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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//! ## Examples
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: {}\n", 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//! # print_later(MyStruct::new(42).unwrap());
73//! ```
74//!
75//! The following example shows how multiple `work_struct` fields can be used:
76//!
77//! ```
78//! use kernel::sync::Arc;
79//! use kernel::workqueue::{self, impl_has_work, new_work, Work, WorkItem};
80//!
81//! #[pin_data]
82//! struct MyStruct {
83//! value_1: i32,
84//! value_2: i32,
85//! #[pin]
86//! work_1: Work<MyStruct, 1>,
87//! #[pin]
88//! work_2: Work<MyStruct, 2>,
89//! }
90//!
91//! impl_has_work! {
92//! impl HasWork<Self, 1> for MyStruct { self.work_1 }
93//! impl HasWork<Self, 2> for MyStruct { self.work_2 }
94//! }
95//!
96//! impl MyStruct {
97//! fn new(value_1: i32, value_2: i32) -> Result<Arc<Self>> {
98//! Arc::pin_init(pin_init!(MyStruct {
99//! value_1,
100//! value_2,
101//! work_1 <- new_work!("MyStruct::work_1"),
102//! work_2 <- new_work!("MyStruct::work_2"),
103//! }), GFP_KERNEL)
104//! }
105//! }
106//!
107//! impl WorkItem<1> for MyStruct {
108//! type Pointer = Arc<MyStruct>;
109//!
110//! fn run(this: Arc<MyStruct>) {
111//! pr_info!("The value is: {}\n", this.value_1);
112//! }
113//! }
114//!
115//! impl WorkItem<2> for MyStruct {
116//! type Pointer = Arc<MyStruct>;
117//!
118//! fn run(this: Arc<MyStruct>) {
119//! pr_info!("The second value is: {}\n", this.value_2);
120//! }
121//! }
122//!
123//! fn print_1_later(val: Arc<MyStruct>) {
124//! let _ = workqueue::system().enqueue::<Arc<MyStruct>, 1>(val);
125//! }
126//!
127//! fn print_2_later(val: Arc<MyStruct>) {
128//! let _ = workqueue::system().enqueue::<Arc<MyStruct>, 2>(val);
129//! }
130//! # print_1_later(MyStruct::new(24, 25).unwrap());
131//! # print_2_later(MyStruct::new(41, 42).unwrap());
132//! ```
133//!
134//! This example shows how you can schedule delayed work items:
135//!
136//! ```
137//! use kernel::sync::Arc;
138//! use kernel::workqueue::{self, impl_has_delayed_work, new_delayed_work, DelayedWork, WorkItem};
139//!
140//! #[pin_data]
141//! struct MyStruct {
142//! value: i32,
143//! #[pin]
144//! work: DelayedWork<MyStruct>,
145//! }
146//!
147//! impl_has_delayed_work! {
148//! impl HasDelayedWork<Self> for MyStruct { self.work }
149//! }
150//!
151//! impl MyStruct {
152//! fn new(value: i32) -> Result<Arc<Self>> {
153//! Arc::pin_init(
154//! pin_init!(MyStruct {
155//! value,
156//! work <- new_delayed_work!("MyStruct::work"),
157//! }),
158//! GFP_KERNEL,
159//! )
160//! }
161//! }
162//!
163//! impl WorkItem for MyStruct {
164//! type Pointer = Arc<MyStruct>;
165//!
166//! fn run(this: Arc<MyStruct>) {
167//! pr_info!("The value is: {}\n", this.value);
168//! }
169//! }
170//!
171//! /// This method will enqueue the struct for execution on the system workqueue, where its value
172//! /// will be printed 12 jiffies later.
173//! fn print_later(val: Arc<MyStruct>) {
174//! let _ = workqueue::system().enqueue_delayed(val, 12);
175//! }
176//!
177//! /// It is also possible to use the ordinary `enqueue` method together with `DelayedWork`. This
178//! /// is equivalent to calling `enqueue_delayed` with a delay of zero.
179//! fn print_now(val: Arc<MyStruct>) {
180//! let _ = workqueue::system().enqueue(val);
181//! }
182//! # print_later(MyStruct::new(42).unwrap());
183//! # print_now(MyStruct::new(42).unwrap());
184//! ```
185//!
186//! C header: [`include/linux/workqueue.h`](srctree/include/linux/workqueue.h)
187
188use crate::{
189 alloc::{AllocError, Flags},
190 container_of,
191 prelude::*,
192 sync::Arc,
193 sync::LockClassKey,
194 time::Jiffies,
195 types::Opaque,
196};
197use core::marker::PhantomData;
198
199/// Creates a [`Work`] initialiser with the given name and a newly-created lock class.
200#[macro_export]
201macro_rules! new_work {
202 ($($name:literal)?) => {
203 $crate::workqueue::Work::new($crate::optional_name!($($name)?), $crate::static_lock_class!())
204 };
205}
206pub use new_work;
207
208/// Creates a [`DelayedWork`] initialiser with the given name and a newly-created lock class.
