }
116 }
117
118 /// Set all CPUs in the cpumask.
119 ///
120 /// Equivalent to the kernel's `cpumask_setall` API.
121 #[inline]
122 pub fn setall(&mut self) {
123 // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_setall`.
124 unsafe { bindings::cpumask_setall(self.as_raw()) };
125 }
126
127 /// Checks if cpumask is empty.
128 ///
129 /// Equivalent to the kernel's `cpumask_empty` API.
130 #[inline]
131 pub fn empty(&self) -> bool {
132 // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_empty`.
133 unsafe { bindings::cpumask_empty(self.as_raw()) }
134 }
135
136 /// Checks if cpumask is full.
137 ///
138 /// Equivalent to the kernel's `cpumask_full` API.
139 #[inline]
140 pub fn full(&self) -> bool {
141 // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_full`.
142 unsafe { bindings::cpumask_full(self.as_raw()) }
143 }
144
145 /// Get weight of the cpumask.
146 ///
147 /// Equivalent to the kernel's `cpumask_weight` API.
148 #[inline]
149 pub fn weight(&self) -> u32 {
150 // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `cpumask_weight`.
151 unsafe { bindings::cpumask_weight(self.as_raw()) }
152 }
153
154 /// Copy cpumask.
155 ///
156 /// Equivalent to the kernel's `cpumask_copy` API.
157 #[inline]
158 pub fn copy(&self, dstp: &mut Self) {
159 // SAFETY: By the type invariant, `Self::as_raw` is a valid argument to `cpumask_copy`.
160 unsafe { bindings::cpumask_copy(dstp.as_raw(), self.as_raw()) };
161 }
162}
163
164/// A CPU Mask pointer.
165///
166/// Rust abstraction for the C `struct cpumask_var_t`.
167///
168/// # Invariants
169///
170/// A [`CpumaskVar`] instance always corresponds to a valid C `struct cpumask_var_t`.
171///
172/// The callers must ensure that the `struct cpumask_var_t` is valid for access and remains valid
173/// for the lifetime of [`CpumaskVar`].
174///
175/// # Examples
176///
177/// The following example demonstrates how to create and update a [`CpumaskVar`].
178///
179/// ```
180/// use kernel::cpu::CpuId;
181/// use kernel::cpumask::CpumaskVar;
182///
183/// let mut mask = CpumaskVar::new_zero(GFP_KERNEL).unwrap();
184///
185/// assert!(mask.empty());
186/// let mut count = 0;
187///
188/// let cpu2 = CpuId::from_u32(2);
189/// if let Some(cpu) = cpu2 {
190/// mask.set(cpu);
191/// assert!(mask.test(cpu));
192/// count += 1;
193/// }
194///
195/// let cpu3 = CpuId::from_u32(3);
196/// if let Some(cpu) = cpu3 {
197/// mask.set(cpu);
198/// assert!(mask.test(cpu));
199/// count += 1;
200/// }
201///
202/// assert_eq!(mask.weight(), count);
203///
204/// let mask2 = CpumaskVar::try_clone(&mask).unwrap();
205///
206/// if let Some(cpu) = cpu2 {
207/// assert!(mask2.test(cpu));
208/// }
209///
210/// if let Some(cpu) = cpu3 {
211/// assert!(mask2.test(cpu));
212/// }
213/// assert_eq!(mask2.weight(), count);
214/// ```
215#[repr(transparent)]
216pub struct CpumaskVar {
217 #[cfg(CONFIG_CPUMASK_OFFSTACK)]
218 ptr: NonNull<Cpumask>,
219 #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
220 mask: Cpumask,
221}
222
223impl CpumaskVar {
224 /// Creates a zero-initialized instance of the [`CpumaskVar`].
225 pub fn new_zero(_flags: Flags) -> Result<Self, AllocError> {
226 Ok(Self {
227 #[cfg(CONFIG_CPUMASK_OFFSTACK)]
228 ptr: {
229 let mut ptr: *mut bindings::cpumask = ptr::null_mut();
230
231 // SAFETY: It is safe to call this method as the reference to `ptr` is valid.
232 //
233 // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of
234 // scope.
