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1// SPDX-License-Identifier: GPL-2.0
2
3//! Work queues.
4//!
5//! This file has two components: The raw work item API, and the safe work item API.
6//!
7//! One pattern that is used in both APIs is the `ID` const generic, which exists to allow a single
8//! type to define multiple `work_struct` fields. This is done by choosing an id for each field,
9//! and using that id to specify which field you wish to use. (The actual value doesn't matter, as
10//! long as you use different values for different fields of the same struct.) Since these IDs are
11//! generic, they are used only at compile-time, so they shouldn't exist in the final binary.
12//!
13//! # The raw API
14//!
15//! The raw API consists of the [`RawWorkItem`] trait, where the work item needs to provide an
16//! arbitrary function that knows how to enqueue the work item. It should usually not be used
17//! directly, but if you want to, you can use it without using the pieces from the safe API.
18//!
19//! # The safe API
20//!
21//! The safe API is used via the [`Work`] struct and [`WorkItem`] traits. Furthermore, it also
22//! includes a trait called [`WorkItemPointer`], which is usually not used directly by the user.
23//!
24//! * The [`Work`] struct is the Rust wrapper for the C `work_struct` type.
25//! * The [`WorkItem`] trait is implemented for structs that can be enqueued to a workqueue.
26//! * The [`WorkItemPointer`] trait is implemented for the pointer type that points at a something
27//! that implements [`WorkItem`].
28//!
29//! ## Example
30//!
31//! This example defines a struct that holds an integer and can be scheduled on the workqueue. When
32//! the struct is executed, it will print the integer. Since there is only one `work_struct` field,
33//! we do not need to specify ids for the fields.
34//!
35//! ```
36//! use kernel::sync::Arc;
37//! use kernel::workqueue::{self, impl_has_work, new_work, Work, WorkItem};
38//!
39//! #[pin_data]
40//! struct MyStruct {
41//! value: i32,
42//! #[pin]
43//! work: Work<MyStruct>,
44//! }
45//!
46//! impl_has_work! {
47//! impl HasWork<Self> for MyStruct { self.work }
48//! }
49//!
50//! impl MyStruct {
51//! fn new(value: i32) -> Result<Arc<Self>> {
52//! Arc::pin_init(pin_init!(MyStruct {
53//! value,
54//! work <- new_work!("MyStruct::work"),
55//! }), GFP_KERNEL)
56//! }
57//! }
58//!
59//! impl WorkItem for MyStruct {
60//! type Pointer = Arc<MyStruct>;
61//!
62//! fn run(this: Arc<MyStruct>) {
63//! pr_info!("The value is: {}", this.value);
64//! }
65//! }
66//!
67//! /// This method will enqueue the struct for execution on the system workqueue, where its value
68//! /// will be printed.
69//! fn print_later(val: Arc<MyStruct>) {
70//! let _ = workqueue::system().enqueue(val);
71//! }
72//! ```
73//!
74//! The following example shows how multiple `work_struct` fields can be used:
75//!
76//! ```
77//! use kernel::sync::Arc;
78//! use kernel::workqueue::{self, impl_has_work, new_work, Work, WorkItem};
79//!
80//! #[pin_data]
81//! struct MyStruct {
82//! value_1: i32,
83//! value_2: i32,
84//! #[pin]
85//! work_1: Work<MyStruct, 1>,
86//! #[pin]
87//! work_2: Work<MyStruct, 2>,
88//! }
89//!
90//! impl_has_work! {
91//! impl HasWork<Self, 1> for MyStruct { self.work_1 }
92//! impl HasWork<Self, 2> for MyStruct { self.work_2 }
93//! }
94//!
95//! impl MyStruct {
96//! fn new(value_1: i32, value_2: i32) -> Result<Arc<Self>> {
97//! Arc::pin_init(pin_init!(MyStruct {
98//! value_1,
99//! value_2,
100//! work_1 <- new_work!("MyStruct::work_1"),
101//! work_2 <- new_work!("MyStruct::work_2"),
102//! }), GFP_KERNEL)
103//! }
104//! }
105//!