209#[macro_export]
210macro_rules! new_delayed_work {
211 () => {
212 $crate::workqueue::DelayedWork::new(
213 $crate::optional_name!(),
214 $crate::static_lock_class!(),
215 $crate::c_str!(::core::concat!(
216 ::core::file!(),
217 ":",
218 ::core::line!(),
219 "_timer"
220 )),
221 $crate::static_lock_class!(),
222 )
223 };
224 ($name:literal) => {
225 $crate::workqueue::DelayedWork::new(
226 $crate::c_str!($name),
227 $crate::static_lock_class!(),
228 $crate::c_str!(::core::concat!($name, "_timer")),
229 $crate::static_lock_class!(),
230 )
231 };
232}
233pub use new_delayed_work;
234
235/// A kernel work queue.
236///
237/// Wraps the kernel's C `struct workqueue_struct`.
238///
239/// It allows work items to be queued to run on thread pools managed by the kernel. Several are
240/// always available, for example, `system`, `system_highpri`, `system_long`, etc.
241#[repr(transparent)]
242pub struct Queue(Opaque<bindings::workqueue_struct>);
243
244// SAFETY: Accesses to workqueues used by [`Queue`] are thread-safe.
245unsafe impl Send for Queue {}
246// SAFETY: Accesses to workqueues used by [`Queue`] are thread-safe.
247unsafe impl Sync for Queue {}
248
249impl Queue {
250 /// Use the provided `struct workqueue_struct` with Rust.
251 ///
252 /// # Safety
253 ///
254 /// The caller must ensure that the provided raw pointer is not dangling, that it points at a
255 /// valid workqueue, and that it remains valid until the end of `'a`.
256 pub unsafe fn from_raw<'a>(ptr: *const bindings::workqueue_struct) -> &'a Queue {
257 // SAFETY: The `Queue` type is `#[repr(transparent)]`, so the pointer cast is valid. The
258 // caller promises that the pointer is not dangling.
259 unsafe { &*ptr.cast::<Queue>() }
260 }
261
262 /// Enqueues a work item.
263 ///
264 /// This may fail if the work item is already enqueued in a workqueue.
265 ///
266 /// The work item will be submitted using `WORK_CPU_UNBOUND`.
267 pub fn enqueue<W, const ID: u64>(&self, w: W) -> W::EnqueueOutput
268 where
269 W: RawWorkItem<ID> + Send + 'static,
270 {
271 let queue_ptr = self.0.get();
272
273 // SAFETY: We only return `false` if the `work_struct` is already in a workqueue. The other
274 // `__enqueue` requirements are not relevant since `W` is `Send` and static.
275 //
276 // The call to `bindings::queue_work_on` will dereference the provided raw pointer, which
277 // is ok because `__enqueue` guarantees that the pointer is valid for the duration of this
278 // closure.
279 //
280 // Furthermore, if the C workqueue code accesses the pointer after this call to
281 // `__enqueue`, then the work item was successfully enqueued, and `bindings::queue_work_on`
282 // will have returned true. In this case, `__enqueue` promises that the raw pointer will
283 // stay valid until we call the function pointer in the `work_struct`, so the access is ok.
284 unsafe {
285 w.__enqueue(move |work_ptr| {
286 bindings::queue_work_on(
287 bindings::wq_misc_consts_WORK_CPU_UNBOUND as ffi::c_int,
288 queue_ptr,
289 work_ptr,
290 )
291 })
292 }
293 }
294
295 /// Enqueues a delayed work item.
296 ///
297 /// This may fail if the work item is already enqueued in a workqueue.
298 ///
299 /// The work item will be submitted using `WORK_CPU_UNBOUND`.
300 pub fn enqueue_delayed<W, const ID: u64>(&self, w: W, delay: Jiffies) -> W::EnqueueOutput
301 where
302 W: RawDelayedWorkItem<ID> + Send + 'static,
303 {
304 let queue_ptr = self.0.get();
305
306 // SAFETY: We only return `false` if the `work_struct` is already in a workqueue. The other
307 // `__enqueue` requirements are not relevant since `W` is `Send` and static.
308 //
309 // The call to `bindings::queue_delayed_work_on` will dereference the provided raw pointer,
310 // which is ok because `__enqueue` guarantees that the pointer is valid for the duration of
311 // this closure, and the safety requirements of `RawDelayedWorkItem` expands this
312 // requirement to apply to the entire `delayed_work`.
313 //
314 // Furthermore, if the C workqueue code accesses the pointer after this call to
315 // `__enqueue`, then the work item was successfully enqueued, and
316 // `bindings::queue_delayed_work_on` will have returned true. In this case, `__enqueue`
317 // promises that the raw pointer will stay valid until we call the function pointer in the
318 // `work_struct`, so the access is ok.
319 unsafe {
320 w.__enqueue(move |work_ptr| {
321 bindings::queue_delayed_work_on(
322 bindings::wq_misc_consts_WORK_CPU_UNBOUND as ffi::c_int,
323 queue_ptr,
324 container_of!(work_ptr, bindings::delayed_work, work),
325 delay,
326 )
327 })
328 }
329 }
330
331 /// Tries to spawn the given function or closure as a work item.
