// SPDX-License-Identifier: GPL-2.0 //! Work queues.//!//! This file has two components: The raw work item API, and the safe work item API.//!//! One pattern that is used in both APIs is the `ID` const generic, which exists to allow a single//! type to define multiple `work_struct` fields. This is done by choosing an id for each field,//! and using that id to specify which field you wish to use. (The actual value doesn't matter, as//! long as you use different values for different fields of the same struct.) Since these IDs are//! generic, they are used only at compile-time, so they shouldn't exist in the final binary.//!//! # The raw API//!//! The raw API consists of the [`RawWorkItem`] trait, where the work item needs to provide an//! arbitrary function that knows how to enqueue the work item. It should usually not be used//! directly, but if you want to, you can use it without using the pieces from the safe API.//!//! # The safe API//!//! The safe API is used via the [`Work`] struct and [`WorkItem`] traits. Furthermore, it also//! includes a trait called [`WorkItemPointer`], which is usually not used directly by the user.//!//!  * The [`Work`] struct is the Rust wrapper for the C `work_struct` type.//!  * The [`WorkItem`] trait is implemented for structs that can be enqueued to a workqueue.//!  * The [`WorkItemPointer`] trait is implemented for the pointer type that points at a something//!    that implements [`WorkItem`].//!//! ## Example//!//! This example defines a struct that holds an integer and can be scheduled on the workqueue. When//! the struct is executed, it will print the integer. Since there is only one `work_struct` field,//! we do not need to specify ids for the fields.//!//! ```//! use kernel::sync::Arc;//! use kernel::workqueue::{self, impl_has_work, new_work, Work, WorkItem};//!//! #[pin_data]//! struct MyStruct {//!     value: i32,//!     #[pin]//!     work: Work<MyStruct>,//! }//!//! impl_has_work! {//!     impl HasWork<Self> for MyStruct { self.work }//! }//!//! impl MyStruct {//!     fn new(value: i32) -> Result<Arc<Self>> {//!         Arc::pin_init(pin_init!(MyStruct {//!             value,//!             work <- new_work!("MyStruct::work"),//!         }), GFP_KERNEL)//!     }//! }//!//! impl WorkItem for MyStruct {//!     type Pointer = Arc<MyStruct>;//!//!     fn run(this: Arc<MyStruct>) {//!         pr_info!("The value is: {}\n", this.value);//!     }//! }//!//! /// This method will enqueue the struct for execution on the system workqueue, where its value//! /// will be printed.//! fn print_later(val: Arc<MyStruct>) {//!     let _ = workqueue::system().enqueue(val);//! }//! # print_later(MyStruct::new(42).unwrap());//! ```//!//! The following example shows how multiple `work_struct` fields can be used://!//! ```//! use kernel::sync::Arc;//! use kernel::workqueue::{self, impl_has_work, new_work, Work, WorkItem};//!//! #[pin_data]//! struct MyStruct {//!     value_1: i32,//!     value_2: i32,//!     #[pin]//!     work_1: Work<MyStruct, 1>,//!     #[pin]//!     work_2: Work<MyStruct, 2>,//! }//!//! impl_has_work! {//!     impl HasWork<Self, 1> for MyStruct { self.work_1 }//!     impl HasWork<Self, 2> for MyStruct { self.work_2 }//! }//!//! impl MyStruct {//!     fn new(value_1: i32, value_2: i32) -> Result<Arc<Self>> {//!         Arc::pin_init(pin_init!(MyStruct {//!             value_1,//!             value_2,//!             work_1 <- new_work!("MyStruct::work_1"),//!             work_2 <- new_work!("MyStruct::work_2"),//!         }), GFP_KERNEL)//!     }//! }//!//! impl WorkItem<1> for MyStruct {//!     type Pointer = Arc<MyStruct>;//!//!     fn run(this: Arc<MyStruct>) {//!         pr_info!("The value is: {}\n", this.value_1);//!     }//! }//!//! impl WorkItem<2> for MyStruct {//!     type Pointer = Arc<MyStruct>;//!//!     fn run(this: Arc<MyStruct>) {//!         pr_info!("The second value is: {}\n", this.value_2);//!     }//! }//!//! fn print_1_later(val: Arc<MyStruct>) {//!     let _ = workqueue::system().enqueue::<Arc<MyStruct>, 1>(val);//! }//!//! fn print_2_later(val: Arc<MyStruct>) {//!     let _ = workqueue::system().enqueue::<Arc<MyStruct>, 2>(val);//! }//! # print_1_later(MyStruct::new(24, 25).unwrap());//! # print_2_later(MyStruct::new(41, 42).unwrap());//! ```//!