106//! impl WorkItem<1> for MyStruct {
107//! type Pointer = Arc<MyStruct>;
108//!
109//! fn run(this: Arc<MyStruct>) {
110//! pr_info!("The value is: {}", this.value_1);
111//! }
112//! }
113//!
114//! impl WorkItem<2> for MyStruct {
115//! type Pointer = Arc<MyStruct>;
116//!
117//! fn run(this: Arc<MyStruct>) {
118//! pr_info!("The second value is: {}", this.value_2);
119//! }
120//! }
121//!
122//! fn print_1_later(val: Arc<MyStruct>) {
123//! let _ = workqueue::system().enqueue::<Arc<MyStruct>, 1>(val);
124//! }
125//!
126//! fn print_2_later(val: Arc<MyStruct>) {
127//! let _ = workqueue::system().enqueue::<Arc<MyStruct>, 2>(val);
128//! }
129//! ```
130//!
131//! C header: [`include/linux/workqueue.h`](srctree/include/linux/workqueue.h)
132
133use crate::alloc::{AllocError, Flags};
134use crate::{prelude::*, sync::Arc, sync::LockClassKey, types::Opaque};
135use core::marker::PhantomData;
136
137/// Creates a [`Work`] initialiser with the given name and a newly-created lock class.
138#[macro_export]
139macro_rules! new_work {
140 ($($name:literal)?) => {
141 $crate::workqueue::Work::new($crate::optional_name!($($name)?), $crate::static_lock_class!())
142 };
143}
144pub use new_work;
145
146/// A kernel work queue.
147///
148/// Wraps the kernel's C `struct workqueue_struct`.
149///
150/// It allows work items to be queued to run on thread pools managed by the kernel. Several are
151/// always available, for example, `system`, `system_highpri`, `system_long`, etc.
152#[repr(transparent)]
153pub struct Queue(Opaque<bindings::workqueue_struct>);
154
155// SAFETY: Accesses to workqueues used by [`Queue`] are thread-safe.
156unsafe impl Send for Queue {}
157// SAFETY: Accesses to workqueues used by [`Queue`] are thread-safe.
158unsafe impl Sync for Queue {}
159
160impl Queue {
161 /// Use the provided `struct workqueue_struct` with Rust.
162 ///
163 /// # Safety
164 ///
165 /// The caller must ensure that the provided raw pointer is not dangling, that it points at a
166 /// valid workqueue, and that it remains valid until the end of `'a`.
167 pub unsafe fn from_raw<'a>(ptr: *const bindings::workqueue_struct) -> &'a Queue {
168 // SAFETY: The `Queue` type is `#[repr(transparent)]`, so the pointer cast is valid. The
169 // caller promises that the pointer is not dangling.
170 unsafe { &*(ptr as *const Queue) }
171 }
172
173 /// Enqueues a work item.
174 ///
175 /// This may fail if the work item is already enqueued in a workqueue.
176 ///
177 /// The work item will be submitted using `WORK_CPU_UNBOUND`.
178 pub fn enqueue<W, const ID: u64>(&self, w: W) -> W::EnqueueOutput
179 where
180 W: RawWorkItem<ID> + Send + 'static,
181 {
182 let queue_ptr = self.0.get();
183
184 // SAFETY: We only return `false` if the `work_struct` is already in a workqueue. The other
185 // `__enqueue` requirements are not relevant since `W` is `Send` and static.
186 //
187 // The call to `bindings::queue_work_on` will dereference the provided raw pointer, which
188 // is ok because `__enqueue` guarantees that the pointer is valid for the duration of this
189 // closure.
190 //
191 // Furthermore, if the C workqueue code accesses the pointer after this call to
192 // `__enqueue`, then the work item was successfully enqueued, and `bindings::queue_work_on`
193 // will have returned true. In this case, `__enqueue` promises that the raw pointer will
194 // stay valid until we call the function pointer in the `work_struct`, so the access is ok.