332 ///
333 /// This method can fail because it allocates memory to store the work item.
334 pub fn try_spawn<T: 'static + Send + FnOnce()>(
335 &self,
336 flags: Flags,
337 func: T,
338 ) -> Result<(), AllocError> {
339 let init = pin_init!(ClosureWork {
340 work <- new_work!("Queue::try_spawn"),
341 func: Some(func),
342 });
343
344 self.enqueue(KBox::pin_init(init, flags).map_err(|_| AllocError)?);
345 Ok(())
346 }
347}
348
349/// A helper type used in [`try_spawn`].
350///
351/// [`try_spawn`]: Queue::try_spawn
352#[pin_data]
353struct ClosureWork<T> {
354 #[pin]
355 work: Work<ClosureWork<T>>,
356 func: Option<T>,
357}
358
359impl<T: FnOnce()> WorkItem for ClosureWork<T> {
360 type Pointer = Pin<KBox<Self>>;
361
362 fn run(mut this: Pin<KBox<Self>>) {
363 if let Some(func) = this.as_mut().project().func.take() {
364 (func)()
365 }
366 }
367}
368
369/// A raw work item.
370///
371/// This is the low-level trait that is designed for being as general as possible.
372///
373/// The `ID` parameter to this trait exists so that a single type can provide multiple
374/// implementations of this trait. For example, if a struct has multiple `work_struct` fields, then
375/// you will implement this trait once for each field, using a different id for each field. The
376/// actual value of the id is not important as long as you use different ids for different fields
377/// of the same struct. (Fields of different structs need not use different ids.)
378///
379/// Note that the id is used only to select the right method to call during compilation. It won't be
380/// part of the final executable.
381///
382/// # Safety
383///
384/// Implementers must ensure that any pointers passed to a `queue_work_on` closure by [`__enqueue`]
385/// remain valid for the duration specified in the guarantees section of the documentation for
386/// [`__enqueue`].
387///
388/// [`__enqueue`]: RawWorkItem::__enqueue
389pub unsafe trait RawWorkItem<const ID: u64> {
390 /// The return type of [`Queue::enqueue`].
391 type EnqueueOutput;
392
393 /// Enqueues this work item on a queue using the provided `queue_work_on` method.
394 ///
395 /// # Guarantees
396 ///
397 /// If this method calls the provided closure, then the raw pointer is guaranteed to point at a
398 /// valid `work_struct` for the duration of the call to the closure. If the closure returns
399 /// true, then it is further guaranteed that the pointer remains valid until someone calls the
400 /// function pointer stored in the `work_struct`.
401 ///
402 /// # Safety
403 ///
404 /// The provided closure may only return `false` if the `work_struct` is already in a workqueue.
405 ///
406 /// If the work item type is annotated with any lifetimes, then you must not call the function
407 /// pointer after any such lifetime expires. (Never calling the function pointer is okay.)
408 ///
409 /// If the work item type is not [`Send`], then the function pointer must be called on the same
410 /// thread as the call to `__enqueue`.
411 unsafe fn __enqueue<F>(self, queue_work_on: F) -> Self::EnqueueOutput
412 where
413 F: FnOnce(*mut bindings::work_struct) -> bool;
414}
415
416/// A raw delayed work item.
417///
418/// # Safety
419///
420/// If the `__enqueue` method in the `RawWorkItem` implementation calls the closure, then the
421/// provided pointer must point at the `work` field of a valid `delayed_work`, and the guarantees
422/// that `__enqueue` provides about accessing the `work_struct` must also apply to the rest of the
423/// `delayed_work` struct.
424pub unsafe trait RawDelayedWorkItem<const ID: u64>: RawWorkItem<ID> {}
425
426/// Defines the method that should be called directly when a work item is executed.
427///
428/// This trait is implemented by `Pin<KBox<T>>` and [`Arc<T>`], and is mainly intended to be
429/// implemented for smart pointer types. For your own structs, you would implement [`WorkItem`]
430/// instead. The [`run`] method on this trait will usually just perform the appropriate
431/// `container_of` translation and then call into the [`run`][WorkItem::run] method from the
432/// [`WorkItem`] trait.
433///
434/// This trait is used when the `work_struct` field is defined using the [`Work`] helper.
435///
436/// # Safety
437///
438/// Implementers must ensure that [`__enqueue`] uses a `work_struct` initialized with the [`run`]
439/// method of this trait as the function pointer.
440///
441/// [`__enqueue`]: RawWorkItem::__enqueue
442/// [`run`]: WorkItemPointer::run
443pub unsafe trait WorkItemPointer<const ID: u64>: RawWorkItem<ID> {
444 /// Run this work item.
445 ///
446 /// # Safety
447 ///
448 /// The provided `work_struct` pointer must originate from a previous call to [`__enqueue`]
449 /// where the `queue_work_on` closure returned true, and the pointer must still be valid.