//! C header: [`include/linux/workqueue.h`](srctree/include/linux/workqueue.h) use crate::alloc::{AllocError, Flags};use crate::{prelude::*, sync::Arc, sync::LockClassKey, types::Opaque};use core::marker::PhantomData; /// Creates a [`Work`] initialiser with the given name and a newly-created lock class.#[macro_export]macro_rules! new_work {    ($($name:literal)?) => {        $crate::workqueue::Work::new($crate::optional_name!($($name)?), $crate::static_lock_class!())    };}pub use new_work; /// A kernel work queue.////// Wraps the kernel's C `struct workqueue_struct`.////// It allows work items to be queued to run on thread pools managed by the kernel. Several are/// always available, for example, `system`, `system_highpri`, `system_long`, etc.#[repr(transparent)]pub struct Queue(Opaque<bindings::workqueue_struct>); // SAFETY: Accesses to workqueues used by [`Queue`] are thread-safe.unsafe impl Send for Queue {}// SAFETY: Accesses to workqueues used by [`Queue`] are thread-safe.unsafe impl Sync for Queue {} impl Queue {    /// Use the provided `struct workqueue_struct` with Rust.    ///    /// # Safety    ///    /// The caller must ensure that the provided raw pointer is not dangling, that it points at a    /// valid workqueue, and that it remains valid until the end of `'a`.    pub unsafe fn from_raw<'a>(ptr: *const bindings::workqueue_struct) -> &'a Queue {        // SAFETY: The `Queue` type is `#[repr(transparent)]`, so the pointer cast is valid. The        // caller promises that the pointer is not dangling.        unsafe { &*(ptr as *const Queue) }    }     /// Enqueues a work item.    ///    /// This may fail if the work item is already enqueued in a workqueue.    ///    /// The work item will be submitted using `WORK_CPU_UNBOUND`.    pub fn enqueue<W, const ID: u64>(&self, w: W) -> W::EnqueueOutput    where        W: RawWorkItem<ID> + Send + 'static,    {        let queue_ptr = self.0.get();         // SAFETY: We only return `false` if the `work_struct` is already in a workqueue. The other        // `__enqueue` requirements are not relevant since `W` is `Send` and static.        //        // The call to `bindings::queue_work_on` will dereference the provided raw pointer, which        // is ok because `__enqueue` guarantees that the pointer is valid for the duration of this        // closure.        //        // Furthermore, if the C workqueue code accesses the pointer after this call to        // `__enqueue`, then the work item was successfully enqueued, and `bindings::queue_work_on`        // will have returned true. In this case, `__enqueue` promises that the raw pointer will        // stay valid until we call the function pointer in the `work_struct`, so the access is ok.        unsafe {            w.__enqueue(move |work_ptr| {                bindings::queue_work_on(                    bindings::wq_misc_consts_WORK_CPU_UNBOUND as _,                    queue_ptr,                    work_ptr,                )            })        }    }     /// Tries to spawn the given function or closure as a work item.    ///    /// This method can fail because it allocates memory to store the work item.    pub fn try_spawn<T: 'static + Send + FnOnce()>(        &self,        flags: Flags,        func: T,    ) -> Result<(), AllocError> {        let init = pin_init!(ClosureWork {            work <- new_work!("Queue::try_spawn"),            func: Some(func),        });         self.enqueue(KBox::pin_init(init, flags).map_err(|_| AllocError)?);        Ok(())    }} /// A helper type used in [`try_spawn`].////// [`try_spawn`]: Queue::try_spawn#[pin_data]struct ClosureWork<T> {    #[pin]    work: Work<ClosureWork<T>>,    func: Option<T>,} impl<T> ClosureWork<T> {    fn project(self: Pin<&mut Self>) -> &mut Option<T> {        // SAFETY: The `func` field is not structurally pinned.        unsafe { &mut self.get_unchecked_mut().func }    }} impl<T: FnOnce()> WorkItem for ClosureWork<T> {    type Pointer = Pin<KBox<Self>>;     fn run(mut this: Pin<KBox<Self>>) {        if let Some(func) = this.as_mut().project().take() {            (func)()        }    }} /// A raw work item.////// This is the low-level trait that is designed for being as general as possible.