195 unsafe {
196 w.__enqueue(move |work_ptr| {
197 bindings::queue_work_on(
198 bindings::wq_misc_consts_WORK_CPU_UNBOUND as _,
199 queue_ptr,
200 work_ptr,
201 )
202 })
203 }
204 }
205
206 /// Tries to spawn the given function or closure as a work item.
207 ///
208 /// This method can fail because it allocates memory to store the work item.
209 pub fn try_spawn<T: 'static + Send + FnOnce()>(
210 &self,
211 flags: Flags,
212 func: T,
213 ) -> Result<(), AllocError> {
214 let init = pin_init!(ClosureWork {
215 work <- new_work!("Queue::try_spawn"),
216 func: Some(func),
217 });
218
219 self.enqueue(Box::pin_init(init, flags).map_err(|_| AllocError)?);
220 Ok(())
221 }
222}
223
224/// A helper type used in [`try_spawn`].
225///
226/// [`try_spawn`]: Queue::try_spawn
227#[pin_data]
228struct ClosureWork<T> {
229 #[pin]
230 work: Work<ClosureWork<T>>,
231 func: Option<T>,
232}
233
234impl<T> ClosureWork<T> {
235 fn project(self: Pin<&mut Self>) -> &mut Option<T> {
236 // SAFETY: The `func` field is not structurally pinned.
237 unsafe { &mut self.get_unchecked_mut().func }
238 }
239}
240
241impl<T: FnOnce()> WorkItem for ClosureWork<T> {
242 type Pointer = Pin<Box<Self>>;
243
244 fn run(mut this: Pin<Box<Self>>) {
245 if let Some(func) = this.as_mut().project().take() {
246 (func)()
247 }
248 }
249}
250
251/// A raw work item.
252///
253/// This is the low-level trait that is designed for being as general as possible.
254///
255/// The `ID` parameter to this trait exists so that a single type can provide multiple
256/// implementations of this trait. For example, if a struct has multiple `work_struct` fields, then
257/// you will implement this trait once for each field, using a different id for each field. The
258/// actual value of the id is not important as long as you use different ids for different fields
259/// of the same struct. (Fields of different structs need not use different ids.)
260///
261/// Note that the id is used only to select the right method to call during compilation. It won't be
262/// part of the final executable.
263///
264/// # Safety
265///
266/// Implementers must ensure that any pointers passed to a `queue_work_on` closure by [`__enqueue`]
267/// remain valid for the duration specified in the guarantees section of the documentation for
268/// [`__enqueue`].
269///
270/// [`__enqueue`]: RawWorkItem::__enqueue
271pub unsafe trait RawWorkItem<const ID: u64> {
272 /// The return type of [`Queue::enqueue`].
273 type EnqueueOutput;
274
275 /// Enqueues this work item on a queue using the provided `queue_work_on` method.
276 ///
277 /// # Guarantees
278 ///
279 /// If this method calls the provided closure, then the raw pointer is guaranteed to point at a
280 /// valid `work_struct` for the duration of the call to the closure. If the closure returns
281 /// true, then it is further guaranteed that the pointer remains valid until someone calls the
282 /// function pointer stored in the `work_struct`.
283 ///
284 /// # Safety
285 ///
286 /// The provided closure may only return `false` if the `work_struct` is already in a workqueue.
287 ///
288 /// If the work item type is annotated with any lifetimes, then you must not call the function
289 /// pointer after any such lifetime expires. (Never calling the function pointer is okay.)
290 ///
291 /// If the work item type is not [`Send`], then the function pointer must be called on the same
292 /// thread as the call to `__enqueue`.
293 unsafe fn __enqueue<F>(self, queue_work_on: F) -> Self::EnqueueOutput
294 where
295 F: FnOnce(*mut bindings::work_struct) -> bool;
296}
297
298/// Defines the method that should be called directly when a work item is executed.
299///
300/// This trait is implemented by `Pin<Box<T>>` and [`Arc<T>`], and is mainly intended to be
301/// implemented for smart pointer types. For your own structs, you would implement [`WorkItem`]
302/// instead. The [`run`] method on this trait will usually just perform the appropriate
303/// `container_of` translation and then call into the [`run`][WorkItem::run] method from the
304/// [`WorkItem`] trait.