450 ///
451 /// [`__enqueue`]: RawWorkItem::__enqueue
452 unsafe extern "C" fn run(ptr: *mut bindings::work_struct);
453}
454
455/// Defines the method that should be called when this work item is executed.
456///
457/// This trait is used when the `work_struct` field is defined using the [`Work`] helper.
458pub trait WorkItem<const ID: u64 = 0> {
459 /// The pointer type that this struct is wrapped in. This will typically be `Arc<Self>` or
460 /// `Pin<KBox<Self>>`.
461 type Pointer: WorkItemPointer<ID>;
462
463 /// The method that should be called when this work item is executed.
464 fn run(this: Self::Pointer);
465}
466
467/// Links for a work item.
468///
469/// This struct contains a function pointer to the [`run`] function from the [`WorkItemPointer`]
470/// trait, and defines the linked list pointers necessary to enqueue a work item in a workqueue.
471///
472/// Wraps the kernel's C `struct work_struct`.
473///
474/// This is a helper type used to associate a `work_struct` with the [`WorkItem`] that uses it.
475///
476/// [`run`]: WorkItemPointer::run
477#[pin_data]
478#[repr(transparent)]
479pub struct Work<T: ?Sized, const ID: u64 = 0> {
480 #[pin]
481 work: Opaque<bindings::work_struct>,
482 _inner: PhantomData<T>,
483}
484
485// SAFETY: Kernel work items are usable from any thread.
486//
487// We do not need to constrain `T` since the work item does not actually contain a `T`.
488unsafe impl<T: ?Sized, const ID: u64> Send for Work<T, ID> {}
489// SAFETY: Kernel work items are usable from any thread.
490//
491// We do not need to constrain `T` since the work item does not actually contain a `T`.
492unsafe impl<T: ?Sized, const ID: u64> Sync for Work<T, ID> {}
493
494impl<T: ?Sized, const ID: u64> Work<T, ID> {
495 /// Creates a new instance of [`Work`].
496 #[inline]
497 pub fn new(name: &'static CStr, key: Pin<&'static LockClassKey>) -> impl PinInit<Self>
498 where
499 T: WorkItem<ID>,
500 {
501 pin_init!(Self {
502 work <- Opaque::ffi_init(|slot| {
503 // SAFETY: The `WorkItemPointer` implementation promises that `run` can be used as
504 // the work item function.
505 unsafe {
506 bindings::init_work_with_key(
507 slot,
508 Some(T::Pointer::run),
509 false,
510 name.as_char_ptr(),
511 key.as_ptr(),
512 )
513 }
514 }),
515 _inner: PhantomData,
516 })
517 }
518
519 /// Get a pointer to the inner `work_struct`.
520 ///
521 /// # Safety
522 ///
523 /// The provided pointer must not be dangling and must be properly aligned. (But the memory
524 /// need not be initialized.)
525 #[inline]
526 pub unsafe fn raw_get(ptr: *const Self) -> *mut bindings::work_struct {
527 // SAFETY: The caller promises that the pointer is aligned and not dangling.
528 //
529 // A pointer cast would also be ok due to `#[repr(transparent)]`. We use `addr_of!` so that
530 // the compiler does not complain that the `work` field is unused.
531 unsafe { Opaque::cast_into(core::ptr::addr_of!((*ptr).work)) }
532 }
533}
534
535/// Declares that a type contains a [`Work<T, ID>`].
536///
537/// The intended way of using this trait is via the [`impl_has_work!`] macro. You can use the macro
538/// like this:
539///
540/// ```no_run
541/// use kernel::workqueue::{impl_has_work, Work};
542///
543/// struct MyWorkItem {
544/// work_field: Work<MyWorkItem, 1>,
545/// }
546///
547/// impl_has_work! {
548/// impl HasWork<MyWorkItem, 1> for MyWorkItem { self.work_field }
549/// }
550/// ```
551///
552/// Note that since the [`Work`] type is annotated with an id, you can have several `work_struct`
553/// fields by using a different id for each one.
554///
555/// # Safety
556///
557/// The methods [`raw_get_work`] and [`work_container_of`] must return valid pointers and must be
558/// true inverses of each other; that is, they must satisfy the following invariants:
559/// - `work_container_of(raw_get_work(ptr)) == ptr` for any `ptr: *mut Self`.
560/// - `raw_get_work(work_container_of(ptr)) == ptr` for any `ptr: *mut Work<T, ID>`.
561///
562/// [`impl_has_work!`]: crate::impl_has_work
563/// [`raw_get_work`]: HasWork::raw_get_work
564/// [`work_container_of`]: HasWork::work_container_of
565pub unsafe trait HasWork<T, const ID: u64 = 0> {
566 /// Returns a pointer to the [`Work<T, ID>`] field.
567 ///
568 /// # Safety
569 ///
570 /// The provided pointer must point at a valid struct of type `Self`.
571 unsafe fn raw_get_work(ptr: *mut Self) -> *mut Work<T, ID>;
572
573 /// Returns a pointer to the struct containing the [`Work<T, ID>`] field.