////// The `ID` parameter to this trait exists so that a single type can provide multiple/// implementations of this trait. For example, if a struct has multiple `work_struct` fields, then/// you will implement this trait once for each field, using a different id for each field. The/// actual value of the id is not important as long as you use different ids for different fields/// of the same struct. (Fields of different structs need not use different ids.)////// Note that the id is used only to select the right method to call during compilation. It won't be/// part of the final executable.////// # Safety////// Implementers must ensure that any pointers passed to a `queue_work_on` closure by [`__enqueue`]/// remain valid for the duration specified in the guarantees section of the documentation for/// [`__enqueue`].////// [`__enqueue`]: RawWorkItem::__enqueuepub unsafe trait RawWorkItem<const ID: u64> {    /// The return type of [`Queue::enqueue`].    type EnqueueOutput;     /// Enqueues this work item on a queue using the provided `queue_work_on` method.    ///    /// # Guarantees    ///    /// If this method calls the provided closure, then the raw pointer is guaranteed to point at a    /// valid `work_struct` for the duration of the call to the closure. If the closure returns    /// true, then it is further guaranteed that the pointer remains valid until someone calls the    /// function pointer stored in the `work_struct`.    ///    /// # Safety    ///    /// The provided closure may only return `false` if the `work_struct` is already in a workqueue.    ///    /// If the work item type is annotated with any lifetimes, then you must not call the function    /// pointer after any such lifetime expires. (Never calling the function pointer is okay.)    ///    /// If the work item type is not [`Send`], then the function pointer must be called on the same    /// thread as the call to `__enqueue`.    unsafe fn __enqueue<F>(self, queue_work_on: F) -> Self::EnqueueOutput    where        F: FnOnce(*mut bindings::work_struct) -> bool;} /// Defines the method that should be called directly when a work item is executed.////// This trait is implemented by `Pin<KBox<T>>` and [`Arc<T>`], and is mainly intended to be/// implemented for smart pointer types. For your own structs, you would implement [`WorkItem`]/// instead. The [`run`] method on this trait will usually just perform the appropriate/// `container_of` translation and then call into the [`run`][WorkItem::run] method from the/// [`WorkItem`] trait.////// This trait is used when the `work_struct` field is defined using the [`Work`] helper.////// # Safety////// Implementers must ensure that [`__enqueue`] uses a `work_struct` initialized with the [`run`]/// method of this trait as the function pointer.////// [`__enqueue`]: RawWorkItem::__enqueue/// [`run`]: WorkItemPointer::runpub unsafe trait WorkItemPointer<const ID: u64>: RawWorkItem<ID> {    /// Run this work item.    ///    /// # Safety    ///    /// The provided `work_struct` pointer must originate from a previous call to [`__enqueue`]    /// where the `queue_work_on` closure returned true, and the pointer must still be valid.    ///    /// [`__enqueue`]: RawWorkItem::__enqueue    unsafe extern "C" fn run(ptr: *mut bindings::work_struct);} /// Defines the method that should be called when this work item is executed.////// This trait is used when the `work_struct` field is defined using the [`Work`] helper.pub trait WorkItem<const ID: u64 = 0> {    /// The pointer type that this struct is wrapped in. This will typically be `Arc<Self>` or    /// `Pin<KBox<Self>>`.    type Pointer: WorkItemPointer<ID>;     /// The method that should be called when this work item is executed.    fn run(this: Self::Pointer);} /// Links for a work item.////// This struct contains a function pointer to the [`run`] function from the [`WorkItemPointer`]/// trait, and defines the linked list pointers necessary to enqueue a work item in a workqueue.////// Wraps the kernel's C `struct work_struct`.////// This is a helper type used to associate a `work_struct` with the [`WorkItem`] that uses it.////// [`run`]: WorkItemPointer::run#[pin_data]#[repr(transparent)]pub struct Work<T: ?Sized, const ID: u64 = 0> {    #[pin]    work: Opaque<bindings::work_struct>,    _inner: PhantomData<T>,} // SAFETY: Kernel work items are usable from any thread.//// We do not need to constrain `T` since the work item does not actually contain a `T`.unsafe impl<T: ?Sized, const ID: u64> Send for Work<T, ID> {}// SAFETY: Kernel work items are usable from any thread.