305///
306/// This trait is used when the `work_struct` field is defined using the [`Work`] helper.
307///
308/// # Safety
309///
310/// Implementers must ensure that [`__enqueue`] uses a `work_struct` initialized with the [`run`]
311/// method of this trait as the function pointer.
312///
313/// [`__enqueue`]: RawWorkItem::__enqueue
314/// [`run`]: WorkItemPointer::run
315pub unsafe trait WorkItemPointer<const ID: u64>: RawWorkItem<ID> {
316 /// Run this work item.
317 ///
318 /// # Safety
319 ///
320 /// The provided `work_struct` pointer must originate from a previous call to [`__enqueue`]
321 /// where the `queue_work_on` closure returned true, and the pointer must still be valid.
322 ///
323 /// [`__enqueue`]: RawWorkItem::__enqueue
324 unsafe extern "C" fn run(ptr: *mut bindings::work_struct);
325}
326
327/// Defines the method that should be called when this work item is executed.
328///
329/// This trait is used when the `work_struct` field is defined using the [`Work`] helper.
330pub trait WorkItem<const ID: u64 = 0> {
331 /// The pointer type that this struct is wrapped in. This will typically be `Arc<Self>` or
332 /// `Pin<Box<Self>>`.
333 type Pointer: WorkItemPointer<ID>;
334
335 /// The method that should be called when this work item is executed.
336 fn run(this: Self::Pointer);
337}
338
339/// Links for a work item.
340///
341/// This struct contains a function pointer to the [`run`] function from the [`WorkItemPointer`]
342/// trait, and defines the linked list pointers necessary to enqueue a work item in a workqueue.
343///
344/// Wraps the kernel's C `struct work_struct`.
345///
346/// This is a helper type used to associate a `work_struct` with the [`WorkItem`] that uses it.
347///
348/// [`run`]: WorkItemPointer::run
349#[pin_data]
350#[repr(transparent)]
351pub struct Work<T: ?Sized, const ID: u64 = 0> {
352 #[pin]
353 work: Opaque<bindings::work_struct>,
354 _inner: PhantomData<T>,
355}
356
357// SAFETY: Kernel work items are usable from any thread.
358//
359// We do not need to constrain `T` since the work item does not actually contain a `T`.
360unsafe impl<T: ?Sized, const ID: u64> Send for Work<T, ID> {}
361// SAFETY: Kernel work items are usable from any thread.
362//
363// We do not need to constrain `T` since the work item does not actually contain a `T`.
364unsafe impl<T: ?Sized, const ID: u64> Sync for Work<T, ID> {}
365
366impl<T: ?Sized, const ID: u64> Work<T, ID> {
367 /// Creates a new instance of [`Work`].
368 #[inline]
369 #[allow(clippy::new_ret_no_self)]
370 pub fn new(name: &'static CStr, key: &'static LockClassKey) -> impl PinInit<Self>
371 where
372 T: WorkItem<ID>,
373 {
374 pin_init!(Self {
375 work <- Opaque::ffi_init(|slot| {
376 // SAFETY: The `WorkItemPointer` implementation promises that `run` can be used as
377 // the work item function.
378 unsafe {
379 bindings::init_work_with_key(
380 slot,
381 Some(T::Pointer::run),
382 false,
383 name.as_char_ptr(),
384 key.as_ptr(),
385 )
386 }
387 }),
388 _inner: PhantomData,
389 })
390 }
391
392 /// Get a pointer to the inner `work_struct`.
393 ///
394 /// # Safety
395 ///
396 /// The provided pointer must not be dangling and must be properly aligned. (But the memory
397 /// need not be initialized.)
398 #[inline]
399 pub unsafe fn raw_get(ptr: *const Self) -> *mut bindings::work_struct {
400 // SAFETY: The caller promises that the pointer is aligned and not dangling.