574 ///
575 /// # Safety
576 ///
577 /// The pointer must point at a [`Work<T, ID>`] field in a struct of type `Self`.
578 unsafe fn work_container_of(ptr: *mut Work<T, ID>) -> *mut Self;
579}
580
581/// Used to safely implement the [`HasWork<T, ID>`] trait.
582///
583/// # Examples
584///
585/// ```
586/// use kernel::sync::Arc;
587/// use kernel::workqueue::{self, impl_has_work, Work};
588///
589/// struct MyStruct<'a, T, const N: usize> {
590/// work_field: Work<MyStruct<'a, T, N>, 17>,
591/// f: fn(&'a [T; N]),
592/// }
593///
594/// impl_has_work! {
595/// impl{'a, T, const N: usize} HasWork<MyStruct<'a, T, N>, 17>
596/// for MyStruct<'a, T, N> { self.work_field }
597/// }
598/// ```
599#[macro_export]
600macro_rules! impl_has_work {
601 ($(impl$({$($generics:tt)*})?
602 HasWork<$work_type:ty $(, $id:tt)?>
603 for $self:ty
604 { self.$field:ident }
605 )*) => {$(
606 // SAFETY: The implementation of `raw_get_work` only compiles if the field has the right
607 // type.
608 unsafe impl$(<$($generics)+>)? $crate::workqueue::HasWork<$work_type $(, $id)?> for $self {
609 #[inline]
610 unsafe fn raw_get_work(ptr: *mut Self) -> *mut $crate::workqueue::Work<$work_type $(, $id)?> {
611 // SAFETY: The caller promises that the pointer is not dangling.
612 unsafe {
613 ::core::ptr::addr_of_mut!((*ptr).$field)
614 }
615 }
616
617 #[inline]
618 unsafe fn work_container_of(
619 ptr: *mut $crate::workqueue::Work<$work_type $(, $id)?>,
620 ) -> *mut Self {
621 // SAFETY: The caller promises that the pointer points at a field of the right type
622 // in the right kind of struct.
623 unsafe { $crate::container_of!(ptr, Self, $field) }
624 }
625 }
626 )*};
627}
628pub use impl_has_work;
629
630impl_has_work! {
631 impl{T} HasWork<Self> for ClosureWork<T> { self.work }
632}
633
634/// Links for a delayed work item.
635///
636/// This struct contains a function pointer to the [`run`] function from the [`WorkItemPointer`]
637/// trait, and defines the linked list pointers necessary to enqueue a work item in a workqueue in
638/// a delayed manner.
639///
640/// Wraps the kernel's C `struct delayed_work`.
641///
642/// This is a helper type used to associate a `delayed_work` with the [`WorkItem`] that uses it.
643///
644/// [`run`]: WorkItemPointer::run
645#[pin_data]
646#[repr(transparent)]
647pub struct DelayedWork<T: ?Sized, const ID: u64 = 0> {
648 #[pin]
649 dwork: Opaque<bindings::delayed_work>,
650 _inner: PhantomData<T>,
651}
652
653// SAFETY: Kernel work items are usable from any thread.
654//
655// We do not need to constrain `T` since the work item does not actually contain a `T`.
656unsafe impl<T: ?Sized, const ID: u64> Send for DelayedWork<T, ID> {}
657// SAFETY: Kernel work items are usable from any thread.
658//
659// We do not need to constrain `T` since the work item does not actually contain a `T`.
660unsafe impl<T: ?Sized, const ID: u64> Sync for DelayedWork<T, ID> {}
661
662impl<T: ?Sized, const ID: u64> DelayedWork<T, ID> {
663 /// Creates a new instance of [`DelayedWork`].
664 #[inline]
665 pub fn new(
666 work_name: &'static CStr,
667 work_key: Pin<&'static LockClassKey>,
668 timer_name: &'static CStr,
669 timer_key: Pin<&'static LockClassKey>,
670 ) -> impl PinInit<Self>
671 where
672 T: WorkItem<ID>,
673 {
674 pin_init!(Self {
675 dwork <- Opaque::ffi_init(|slot: *mut bindings::delayed_work| {
676 // SAFETY: The `WorkItemPointer` implementation promises that `run` can be used as
677 // the work item function.
678 unsafe {
679 bindings::init_work_with_key(
680 core::ptr::addr_of_mut!((*slot).work),
681 Some(T::Pointer::run),
682 false,
683 work_name.as_char_ptr(),
684 work_key.as_ptr(),
685 )
686 }
687
688 // SAFETY: The `delayed_work_timer_fn` function pointer can be used here because
689 // the timer is embedded in a `struct delayed_work`, and only ever scheduled via
690 // the core workqueue code, and configured to run in irqsafe context.
691 unsafe {
692 bindings::timer_init_key(
693 core::ptr::addr_of_mut!((*slot).timer),
694 Some(bindings::delayed_work_timer_fn),
695 bindings::TIMER_IRQSAFE,
696 timer_name.as_char_ptr(),
697 timer_key.as_ptr(),
698 )
699 }
700 }),
701 _inner: PhantomData,
702 })
703 }
704
705 /// Get a pointer to the inner `delayed_work`.
