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This patch is being sent for use in the various Rust GPU drivers that are under development. It provides the additional feature of work items that are executed after a delay. The design of the existing workqueue is rather extensible, as most of the logic is reused for delayed work items even though a different work item type is required. The new logic consists of: * A new DelayedWork struct that wraps struct delayed_work. * A new impl_has_delayed_work! macro that provides adjusted versions of the container_of logic, that is suitable with delayed work items. * A `enqueue_delayed` method that can enqueue a delayed work item. This patch does *not* rely on the fact that `struct delayed_work` contains `struct work_struct` at offset zero. It will continue to work even if the layout is changed to hold the `work` field at a different offset. Please see the example introduced at the top of the file for example usage of delayed work items. Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Alice Ryhl <aliceryhl@google.com> Link: https://lore.kernel.org/r/20250711-workqueue-delay-v3-1-3fe17b18b9d1@google.com [ Replaced `as _` with `as ffi::c_int` to clean warning. - Miguel ] Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
1031 lines
39 KiB
Rust
1031 lines
39 KiB
Rust
// SPDX-License-Identifier: GPL-2.0
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//! Work queues.
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//!
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//! This file has two components: The raw work item API, and the safe work item API.
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//!
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//! One pattern that is used in both APIs is the `ID` const generic, which exists to allow a single
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//! type to define multiple `work_struct` fields. This is done by choosing an id for each field,
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//! and using that id to specify which field you wish to use. (The actual value doesn't matter, as
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//! long as you use different values for different fields of the same struct.) Since these IDs are
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//! generic, they are used only at compile-time, so they shouldn't exist in the final binary.
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//!
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//! # The raw API
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//!
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//! The raw API consists of the [`RawWorkItem`] trait, where the work item needs to provide an
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//! arbitrary function that knows how to enqueue the work item. It should usually not be used
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//! directly, but if you want to, you can use it without using the pieces from the safe API.
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//!
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//! # The safe API
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//!
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//! The safe API is used via the [`Work`] struct and [`WorkItem`] traits. Furthermore, it also
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//! includes a trait called [`WorkItemPointer`], which is usually not used directly by the user.
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//!
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//! * The [`Work`] struct is the Rust wrapper for the C `work_struct` type.
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//! * The [`WorkItem`] trait is implemented for structs that can be enqueued to a workqueue.
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//! * The [`WorkItemPointer`] trait is implemented for the pointer type that points at a something
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//! that implements [`WorkItem`].
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//!
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//! ## Examples
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//!
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//! This example defines a struct that holds an integer and can be scheduled on the workqueue. When
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//! the struct is executed, it will print the integer. Since there is only one `work_struct` field,
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//! we do not need to specify ids for the fields.
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//!
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//! ```
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//! use kernel::sync::Arc;
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//! use kernel::workqueue::{self, impl_has_work, new_work, Work, WorkItem};
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//!
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//! #[pin_data]
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//! struct MyStruct {
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//! value: i32,
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//! #[pin]
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//! work: Work<MyStruct>,
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//! }
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//!
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//! impl_has_work! {
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//! impl HasWork<Self> for MyStruct { self.work }
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//! }
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//!
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//! impl MyStruct {
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//! fn new(value: i32) -> Result<Arc<Self>> {
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//! Arc::pin_init(pin_init!(MyStruct {
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//! value,
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//! work <- new_work!("MyStruct::work"),
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//! }), GFP_KERNEL)
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//! }
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//! }
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//!
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//! impl WorkItem for MyStruct {
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//! type Pointer = Arc<MyStruct>;
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//!
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//! fn run(this: Arc<MyStruct>) {
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//! pr_info!("The value is: {}\n", this.value);
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//! }
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//! }
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//!
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//! /// This method will enqueue the struct for execution on the system workqueue, where its value
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//! /// will be printed.
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//! fn print_later(val: Arc<MyStruct>) {
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//! let _ = workqueue::system().enqueue(val);
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//! }
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//! # print_later(MyStruct::new(42).unwrap());
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//! ```
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//!
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//! The following example shows how multiple `work_struct` fields can be used:
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//!
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//! ```
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//! use kernel::sync::Arc;
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//! use kernel::workqueue::{self, impl_has_work, new_work, Work, WorkItem};
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//!
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//! #[pin_data]
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//! struct MyStruct {
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//! value_1: i32,
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//! value_2: i32,
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//! #[pin]
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//! work_1: Work<MyStruct, 1>,
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//! #[pin]
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//! work_2: Work<MyStruct, 2>,
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//! }
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//!