235 unsafe { bindings::zalloc_cpumask_var(&mut ptr, _flags.as_raw()) };
236 NonNull::new(ptr.cast()).ok_or(AllocError)?
237 },
238
239 #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
240 mask: Cpumask(Opaque::zeroed()),
241 })
242 }
243
244 /// Creates an instance of the [`CpumaskVar`].
245 ///
246 /// # Safety
247 ///
248 /// The caller must ensure that the returned [`CpumaskVar`] is properly initialized before
249 /// getting used.
250 pub unsafe fn new(_flags: Flags) -> Result<Self, AllocError> {
251 Ok(Self {
252 #[cfg(CONFIG_CPUMASK_OFFSTACK)]
253 ptr: {
254 let mut ptr: *mut bindings::cpumask = ptr::null_mut();
255
256 // SAFETY: It is safe to call this method as the reference to `ptr` is valid.
257 //
258 // INVARIANT: The associated memory is freed when the `CpumaskVar` goes out of
259 // scope.
260 unsafe { bindings::alloc_cpumask_var(&mut ptr, _flags.as_raw()) };
261 NonNull::new(ptr.cast()).ok_or(AllocError)?
262 },
263 #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
264 mask: Cpumask(Opaque::uninit()),
265 })
266 }
267
268 /// Creates a mutable reference to an existing `struct cpumask_var_t` pointer.
269 ///
270 /// # Safety
271 ///
272 /// The caller must ensure that `ptr` is valid for writing and remains valid for the lifetime
273 /// of the returned reference.
274 pub unsafe fn from_raw_mut<'a>(ptr: *mut bindings::cpumask_var_t) -> &'a mut Self {
275 // SAFETY: Guaranteed by the safety requirements of the function.
276 //
277 // INVARIANT: The caller ensures that `ptr` is valid for writing and remains valid for the
278 // lifetime of the returned reference.
279 unsafe { &mut *ptr.cast() }
280 }
281
282 /// Creates a reference to an existing `struct cpumask_var_t` pointer.
283 ///
284 /// # Safety
285 ///
286 /// The caller must ensure that `ptr` is valid for reading and remains valid for the lifetime
287 /// of the returned reference.
288 pub unsafe fn from_raw<'a>(ptr: *const bindings::cpumask_var_t) -> &'a Self {
289 // SAFETY: Guaranteed by the safety requirements of the function.
290 //
291 // INVARIANT: The caller ensures that `ptr` is valid for reading and remains valid for the
292 // lifetime of the returned reference.
293 unsafe { &*ptr.cast() }
294 }
295
296 /// Clones cpumask.
297 pub fn try_clone(cpumask: &Cpumask) -> Result<Self> {
298 // SAFETY: The returned cpumask_var is initialized right after this call.
299 let mut cpumask_var = unsafe { Self::new(GFP_KERNEL) }?;
300
301 cpumask.copy(&mut cpumask_var);
302 Ok(cpumask_var)
303 }
304}
305
306// Make [`CpumaskVar`] behave like a pointer to [`Cpumask`].
307impl Deref for CpumaskVar {
308 type Target = Cpumask;
309
310 #[cfg(CONFIG_CPUMASK_OFFSTACK)]
311 fn deref(&self) -> &Self::Target {
312 // SAFETY: The caller owns CpumaskVar, so it is safe to deref the cpumask.
313 unsafe { &*self.ptr.as_ptr() }
314 }
315
316 #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
317 fn deref(&self) -> &Self::Target {
318 &self.mask
319 }
320}
321
322impl DerefMut for CpumaskVar {
323 #[cfg(CONFIG_CPUMASK_OFFSTACK)]
324 fn deref_mut(&mut self) -> &mut Cpumask {
325 // SAFETY: The caller owns CpumaskVar, so it is safe to deref the cpumask.
326 unsafe { self.ptr.as_mut() }
327 }
328
329 #[cfg(not(CONFIG_CPUMASK_OFFSTACK))]
330 fn deref_mut(&mut self) -> &mut Cpumask {
331 &mut self.mask
332 }
333}
334
335impl Drop for CpumaskVar {
336 fn drop(&mut self) {
337 #[cfg(CONFIG_CPUMASK_OFFSTACK)]
338 // SAFETY: By the type invariant, `self.as_raw` is a valid argument to `free_cpumask_var`.
339 unsafe {
340 bindings::free_cpumask_var(self.as_raw())
341 };
342 }
343}