706 ///
707 /// # Safety
708 ///
709 /// The provided pointer must not be dangling and must be properly aligned. (But the memory
710 /// need not be initialized.)
711 #[inline]
712 pub unsafe fn raw_as_work(ptr: *const Self) -> *mut Work<T, ID> {
713 // SAFETY: The caller promises that the pointer is aligned and not dangling.
714 let dw: *mut bindings::delayed_work =
715 unsafe { Opaque::cast_into(core::ptr::addr_of!((*ptr).dwork)) };
716 // SAFETY: The caller promises that the pointer is aligned and not dangling.
717 let wrk: *mut bindings::work_struct = unsafe { core::ptr::addr_of_mut!((*dw).work) };
718 // CAST: Work and work_struct have compatible layouts.
719 wrk.cast()
720 }
721}
722
723/// Declares that a type contains a [`DelayedWork<T, ID>`].
724///
725/// # Safety
726///
727/// The `HasWork<T, ID>` implementation must return a `work_struct` that is stored in the `work`
728/// field of a `delayed_work` with the same access rules as the `work_struct`.
729pub unsafe trait HasDelayedWork<T, const ID: u64 = 0>: HasWork<T, ID> {}
730
731/// Used to safely implement the [`HasDelayedWork<T, ID>`] trait.
732///
733/// This macro also implements the [`HasWork`] trait, so you do not need to use [`impl_has_work!`]
734/// when using this macro.
735///
736/// # Examples
737///
738/// ```
739/// use kernel::sync::Arc;
740/// use kernel::workqueue::{self, impl_has_delayed_work, DelayedWork};
741///
742/// struct MyStruct<'a, T, const N: usize> {
743/// work_field: DelayedWork<MyStruct<'a, T, N>, 17>,
744/// f: fn(&'a [T; N]),
745/// }
746///
747/// impl_has_delayed_work! {
748/// impl{'a, T, const N: usize} HasDelayedWork<MyStruct<'a, T, N>, 17>
749/// for MyStruct<'a, T, N> { self.work_field }
750/// }
751/// ```
752#[macro_export]
753macro_rules! impl_has_delayed_work {
754 ($(impl$({$($generics:tt)*})?
755 HasDelayedWork<$work_type:ty $(, $id:tt)?>
756 for $self:ty
757 { self.$field:ident }
758 )*) => {$(
759 // SAFETY: The implementation of `raw_get_work` only compiles if the field has the right
760 // type.
761 unsafe impl$(<$($generics)+>)?
762 $crate::workqueue::HasDelayedWork<$work_type $(, $id)?> for $self {}
763
764 // SAFETY: The implementation of `raw_get_work` only compiles if the field has the right
765 // type.
766 unsafe impl$(<$($generics)+>)? $crate::workqueue::HasWork<$work_type $(, $id)?> for $self {
767 #[inline]
768 unsafe fn raw_get_work(
769 ptr: *mut Self
770 ) -> *mut $crate::workqueue::Work<$work_type $(, $id)?> {
771 // SAFETY: The caller promises that the pointer is not dangling.
772 let ptr: *mut $crate::workqueue::DelayedWork<$work_type $(, $id)?> = unsafe {
773 ::core::ptr::addr_of_mut!((*ptr).$field)
774 };
775
776 // SAFETY: The caller promises that the pointer is not dangling.
777 unsafe { $crate::workqueue::DelayedWork::raw_as_work(ptr) }
778 }
779
780 #[inline]
781 unsafe fn work_container_of(
782 ptr: *mut $crate::workqueue::Work<$work_type $(, $id)?>,
783 ) -> *mut Self {
784 // SAFETY: The caller promises that the pointer points at a field of the right type
785 // in the right kind of struct.
786 let ptr = unsafe { $crate::workqueue::Work::raw_get(ptr) };
787
788 // SAFETY: The caller promises that the pointer points at a field of the right type
789 // in the right kind of struct.
790 let delayed_work = unsafe {
791 $crate::container_of!(ptr, $crate::bindings::delayed_work, work)
792 };
793
794 let delayed_work: *mut $crate::workqueue::DelayedWork<$work_type $(, $id)?> =
795 delayed_work.cast();
796
797 // SAFETY: The caller promises that the pointer points at a field of the right type
798 // in the right kind of struct.
799 unsafe { $crate::container_of!(delayed_work, Self, $field) }
800 }
801 }
802 )*};
803}
804pub use impl_has_delayed_work;
805
806// SAFETY: The `__enqueue` implementation in RawWorkItem uses a `work_struct` initialized with the
807// `run` method of this trait as the function pointer because:
808// - `__enqueue` gets the `work_struct` from the `Work` field, using `T::raw_get_work`.
809// - The only safe way to create a `Work` object is through `Work::new`.
810// - `Work::new` makes sure that `T::Pointer::run` is passed to `init_work_with_key`.