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//! impl_has_work! {
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//! impl HasWork<Self, 1> for MyStruct { self.work_1 }
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//! impl HasWork<Self, 2> for MyStruct { self.work_2 }
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//! }
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//!
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//! impl MyStruct {
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//! fn new(value_1: i32, value_2: i32) -> Result<Arc<Self>> {
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//! Arc::pin_init(pin_init!(MyStruct {
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//! value_1,
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//! value_2,
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//! work_1 <- new_work!("MyStruct::work_1"),
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//! work_2 <- new_work!("MyStruct::work_2"),
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//! }), GFP_KERNEL)
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//! }
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//! }
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//!
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//! impl WorkItem<1> for MyStruct {
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//! type Pointer = Arc<MyStruct>;
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//!
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//! fn run(this: Arc<MyStruct>) {
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//! pr_info!("The value is: {}\n", this.value_1);
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//! }
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//! }
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//!
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//! impl WorkItem<2> for MyStruct {
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//! type Pointer = Arc<MyStruct>;
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//!
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//! fn run(this: Arc<MyStruct>) {
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//! pr_info!("The second value is: {}\n", this.value_2);
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//! }
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//! }
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//!
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//! fn print_1_later(val: Arc<MyStruct>) {
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//! let _ = workqueue::system().enqueue::<Arc<MyStruct>, 1>(val);
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//! }
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//!
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//! fn print_2_later(val: Arc<MyStruct>) {
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//! let _ = workqueue::system().enqueue::<Arc<MyStruct>, 2>(val);
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//! }
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//! # print_1_later(MyStruct::new(24, 25).unwrap());
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//! # print_2_later(MyStruct::new(41, 42).unwrap());
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//! ```
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//!
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//! This example shows how you can schedule delayed work items:
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//!
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//! ```
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//! use kernel::sync::Arc;
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//! use kernel::workqueue::{self, impl_has_delayed_work, new_delayed_work, DelayedWork, WorkItem};
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//!
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//! #[pin_data]
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//! struct MyStruct {
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//! value: i32,
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//! #[pin]
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//! work: DelayedWork<MyStruct>,
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//! }
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//!
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//! impl_has_delayed_work! {
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//! impl HasDelayedWork<Self> for MyStruct { self.work }
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//! }
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//!
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//! impl MyStruct {
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//! fn new(value: i32) -> Result<Arc<Self>> {
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//! Arc::pin_init(
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//! pin_init!(MyStruct {
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//! value,
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//! work <- new_delayed_work!("MyStruct::work"),
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//! }),
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//! GFP_KERNEL,
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//! )
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//! }
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//! }
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//!
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//! impl WorkItem for MyStruct {
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//! type Pointer = Arc<MyStruct>;
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//!
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//! fn run(this: Arc<MyStruct>) {
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//! pr_info!("The value is: {}\n", this.value);
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//! }
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//! }
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//!
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//! /// This method will enqueue the struct for execution on the system workqueue, where its value
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//! /// will be printed 12 jiffies later.
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//! fn print_later(val: Arc<MyStruct>) {
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//! let _ = workqueue::system().enqueue_delayed(val, 12);
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//! }
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//!
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//! /// It is also possible to use the ordinary `enqueue` method together with `DelayedWork`. This
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//! /// is equivalent to calling `enqueue_delayed` with a delay of zero.
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//! fn print_now(val: Arc<MyStruct>) {
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//! let _ = workqueue::system().enqueue(val);
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//! }
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//! # print_later(MyStruct::new(42).unwrap());
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//! # print_now(MyStruct::new(42).unwrap());
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//! ```
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//!
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//! C header: [`include/linux/workqueue.h`](srctree/include/linux/workqueue.h)
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use crate::{
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alloc::{AllocError, Flags},
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container_of,
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prelude::*,
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sync::Arc,
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sync::LockClassKey,
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time::Jiffies,
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types::Opaque,
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};
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use core::marker::PhantomData;
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/// Creates a [`Work`] initialiser with the given name and a newly-created lock class.
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#[macro_export]
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macro_rules! new_work {
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($($name:literal)?) => {
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$crate::workqueue::Work::new($crate::optional_name!($($name)?), $crate::static_lock_class!())
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};
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}
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pub use new_work;
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/// Creates a [`DelayedWork`] initialiser with the given name and a newly-created lock class.