//// We do not need to constrain `T` since the work item does not actually contain a `T`.unsafe impl<T: ?Sized, const ID: u64> Sync for Work<T, ID> {} impl<T: ?Sized, const ID: u64> Work<T, ID> {    /// Creates a new instance of [`Work`].    #[inline]    pub fn new(name: &'static CStr, key: &'static LockClassKey) -> impl PinInit<Self>    where        T: WorkItem<ID>,    {        pin_init!(Self {            work <- Opaque::ffi_init(|slot| {                // SAFETY: The `WorkItemPointer` implementation promises that `run` can be used as                // the work item function.                unsafe {                    bindings::init_work_with_key(                        slot,                        Some(T::Pointer::run),                        false,                        name.as_char_ptr(),                        key.as_ptr(),                    )                }            }),            _inner: PhantomData,        })    }     /// Get a pointer to the inner `work_struct`.    ///    /// # Safety    ///    /// The provided pointer must not be dangling and must be properly aligned. (But the memory    /// need not be initialized.)    #[inline]    pub unsafe fn raw_get(ptr: *const Self) -> *mut bindings::work_struct {        // SAFETY: The caller promises that the pointer is aligned and not dangling.        //        // A pointer cast would also be ok due to `#[repr(transparent)]`. We use `addr_of!` so that        // the compiler does not complain that the `work` field is unused.        unsafe { Opaque::raw_get(core::ptr::addr_of!((*ptr).work)) }    }} /// Declares that a type has a [`Work<T, ID>`] field.////// The intended way of using this trait is via the [`impl_has_work!`] macro. You can use the macro/// like this:////// ```no_run/// use kernel::workqueue::{impl_has_work, Work};////// struct MyWorkItem {///     work_field: Work<MyWorkItem, 1>,/// }////// impl_has_work! {///     impl HasWork<MyWorkItem, 1> for MyWorkItem { self.work_field }/// }/// ```////// Note that since the [`Work`] type is annotated with an id, you can have several `work_struct`/// fields by using a different id for each one.////// # Safety////// The [`OFFSET`] constant must be the offset of a field in `Self` of type [`Work<T, ID>`]. The/// methods on this trait must have exactly the behavior that the definitions given below have.////// [`impl_has_work!`]: crate::impl_has_work/// [`OFFSET`]: HasWork::OFFSETpub unsafe trait HasWork<T, const ID: u64 = 0> {    /// The offset of the [`Work<T, ID>`] field.    const OFFSET: usize;     /// Returns the offset of the [`Work<T, ID>`] field.    ///    /// This method exists because the [`OFFSET`] constant cannot be accessed if the type is not    /// [`Sized`].    ///    /// [`OFFSET`]: HasWork::OFFSET    #[inline]    fn get_work_offset(&self) -> usize {        Self::OFFSET    }     /// Returns a pointer to the [`Work<T, ID>`] field.    ///    /// # Safety    ///    /// The provided pointer must point at a valid struct of type `Self`.    #[inline]    unsafe fn raw_get_work(ptr: *mut Self) -> *mut Work<T, ID> {        // SAFETY: The caller promises that the pointer is valid.        unsafe { (ptr as *mut u8).add(Self::OFFSET) as *mut Work<T, ID> }    }     /// Returns a pointer to the struct containing the [`Work<T, ID>`] field.    ///    /// # Safety    ///    /// The pointer must point at a [`Work<T, ID>`] field in a struct of type `Self`.    #[inline]    unsafe fn work_container_of(ptr: *mut Work<T, ID>) -> *mut Self    where        Self: Sized,    {        // SAFETY: The caller promises that the pointer points at a field of the right type in the        // right kind of struct.        unsafe { (ptr as *mut u8).sub(Self::OFFSET) as *mut Self }    }} /// Used to safely implement the [`HasWork<T, ID>`] trait.////// # Examples////// ```/// use kernel::sync::Arc;/// use kernel::workqueue::{self, impl_has_work, Work};////// struct MyStruct<'a, T, const N: usize> {///     work_field: Work<MyStruct<'a, T, N>, 17>,///     f: fn(&'a [T; N]),/// }////// impl_has_work! {///     impl{'a, T, const N: usize} HasWork<MyStruct<'a, T, N>, 17>///     for MyStruct<'a, T, N> { self.work_field }/// }/// ```#[macro_export]macro_rules! impl_has_work {    ($(impl$({$($generics:tt)*})?       HasWork<$work_type:ty $(, $id:tt)?>

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