811// - Finally `Work` and `RawWorkItem` guarantee that the correct `Work` field
812// will be used because of the ID const generic bound. This makes sure that `T::raw_get_work`
813// uses the correct offset for the `Work` field, and `Work::new` picks the correct
814// implementation of `WorkItemPointer` for `Arc<T>`.
815unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Arc<T>
816where
817 T: WorkItem<ID, Pointer = Self>,
818 T: HasWork<T, ID>,
819{
820 unsafe extern "C" fn run(ptr: *mut bindings::work_struct) {
821 // The `__enqueue` method always uses a `work_struct` stored in a `Work<T, ID>`.
822 let ptr = ptr.cast::<Work<T, ID>>();
823 // SAFETY: This computes the pointer that `__enqueue` got from `Arc::into_raw`.
824 let ptr = unsafe { T::work_container_of(ptr) };
825 // SAFETY: This pointer comes from `Arc::into_raw` and we've been given back ownership.
826 let arc = unsafe { Arc::from_raw(ptr) };
827
828 T::run(arc)
829 }
830}
831
832// SAFETY: The `work_struct` raw pointer is guaranteed to be valid for the duration of the call to
833// the closure because we get it from an `Arc`, which means that the ref count will be at least 1,
834// and we don't drop the `Arc` ourselves. If `queue_work_on` returns true, it is further guaranteed
835// to be valid until a call to the function pointer in `work_struct` because we leak the memory it
836// points to, and only reclaim it if the closure returns false, or in `WorkItemPointer::run`, which
837// is what the function pointer in the `work_struct` must be pointing to, according to the safety
838// requirements of `WorkItemPointer`.
839unsafe impl<T, const ID: u64> RawWorkItem<ID> for Arc<T>
840where
841 T: WorkItem<ID, Pointer = Self>,
842 T: HasWork<T, ID>,
843{
844 type EnqueueOutput = Result<(), Self>;
845
846 unsafe fn __enqueue<F>(self, queue_work_on: F) -> Self::EnqueueOutput
847 where
848 F: FnOnce(*mut bindings::work_struct) -> bool,
849 {
850 // Casting between const and mut is not a problem as long as the pointer is a raw pointer.
851 let ptr = Arc::into_raw(self).cast_mut();
852
853 // SAFETY: Pointers into an `Arc` point at a valid value.
854 let work_ptr = unsafe { T::raw_get_work(ptr) };
855 // SAFETY: `raw_get_work` returns a pointer to a valid value.
856 let work_ptr = unsafe { Work::raw_get(work_ptr) };
857
858 if queue_work_on(work_ptr) {
859 Ok(())
860 } else {
861 // SAFETY: The work queue has not taken ownership of the pointer.
862 Err(unsafe { Arc::from_raw(ptr) })
863 }
864 }
865}
866
867// SAFETY: By the safety requirements of `HasDelayedWork`, the `work_struct` returned by methods in
868// `HasWork` provides a `work_struct` that is the `work` field of a `delayed_work`, and the rest of
869// the `delayed_work` has the same access rules as its `work` field.
870unsafe impl<T, const ID: u64> RawDelayedWorkItem<ID> for Arc<T>
871where
872 T: WorkItem<ID, Pointer = Self>,
873 T: HasDelayedWork<T, ID>,
874{
875}
876
877// SAFETY: TODO.
878unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Pin<KBox<T>>
879where
880 T: WorkItem<ID, Pointer = Self>,
881 T: HasWork<T, ID>,
882{
883 unsafe extern "C" fn run(ptr: *mut bindings::work_struct) {
884 // The `__enqueue` method always uses a `work_struct` stored in a `Work<T, ID>`.
885 let ptr = ptr.cast::<Work<T, ID>>();
886 // SAFETY: This computes the pointer that `__enqueue` got from `Arc::into_raw`.
887 let ptr = unsafe { T::work_container_of(ptr) };
888 // SAFETY: This pointer comes from `Arc::into_raw` and we've been given back ownership.
889 let boxed = unsafe { KBox::from_raw(ptr) };
890 // SAFETY: The box was already pinned when it was enqueued.
891 let pinned = unsafe { Pin::new_unchecked(boxed) };
892
893 T::run(pinned)
894 }
895}
896
897// SAFETY: TODO.
898unsafe impl<T, const ID: u64> RawWorkItem<ID> for Pin<KBox<T>>
899where
900 T: WorkItem<ID, Pointer = Self>,
901 T: HasWork<T, ID>,
902{
903 type EnqueueOutput = ();
904
905 unsafe fn __enqueue<F>(self, queue_work_on: F) -> Self::EnqueueOutput
906 where
907 F: FnOnce(*mut bindings::work_struct) -> bool,
908 {
909 // SAFETY: We're not going to move `self` or any of its fields, so its okay to temporarily
910 // remove the `Pin` wrapper.
911 let boxed = unsafe { Pin::into_inner_unchecked(self) };
912 let ptr = KBox::into_raw(boxed);
913
914 // SAFETY: Pointers into a `KBox` point at a valid value.
915 let work_ptr = unsafe { T::raw_get_work(ptr) };
916 // SAFETY: `raw_get_work` returns a pointer to a valid value.