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#[macro_export]
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macro_rules! new_delayed_work {
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() => {
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$crate::workqueue::DelayedWork::new(
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$crate::optional_name!(),
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$crate::static_lock_class!(),
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$crate::c_str!(::core::concat!(
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::core::file!(),
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":",
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::core::line!(),
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"_timer"
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)),
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$crate::static_lock_class!(),
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)
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};
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($name:literal) => {
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$crate::workqueue::DelayedWork::new(
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$crate::c_str!($name),
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$crate::static_lock_class!(),
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$crate::c_str!(::core::concat!($name, "_timer")),
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$crate::static_lock_class!(),
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)
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};
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}
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pub use new_delayed_work;
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/// A kernel work queue.
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///
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/// Wraps the kernel's C `struct workqueue_struct`.
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///
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/// It allows work items to be queued to run on thread pools managed by the kernel. Several are
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/// always available, for example, `system`, `system_highpri`, `system_long`, etc.
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#[repr(transparent)]
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pub struct Queue(Opaque<bindings::workqueue_struct>);
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// SAFETY: Accesses to workqueues used by [`Queue`] are thread-safe.
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unsafe impl Send for Queue {}
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// SAFETY: Accesses to workqueues used by [`Queue`] are thread-safe.
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unsafe impl Sync for Queue {}
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impl Queue {
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/// Use the provided `struct workqueue_struct` with Rust.
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///
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/// # Safety
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///
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/// The caller must ensure that the provided raw pointer is not dangling, that it points at a
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/// valid workqueue, and that it remains valid until the end of `'a`.
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pub unsafe fn from_raw<'a>(ptr: *const bindings::workqueue_struct) -> &'a Queue {
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// SAFETY: The `Queue` type is `#[repr(transparent)]`, so the pointer cast is valid. The
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// caller promises that the pointer is not dangling.
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unsafe { &*ptr.cast::<Queue>() }
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}
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/// Enqueues a work item.
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///
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/// This may fail if the work item is already enqueued in a workqueue.
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///
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/// The work item will be submitted using `WORK_CPU_UNBOUND`.
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pub fn enqueue<W, const ID: u64>(&self, w: W) -> W::EnqueueOutput
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where
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W: RawWorkItem<ID> + Send + 'static,
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{
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let queue_ptr = self.0.get();
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// SAFETY: We only return `false` if the `work_struct` is already in a workqueue. The other
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// `__enqueue` requirements are not relevant since `W` is `Send` and static.
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//
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// The call to `bindings::queue_work_on` will dereference the provided raw pointer, which
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// is ok because `__enqueue` guarantees that the pointer is valid for the duration of this
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// closure.
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//
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// Furthermore, if the C workqueue code accesses the pointer after this call to
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// `__enqueue`, then the work item was successfully enqueued, and `bindings::queue_work_on`
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// will have returned true. In this case, `__enqueue` promises that the raw pointer will
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// stay valid until we call the function pointer in the `work_struct`, so the access is ok.
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unsafe {
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w.__enqueue(move |work_ptr| {
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bindings::queue_work_on(
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bindings::wq_misc_consts_WORK_CPU_UNBOUND as ffi::c_int,
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queue_ptr,
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work_ptr,
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)
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})
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}
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}
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/// Enqueues a delayed work item.
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///
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/// This may fail if the work item is already enqueued in a workqueue.
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///
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/// The work item will be submitted using `WORK_CPU_UNBOUND`.
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pub fn enqueue_delayed<W, const ID: u64>(&self, w: W, delay: Jiffies) -> W::EnqueueOutput
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where
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W: RawDelayedWorkItem<ID> + Send + 'static,
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{
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let queue_ptr = self.0.get();
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// SAFETY: We only return `false` if the `work_struct` is already in a workqueue. The other
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// `__enqueue` requirements are not relevant since `W` is `Send` and static.
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//
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// The call to `bindings::queue_delayed_work_on` will dereference the provided raw pointer,
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// which is ok because `__enqueue` guarantees that the pointer is valid for the duration of
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// this closure, and the safety requirements of `RawDelayedWorkItem` expands this
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// requirement to apply to the entire `delayed_work`.
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//
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// Furthermore, if the C workqueue code accesses the pointer after this call to
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// `__enqueue`, then the work item was successfully enqueued, and
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// `bindings::queue_delayed_work_on` will have returned true. In this case, `__enqueue`
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// promises that the raw pointer will stay valid until we call the function pointer in the
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// `work_struct`, so the access is ok.