401 //
402 // A pointer cast would also be ok due to `#[repr(transparent)]`. We use `addr_of!` so that
403 // the compiler does not complain that the `work` field is unused.
404 unsafe { Opaque::raw_get(core::ptr::addr_of!((*ptr).work)) }
405 }
406}
407
408/// Declares that a type has a [`Work<T, ID>`] field.
409///
410/// The intended way of using this trait is via the [`impl_has_work!`] macro. You can use the macro
411/// like this:
412///
413/// ```no_run
414/// use kernel::workqueue::{impl_has_work, Work};
415///
416/// struct MyWorkItem {
417/// work_field: Work<MyWorkItem, 1>,
418/// }
419///
420/// impl_has_work! {
421/// impl HasWork<MyWorkItem, 1> for MyWorkItem { self.work_field }
422/// }
423/// ```
424///
425/// Note that since the [`Work`] type is annotated with an id, you can have several `work_struct`
426/// fields by using a different id for each one.
427///
428/// # Safety
429///
430/// The [`OFFSET`] constant must be the offset of a field in `Self` of type [`Work<T, ID>`]. The
431/// methods on this trait must have exactly the behavior that the definitions given below have.
432///
433/// [`impl_has_work!`]: crate::impl_has_work
434/// [`OFFSET`]: HasWork::OFFSET
435pub unsafe trait HasWork<T, const ID: u64 = 0> {
436 /// The offset of the [`Work<T, ID>`] field.
437 const OFFSET: usize;
438
439 /// Returns the offset of the [`Work<T, ID>`] field.
440 ///
441 /// This method exists because the [`OFFSET`] constant cannot be accessed if the type is not
442 /// [`Sized`].
443 ///
444 /// [`OFFSET`]: HasWork::OFFSET
445 #[inline]
446 fn get_work_offset(&self) -> usize {
447 Self::OFFSET
448 }
449
450 /// Returns a pointer to the [`Work<T, ID>`] field.
451 ///
452 /// # Safety
453 ///
454 /// The provided pointer must point at a valid struct of type `Self`.
455 #[inline]
456 unsafe fn raw_get_work(ptr: *mut Self) -> *mut Work<T, ID> {
457 // SAFETY: The caller promises that the pointer is valid.
458 unsafe { (ptr as *mut u8).add(Self::OFFSET) as *mut Work<T, ID> }
459 }
460
461 /// Returns a pointer to the struct containing the [`Work<T, ID>`] field.
462 ///
463 /// # Safety
464 ///
465 /// The pointer must point at a [`Work<T, ID>`] field in a struct of type `Self`.
466 #[inline]
467 unsafe fn work_container_of(ptr: *mut Work<T, ID>) -> *mut Self
468 where
469 Self: Sized,
470 {
471 // SAFETY: The caller promises that the pointer points at a field of the right type in the
472 // right kind of struct.
473 unsafe { (ptr as *mut u8).sub(Self::OFFSET) as *mut Self }
474 }
475}
476
477/// Used to safely implement the [`HasWork<T, ID>`] trait.
478///
479/// # Examples
480///
481/// ```
482/// use kernel::sync::Arc;
483/// use kernel::workqueue::{self, impl_has_work, Work};
484///
485/// struct MyStruct<'a, T, const N: usize> {
486/// work_field: Work<MyStruct<'a, T, N>, 17>,
487/// f: fn(&'a [T; N]),
488/// }
489///
490/// impl_has_work! {
491/// impl{'a, T, const N: usize} HasWork<MyStruct<'a, T, N>, 17>
492/// for MyStruct<'a, T, N> { self.work_field }
493/// }
494/// ```
495#[macro_export]
496macro_rules! impl_has_work {
497 ($(impl$({$($generics:tt)*})?
498 HasWork<$work_type:ty $(, $id:tt)?>
499 for $self:ty
500 { self.$field:ident }
501 )*) => {$(
502 // SAFETY: The implementation of `raw_get_work` only compiles if the field has the right
503 // type.