917 let work_ptr = unsafe { Work::raw_get(work_ptr) };
918
919 if !queue_work_on(work_ptr) {
920 // SAFETY: This method requires exclusive ownership of the box, so it cannot be in a
921 // workqueue.
922 unsafe { ::core::hint::unreachable_unchecked() }
923 }
924 }
925}
926
927// SAFETY: By the safety requirements of `HasDelayedWork`, the `work_struct` returned by methods in
928// `HasWork` provides a `work_struct` that is the `work` field of a `delayed_work`, and the rest of
929// the `delayed_work` has the same access rules as its `work` field.
930unsafe impl<T, const ID: u64> RawDelayedWorkItem<ID> for Pin<KBox<T>>
931where
932 T: WorkItem<ID, Pointer = Self>,
933 T: HasDelayedWork<T, ID>,
934{
935}
936
937/// Returns the system work queue (`system_wq`).
938///
939/// It is the one used by `schedule[_delayed]_work[_on]()`. Multi-CPU multi-threaded. There are
940/// users which expect relatively short queue flush time.
941///
942/// Callers shouldn't queue work items which can run for too long.
943pub fn system() -> &'static Queue {
944 // SAFETY: `system_wq` is a C global, always available.
945 unsafe { Queue::from_raw(bindings::system_wq) }
946}
947
948/// Returns the system high-priority work queue (`system_highpri_wq`).
949///
950/// It is similar to the one returned by [`system`] but for work items which require higher
951/// scheduling priority.
952pub fn system_highpri() -> &'static Queue {
953 // SAFETY: `system_highpri_wq` is a C global, always available.
954 unsafe { Queue::from_raw(bindings::system_highpri_wq) }
955}
956
957/// Returns the system work queue for potentially long-running work items (`system_long_wq`).
958///
959/// It is similar to the one returned by [`system`] but may host long running work items. Queue
960/// flushing might take relatively long.
961pub fn system_long() -> &'static Queue {
962 // SAFETY: `system_long_wq` is a C global, always available.
963 unsafe { Queue::from_raw(bindings::system_long_wq) }
964}
965
966/// Returns the system unbound work queue (`system_unbound_wq`).
967///
968/// Workers are not bound to any specific CPU, not concurrency managed, and all queued work items
969/// are executed immediately as long as `max_active` limit is not reached and resources are
970/// available.
971pub fn system_unbound() -> &'static Queue {
972 // SAFETY: `system_unbound_wq` is a C global, always available.
973 unsafe { Queue::from_raw(bindings::system_unbound_wq) }
974}
975
976/// Returns the system freezable work queue (`system_freezable_wq`).
977///
978/// It is equivalent to the one returned by [`system`] except that it's freezable.
979///
980/// A freezable workqueue participates in the freeze phase of the system suspend operations. Work
981/// items on the workqueue are drained and no new work item starts execution until thawed.
982pub fn system_freezable() -> &'static Queue {
983 // SAFETY: `system_freezable_wq` is a C global, always available.
984 unsafe { Queue::from_raw(bindings::system_freezable_wq) }
985}
986
987/// Returns the system power-efficient work queue (`system_power_efficient_wq`).
988///
989/// It is inclined towards saving power and is converted to "unbound" variants if the
990/// `workqueue.power_efficient` kernel parameter is specified; otherwise, it is similar to the one
991/// returned by [`system`].
992pub fn system_power_efficient() -> &'static Queue {
993 // SAFETY: `system_power_efficient_wq` is a C global, always available.
994 unsafe { Queue::from_raw(bindings::system_power_efficient_wq) }
995}
996
997/// Returns the system freezable power-efficient work queue (`system_freezable_power_efficient_wq`).
998///
999/// It is similar to the one returned by [`system_power_efficient`] except that is freezable.
1000///
1001/// A freezable workqueue participates in the freeze phase of the system suspend operations. Work
1002/// items on the workqueue are drained and no new work item starts execution until thawed.
1003pub fn system_freezable_power_efficient() -> &'static Queue {
1004 // SAFETY: `system_freezable_power_efficient_wq` is a C global, always available.
1005 unsafe { Queue::from_raw(bindings::system_freezable_power_efficient_wq) }
1006}
1007
1008/// Returns the system bottom halves work queue (`system_bh_wq`).
1009///
1010/// It is similar to the one returned by [`system`] but for work items which
1011/// need to run from a softirq context.
1012pub fn system_bh() -> &'static Queue {
1013 // SAFETY: `system_bh_wq` is a C global, always available.
1014 unsafe { Queue::from_raw(bindings::system_bh_wq) }
1015}
1016
1017/// Returns the system bottom halves high-priority work queue (`system_bh_highpri_wq`).
1018///
1019/// It is similar to the one returned by [`system_bh`] but for work items which
1020/// require higher scheduling priority.
1021pub fn system_bh_highpri() -> &'static Queue {
1022 // SAFETY: `system_bh_highpri_wq` is a C global, always available.
1023 unsafe { Queue::from_raw(bindings::system_bh_highpri_wq) }
1024}