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unsafe {
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w.__enqueue(move |work_ptr| {
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bindings::queue_delayed_work_on(
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bindings::wq_misc_consts_WORK_CPU_UNBOUND as ffi::c_int,
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queue_ptr,
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container_of!(work_ptr, bindings::delayed_work, work),
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delay,
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)
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})
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}
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}
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/// Tries to spawn the given function or closure as a work item.
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///
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/// This method can fail because it allocates memory to store the work item.
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pub fn try_spawn<T: 'static + Send + FnOnce()>(
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&self,
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flags: Flags,
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func: T,
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) -> Result<(), AllocError> {
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let init = pin_init!(ClosureWork {
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work <- new_work!("Queue::try_spawn"),
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func: Some(func),
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});
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self.enqueue(KBox::pin_init(init, flags).map_err(|_| AllocError)?);
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Ok(())
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}
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}
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/// A helper type used in [`try_spawn`].
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///
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/// [`try_spawn`]: Queue::try_spawn
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#[pin_data]
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struct ClosureWork<T> {
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#[pin]
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work: Work<ClosureWork<T>>,
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func: Option<T>,
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}
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impl<T> ClosureWork<T> {
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fn project(self: Pin<&mut Self>) -> &mut Option<T> {
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// SAFETY: The `func` field is not structurally pinned.
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unsafe { &mut self.get_unchecked_mut().func }
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}
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}
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impl<T: FnOnce()> WorkItem for ClosureWork<T> {
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type Pointer = Pin<KBox<Self>>;
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fn run(mut this: Pin<KBox<Self>>) {
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if let Some(func) = this.as_mut().project().take() {
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(func)()
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}
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}
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}
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/// A raw work item.
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///
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/// This is the low-level trait that is designed for being as general as possible.
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///
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/// The `ID` parameter to this trait exists so that a single type can provide multiple
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/// implementations of this trait. For example, if a struct has multiple `work_struct` fields, then
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/// you will implement this trait once for each field, using a different id for each field. The
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/// actual value of the id is not important as long as you use different ids for different fields
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/// of the same struct. (Fields of different structs need not use different ids.)
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///
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/// Note that the id is used only to select the right method to call during compilation. It won't be
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/// part of the final executable.
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///
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/// # Safety
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///
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/// Implementers must ensure that any pointers passed to a `queue_work_on` closure by [`__enqueue`]
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/// remain valid for the duration specified in the guarantees section of the documentation for
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/// [`__enqueue`].
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///
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/// [`__enqueue`]: RawWorkItem::__enqueue
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pub unsafe trait RawWorkItem<const ID: u64> {
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/// The return type of [`Queue::enqueue`].
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type EnqueueOutput;
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/// Enqueues this work item on a queue using the provided `queue_work_on` method.
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///
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/// # Guarantees
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///
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/// If this method calls the provided closure, then the raw pointer is guaranteed to point at a
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/// valid `work_struct` for the duration of the call to the closure. If the closure returns
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/// true, then it is further guaranteed that the pointer remains valid until someone calls the
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/// function pointer stored in the `work_struct`.
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///
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/// # Safety
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///
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/// The provided closure may only return `false` if the `work_struct` is already in a workqueue.
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///
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/// If the work item type is annotated with any lifetimes, then you must not call the function
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/// pointer after any such lifetime expires. (Never calling the function pointer is okay.)
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///
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/// If the work item type is not [`Send`], then the function pointer must be called on the same
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/// thread as the call to `__enqueue`.
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unsafe fn __enqueue<F>(self, queue_work_on: F) -> Self::EnqueueOutput
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where
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F: FnOnce(*mut bindings::work_struct) -> bool;
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}
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/// A raw delayed work item.
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///
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/// # Safety
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///
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/// If the `__enqueue` method in the `RawWorkItem` implementation calls the closure, then the
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/// provided pointer must point at the `work` field of a valid `delayed_work`, and the guarantees
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/// that `__enqueue` provides about accessing the `work_struct` must also apply to the rest of the
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/// `delayed_work` struct.
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pub unsafe trait RawDelayedWorkItem<const ID: u64>: RawWorkItem<ID> {}
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/// Defines the method that should be called directly when a work item is executed.
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///
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/// This trait is implemented by `Pin<KBox<T>>` and [`Arc<T>`], and is mainly intended to be
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/// implemented for smart pointer types. For your own structs, you would implement [`WorkItem`]
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/// instead. The [`run`] method on this trait will usually just perform the appropriate
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/// `container_of` translation and then call into the [`run`][WorkItem::run] method from the
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/// [`WorkItem`] trait.