504 unsafe impl$(<$($generics)+>)? $crate::workqueue::HasWork<$work_type $(, $id)?> for $self {
505 const OFFSET: usize = ::core::mem::offset_of!(Self, $field) as usize;
506
507 #[inline]
508 unsafe fn raw_get_work(ptr: *mut Self) -> *mut $crate::workqueue::Work<$work_type $(, $id)?> {
509 // SAFETY: The caller promises that the pointer is not dangling.
510 unsafe {
511 ::core::ptr::addr_of_mut!((*ptr).$field)
512 }
513 }
514 }
515 )*};
516}
517pub use impl_has_work;
518
519impl_has_work! {
520 impl{T} HasWork<Self> for ClosureWork<T> { self.work }
521}
522
523unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Arc<T>
524where
525 T: WorkItem<ID, Pointer = Self>,
526 T: HasWork<T, ID>,
527{
528 unsafe extern "C" fn run(ptr: *mut bindings::work_struct) {
529 // SAFETY: The `__enqueue` method always uses a `work_struct` stored in a `Work<T, ID>`.
530 let ptr = ptr as *mut Work<T, ID>;
531 // SAFETY: This computes the pointer that `__enqueue` got from `Arc::into_raw`.
532 let ptr = unsafe { T::work_container_of(ptr) };
533 // SAFETY: This pointer comes from `Arc::into_raw` and we've been given back ownership.
534 let arc = unsafe { Arc::from_raw(ptr) };
535
536 T::run(arc)
537 }
538}
539
540unsafe impl<T, const ID: u64> RawWorkItem<ID> for Arc<T>
541where
542 T: WorkItem<ID, Pointer = Self>,
543 T: HasWork<T, ID>,
544{
545 type EnqueueOutput = Result<(), Self>;
546
547 unsafe fn __enqueue<F>(self, queue_work_on: F) -> Self::EnqueueOutput
548 where
549 F: FnOnce(*mut bindings::work_struct) -> bool,
550 {
551 // Casting between const and mut is not a problem as long as the pointer is a raw pointer.
552 let ptr = Arc::into_raw(self).cast_mut();
553
554 // SAFETY: Pointers into an `Arc` point at a valid value.
555 let work_ptr = unsafe { T::raw_get_work(ptr) };
556 // SAFETY: `raw_get_work` returns a pointer to a valid value.
557 let work_ptr = unsafe { Work::raw_get(work_ptr) };
558
559 if queue_work_on(work_ptr) {
560 Ok(())
561 } else {
562 // SAFETY: The work queue has not taken ownership of the pointer.
563 Err(unsafe { Arc::from_raw(ptr) })
564 }
565 }
566}
567
568unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Pin<Box<T>>
569where
570 T: WorkItem<ID, Pointer = Self>,
571 T: HasWork<T, ID>,
572{
573 unsafe extern "C" fn run(ptr: *mut bindings::work_struct) {
574 // SAFETY: The `__enqueue` method always uses a `work_struct` stored in a `Work<T, ID>`.
575 let ptr = ptr as *mut Work<T, ID>;
576 // SAFETY: This computes the pointer that `__enqueue` got from `Arc::into_raw`.
577 let ptr = unsafe { T::work_container_of(ptr) };
578 // SAFETY: This pointer comes from `Arc::into_raw` and we've been given back ownership.
579 let boxed = unsafe { Box::from_raw(ptr) };
580 // SAFETY: The box was already pinned when it was enqueued.
581 let pinned = unsafe { Pin::new_unchecked(boxed) };
582
583 T::run(pinned)
584 }
585}
586
587unsafe impl<T, const ID: u64> RawWorkItem<ID> for Pin<Box<T>>
588where
589 T: WorkItem<ID, Pointer = Self>,
590 T: HasWork<T, ID>,
591{
592 type EnqueueOutput = ();
593
594 unsafe fn __enqueue<F>(self, queue_work_on: F) -> Self::EnqueueOutput
595 where
596 F: FnOnce(*mut bindings::work_struct) -> bool,
597 {
598 // SAFETY: We're not going to move `self` or any of its fields, so its okay to temporarily
599 // remove the `Pin` wrapper.