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///
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/// This trait is used when the `work_struct` field is defined using the [`Work`] helper.
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///
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/// # Safety
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///
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/// Implementers must ensure that [`__enqueue`] uses a `work_struct` initialized with the [`run`]
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/// method of this trait as the function pointer.
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///
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/// [`__enqueue`]: RawWorkItem::__enqueue
|
|
/// [`run`]: WorkItemPointer::run
|
|
pub 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: Pin<&'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::cast_into(core::ptr::addr_of!((*ptr).work)) }
|
|
}
|
|
}
|
|
|
|
/// Declares that a type contains a [`Work<T, ID>`].
|
|
///
|
|
/// 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 methods [`raw_get_work`] and [`work_container_of`] must return valid pointers and must be
|
|
/// true inverses of each other; that is, they must satisfy the following invariants:
|
|
/// - `work_container_of(raw_get_work(ptr)) == ptr` for any `ptr: *mut Self`.
|
|
/// - `raw_get_work(work_container_of(ptr)) == ptr` for any `ptr: *mut Work<T, ID>`.
|
|
///
|
|
/// [`impl_has_work!`]: crate::impl_has_work
|
|
/// [`raw_get_work`]: HasWork::raw_get_work
|
|
/// [`work_container_of`]: HasWork::work_container_of
|
|
pub unsafe trait HasWork<T, const ID: u64 = 0> {
|
|
/// Returns a pointer to the [`Work<T, ID>`] field.
|
|
///
|
|
/// # Safety
|
|
///
|
|
/// The provided pointer must point at a valid struct of type `Self`.
|
|
unsafe fn raw_get_work(ptr: *mut Self) -> *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`.
|
|
unsafe fn work_container_of(ptr: *mut Work<T, ID>) -> *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)?>
|
|
for $self:ty
|
|
{ self.$field:ident }
|
|
)*) => {$(
|
|
// SAFETY: The implementation of `raw_get_work` only compiles if the field has the right
|
|
// type.
|
|
unsafe impl$(<$($generics)+>)? $crate::workqueue::HasWork<$work_type $(, $id)?> for $self {
|
|
#[inline]
|
|
unsafe fn raw_get_work(ptr: *mut Self) -> *mut $crate::workqueue::Work<$work_type $(, $id)?> {
|
|
// SAFETY: The caller promises that the pointer is not dangling.
|
|
unsafe {
|
|
::core::ptr::addr_of_mut!((*ptr).$field)
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
unsafe fn work_container_of(
|
|
ptr: *mut $crate::workqueue::Work<$work_type $(, $id)?>,
|
|
) -> *mut Self {
|
|
// SAFETY: The caller promises that the pointer points at a field of the right type
|
|
// in the right kind of struct.
|
|
unsafe { $crate::container_of!(ptr, Self, $field) }
|
|
}
|
|
}
|
|
)*};
|
|
}
|
|
pub use impl_has_work;
|
|
|
|
impl_has_work! {
|
|
impl{T} HasWork<Self> for ClosureWork<T> { self.work }
|
|
}
|
|
|
|
/// Links for a delayed 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 in
|
|
/// a delayed manner.
|
|
///
|
|
/// Wraps the kernel's C `struct delayed_work`.
|
|
///
|
|
/// This is a helper type used to associate a `delayed_work` with the [`WorkItem`] that uses it.
|
|
///
|
|
/// [`run`]: WorkItemPointer::run
|
|
#[pin_data]
|
|
#[repr(transparent)]
|
|
pub struct DelayedWork<T: ?Sized, const ID: u64 = 0> {
|
|
#[pin]
|
|
dwork: Opaque<bindings::delayed_work>,
|
|
_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 DelayedWork<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 DelayedWork<T, ID> {}
|
|
|
|
impl<T: ?Sized, const ID: u64> DelayedWork<T, ID> {
|
|
/// Creates a new instance of [`DelayedWork`].
|
|
#[inline]
|
|
pub fn new(
|
|
work_name: &'static CStr,
|
|
work_key: Pin<&'static LockClassKey>,
|
|
timer_name: &'static CStr,
|
|
timer_key: Pin<&'static LockClassKey>,
|
|
) -> impl PinInit<Self>
|
|
where
|
|
T: WorkItem<ID>,
|
|
{
|
|
pin_init!(Self {
|
|
dwork <- Opaque::ffi_init(|slot: *mut bindings::delayed_work| {
|
|
// SAFETY: The `WorkItemPointer` implementation promises that `run` can be used as
|
|
// the work item function.