600 let boxed = unsafe { Pin::into_inner_unchecked(self) };
601 let ptr = Box::into_raw(boxed);
602
603 // SAFETY: Pointers into a `Box` point at a valid value.
604 let work_ptr = unsafe { T::raw_get_work(ptr) };
605 // SAFETY: `raw_get_work` returns a pointer to a valid value.
606 let work_ptr = unsafe { Work::raw_get(work_ptr) };
607
608 if !queue_work_on(work_ptr) {
609 // SAFETY: This method requires exclusive ownership of the box, so it cannot be in a
610 // workqueue.
611 unsafe { ::core::hint::unreachable_unchecked() }
612 }
613 }
614}
615
616/// Returns the system work queue (`system_wq`).
617///
618/// It is the one used by `schedule[_delayed]_work[_on]()`. Multi-CPU multi-threaded. There are
619/// users which expect relatively short queue flush time.
620///
621/// Callers shouldn't queue work items which can run for too long.
622pub fn system() -> &'static Queue {
623 // SAFETY: `system_wq` is a C global, always available.
624 unsafe { Queue::from_raw(bindings::system_wq) }
625}
626
627/// Returns the system high-priority work queue (`system_highpri_wq`).
628///
629/// It is similar to the one returned by [`system`] but for work items which require higher
630/// scheduling priority.
631pub fn system_highpri() -> &'static Queue {
632 // SAFETY: `system_highpri_wq` is a C global, always available.
633 unsafe { Queue::from_raw(bindings::system_highpri_wq) }
634}
635
636/// Returns the system work queue for potentially long-running work items (`system_long_wq`).
637///
638/// It is similar to the one returned by [`system`] but may host long running work items. Queue
639/// flushing might take relatively long.
640pub fn system_long() -> &'static Queue {
641 // SAFETY: `system_long_wq` is a C global, always available.
642 unsafe { Queue::from_raw(bindings::system_long_wq) }
643}
644
645/// Returns the system unbound work queue (`system_unbound_wq`).
646///
647/// Workers are not bound to any specific CPU, not concurrency managed, and all queued work items
648/// are executed immediately as long as `max_active` limit is not reached and resources are
649/// available.
650pub fn system_unbound() -> &'static Queue {
651 // SAFETY: `system_unbound_wq` is a C global, always available.
652 unsafe { Queue::from_raw(bindings::system_unbound_wq) }
653}
654
655/// Returns the system freezable work queue (`system_freezable_wq`).
656///
657/// It is equivalent to the one returned by [`system`] except that it's freezable.
658///
659/// A freezable workqueue participates in the freeze phase of the system suspend operations. Work
660/// items on the workqueue are drained and no new work item starts execution until thawed.
661pub fn system_freezable() -> &'static Queue {
662 // SAFETY: `system_freezable_wq` is a C global, always available.
663 unsafe { Queue::from_raw(bindings::system_freezable_wq) }
664}
665
666/// Returns the system power-efficient work queue (`system_power_efficient_wq`).
667///
668/// It is inclined towards saving power and is converted to "unbound" variants if the
669/// `workqueue.power_efficient` kernel parameter is specified; otherwise, it is similar to the one
670/// returned by [`system`].
671pub fn system_power_efficient() -> &'static Queue {
672 // SAFETY: `system_power_efficient_wq` is a C global, always available.
673 unsafe { Queue::from_raw(bindings::system_power_efficient_wq) }
674}
675
676/// Returns the system freezable power-efficient work queue (`system_freezable_power_efficient_wq`).
677///
678/// It is similar to the one returned by [`system_power_efficient`] except that is freezable.
679///
680/// A freezable workqueue participates in the freeze phase of the system suspend operations. Work
681/// items on the workqueue are drained and no new work item starts execution until thawed.
682pub fn system_freezable_power_efficient() -> &'static Queue {
683 // SAFETY: `system_freezable_power_efficient_wq` is a C global, always available.
684 unsafe { Queue::from_raw(bindings::system_freezable_power_efficient_wq) }
685}