|
|
unsafe {
|
|
bindings::init_work_with_key(
|
|
core::ptr::addr_of_mut!((*slot).work),
|
|
Some(T::Pointer::run),
|
|
false,
|
|
work_name.as_char_ptr(),
|
|
work_key.as_ptr(),
|
|
)
|
|
}
|
|
|
|
// SAFETY: The `delayed_work_timer_fn` function pointer can be used here because
|
|
// the timer is embedded in a `struct delayed_work`, and only ever scheduled via
|
|
// the core workqueue code, and configured to run in irqsafe context.
|
|
unsafe {
|
|
bindings::timer_init_key(
|
|
core::ptr::addr_of_mut!((*slot).timer),
|
|
Some(bindings::delayed_work_timer_fn),
|
|
bindings::TIMER_IRQSAFE,
|
|
timer_name.as_char_ptr(),
|
|
timer_key.as_ptr(),
|
|
)
|
|
}
|
|
}),
|
|
_inner: PhantomData,
|
|
})
|
|
}
|
|
|
|
/// Get a pointer to the inner `delayed_work`.
|
|
///
|
|
/// # 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_as_work(ptr: *const Self) -> *mut Work<T, ID> {
|
|
// SAFETY: The caller promises that the pointer is aligned and not dangling.
|
|
let dw: *mut bindings::delayed_work =
|
|
unsafe { Opaque::cast_into(core::ptr::addr_of!((*ptr).dwork)) };
|
|
// SAFETY: The caller promises that the pointer is aligned and not dangling.
|
|
let wrk: *mut bindings::work_struct = unsafe { core::ptr::addr_of_mut!((*dw).work) };
|
|
// CAST: Work and work_struct have compatible layouts.
|
|
wrk.cast()
|
|
}
|
|
}
|
|
|
|
/// Declares that a type contains a [`DelayedWork<T, ID>`].
|
|
///
|
|
/// # Safety
|
|
///
|
|
/// The `HasWork<T, ID>` implementation must return a `work_struct` that is stored in the `work`
|
|
/// field of a `delayed_work` with the same access rules as the `work_struct`.
|
|
pub unsafe trait HasDelayedWork<T, const ID: u64 = 0>: HasWork<T, ID> {}
|
|
|
|
/// Used to safely implement the [`HasDelayedWork<T, ID>`] trait.
|
|
///
|
|
/// This macro also implements the [`HasWork`] trait, so you do not need to use [`impl_has_work!`]
|
|
/// when using this macro.
|
|
///
|
|
/// # Examples
|
|
///
|
|
/// ```
|
|
/// use kernel::sync::Arc;
|
|
/// use kernel::workqueue::{self, impl_has_delayed_work, DelayedWork};
|
|
///
|
|
/// struct MyStruct<'a, T, const N: usize> {
|
|
/// work_field: DelayedWork<MyStruct<'a, T, N>, 17>,
|
|
/// f: fn(&'a [T; N]),
|
|
/// }
|
|
///
|
|
/// impl_has_delayed_work! {
|
|
/// impl{'a, T, const N: usize} HasDelayedWork<MyStruct<'a, T, N>, 17>
|
|
/// for MyStruct<'a, T, N> { self.work_field }
|
|
/// }
|
|
/// ```
|
|
#[macro_export]
|
|
macro_rules! impl_has_delayed_work {
|
|
($(impl$({$($generics:tt)*})?
|
|
HasDelayedWork<$work_type:ty $(, $id:tt)?>
|
|
for $self:ty
|
|
{ self.$field:ident }
|
|
)*) => {$(
|
|
// SAFETY: The implementation of `raw_get_work` only compiles if the field has the right
|
|
// type.
|
|
unsafe impl$(<$($generics)+>)?
|
|
$crate::workqueue::HasDelayedWork<$work_type $(, $id)?> for $self {}
|
|
|
|
// SAFETY: The implementation of `raw_get_work` only compiles if the field has the right
|
|
// type.
|
|
unsafe impl$(<$($generics)+>)? $crate::workqueue::HasWork<$work_type $(, $id)?> for $self {
|
|
#[inline]
|
|
unsafe fn raw_get_work(
|
|
ptr: *mut Self
|
|
) -> *mut $crate::workqueue::Work<$work_type $(, $id)?> {
|
|
// SAFETY: The caller promises that the pointer is not dangling.
|
|
let ptr: *mut $crate::workqueue::DelayedWork<$work_type $(, $id)?> = unsafe {
|
|
::core::ptr::addr_of_mut!((*ptr).$field)
|
|
};
|
|
|
|
// SAFETY: The caller promises that the pointer is not dangling.
|
|
unsafe { $crate::workqueue::DelayedWork::raw_as_work(ptr) }
|
|
}
|
|
|
|
#[inline]
|
|
unsafe fn work_container_of(
|
|
ptr: *mut $crate::workqueue::Work<$work_type $(, $id)?>,
|
|
) -> *mut Self {
|
|
// SAFETY: The caller promises that the pointer points at a field of the right type
|
|
// in the right kind of struct.
|
|
let ptr = unsafe { $crate::workqueue::Work::raw_get(ptr) };
|
|
|
|
// SAFETY: The caller promises that the pointer points at a field of the right type
|
|
// in the right kind of struct.
|
|
let delayed_work = unsafe {
|
|
$crate::container_of!(ptr, $crate::bindings::delayed_work, work)
|
|
};
|
|
|
|
let delayed_work: *mut $crate::workqueue::DelayedWork<$work_type $(, $id)?> =
|
|
delayed_work.cast();
|
|
|
|
// SAFETY: The caller promises that the pointer points at a field of the right type
|
|
// in the right kind of struct.
|
|
unsafe { $crate::container_of!(delayed_work, Self, $field) }
|
|
}
|
|
}
|
|
)*};
|
|
}
|
|
pub use impl_has_delayed_work;
|
|
|
|
// SAFETY: The `__enqueue` implementation in RawWorkItem uses a `work_struct` initialized with the
|
|
// `run` method of this trait as the function pointer because:
|
|
// - `__enqueue` gets the `work_struct` from the `Work` field, using `T::raw_get_work`.
|
|
// - The only safe way to create a `Work` object is through `Work::new`.
|
|
// - `Work::new` makes sure that `T::Pointer::run` is passed to `init_work_with_key`.
|
|
// - Finally `Work` and `RawWorkItem` guarantee that the correct `Work` field
|
|
// will be used because of the ID const generic bound. This makes sure that `T::raw_get_work`
|
|
// uses the correct offset for the `Work` field, and `Work::new` picks the correct
|
|
// implementation of `WorkItemPointer` for `Arc<T>`.
|
|
unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Arc<T>
|
|
where
|
|
T: WorkItem<ID, Pointer = Self>,
|
|
T: HasWork<T, ID>,
|
|
{
|
|
unsafe extern "C" fn run(ptr: *mut bindings::work_struct) {
|
|
// The `__enqueue` method always uses a `work_struct` stored in a `Work<T, ID>`.
|
|
let ptr = ptr.cast::<Work<T, ID>>();
|
|
// SAFETY: This computes the pointer that `__enqueue` got from `Arc::into_raw`.
|
|
let ptr = unsafe { T::work_container_of(ptr) };
|
|
// SAFETY: This pointer comes from `Arc::into_raw` and we've been given back ownership.
|
|
let arc = unsafe { Arc::from_raw(ptr) };
|
|
|
|
T::run(arc)
|
|
}
|
|
}
|
|
|
|
// SAFETY: The `work_struct` raw pointer is guaranteed to be valid for the duration of the call to
|
|
// the closure because we get it from an `Arc`, which means that the ref count will be at least 1,
|
|
// and we don't drop the `Arc` ourselves. If `queue_work_on` returns true, it is further guaranteed
|
|
// to be valid until a call to the function pointer in `work_struct` because we leak the memory it
|
|
// points to, and only reclaim it if the closure returns false, or in `WorkItemPointer::run`, which
|
|
// is what the function pointer in the `work_struct` must be pointing to, according to the safety
|
|
// requirements of `WorkItemPointer`.
|
|
unsafe impl<T, const ID: u64> RawWorkItem<ID> for Arc<T>
|
|
where
|
|
T: WorkItem<ID, Pointer = Self>,
|
|
T: HasWork<T, ID>,
|
|
{
|
|
type EnqueueOutput = Result<(), Self>;
|
|
|
|
unsafe fn __enqueue<F>(self, queue_work_on: F) -> Self::EnqueueOutput
|
|
where
|
|
F: FnOnce(*mut bindings::work_struct) -> bool,
|
|
{
|
|
// Casting between const and mut is not a problem as long as the pointer is a raw pointer.
|
|
let ptr = Arc::into_raw(self).cast_mut();
|
|
|
|
// SAFETY: Pointers into an `Arc` point at a valid value.
|
|
let work_ptr = unsafe { T::raw_get_work(ptr) };
|
|
// SAFETY: `raw_get_work` returns a pointer to a valid value.
|
|
let work_ptr = unsafe { Work::raw_get(work_ptr) };
|
|
|
|
if queue_work_on(work_ptr) {
|
|
Ok(())
|
|
} else {
|
|
// SAFETY: The work queue has not taken ownership of the pointer.
|
|
Err(unsafe { Arc::from_raw(ptr) })
|
|
}
|
|
}
|
|
}
|
|
|
|
// SAFETY: By the safety requirements of `HasDelayedWork`, the `work_struct` returned by methods in
|
|
// `HasWork` provides a `work_struct` that is the `work` field of a `delayed_work`, and the rest of
|
|
// the `delayed_work` has the same access rules as its `work` field.
|
|
unsafe impl<T, const ID: u64> RawDelayedWorkItem<ID> for Arc<T>
|
|
where
|
|
T: WorkItem<ID, Pointer = Self>,
|
|
T: HasDelayedWork<T, ID>,
|
|
{
|
|
}
|
|
|
|
// SAFETY: TODO.
|
|
unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Pin<KBox<T>>
|
|
where
|
|
T: WorkItem<ID, Pointer = Self>,
|
|
T: HasWork<T, ID>,
|
|
{
|
|
unsafe extern "C" fn run(ptr: *mut bindings::work_struct) {
|
|
// The `__enqueue` method always uses a `work_struct` stored in a `Work<T, ID>`.
|
|
let ptr = ptr.cast::<Work<T, ID>>();
|
|
// SAFETY: This computes the pointer that `__enqueue` got from `Arc::into_raw`.
|
|
let ptr = unsafe { T::work_container_of(ptr) };
|
|
// SAFETY: This pointer comes from `Arc::into_raw` and we've been given back ownership.
|
|
let boxed = unsafe { KBox::from_raw(ptr) };
|
|
// SAFETY: The box was already pinned when it was enqueued.
|
|
let pinned = unsafe { Pin::new_unchecked(boxed) };
|
|
|
|
T::run(pinned)
|
|
}
|
|
}
|
|
|
|
// SAFETY: TODO.
|
|
unsafe impl<T, const ID: u64> RawWorkItem<ID> for Pin<KBox<T>>
|
|
where
|
|
T: WorkItem<ID, Pointer = Self>,
|
|
T: HasWork<T, ID>,
|
|
{
|
|
type EnqueueOutput = ();
|
|
|
|
unsafe fn __enqueue<F>(self, queue_work_on: F) -> Self::EnqueueOutput
|
|
where
|
|
F: FnOnce(*mut bindings::work_struct) -> bool,
|
|
{
|
|
// SAFETY: We're not going to move `self` or any of its fields, so its okay to temporarily
|
|
// remove the `Pin` wrapper.
|
|
let boxed = unsafe { Pin::into_inner_unchecked(self) };
|
|
let ptr = KBox::into_raw(boxed);
|
|
|
|
// SAFETY: Pointers into a `KBox` point at a valid value.
|
|
let work_ptr = unsafe { T::raw_get_work(ptr) };
|
|
// SAFETY: `raw_get_work` returns a pointer to a valid value.
|
|
let work_ptr = unsafe { Work::raw_get(work_ptr) };
|
|
|
|
if !queue_work_on(work_ptr) {
|
|
// SAFETY: This method requires exclusive ownership of the box, so it cannot be in a
|
|
// workqueue.
|
|
unsafe { ::core::hint::unreachable_unchecked() }
|
|
}
|
|
}
|
|
}
|
|
|
|
// SAFETY: By the safety requirements of `HasDelayedWork`, the `work_struct` returned by methods in
|
|
// `HasWork` provides a `work_struct` that is the `work` field of a `delayed_work`, and the rest of
|
|
// the `delayed_work` has the same access rules as its `work` field.
|
|
unsafe impl<T, const ID: u64> RawDelayedWorkItem<ID> for Pin<KBox<T>>
|
|
where
|
|
T: WorkItem<ID, Pointer = Self>,
|
|
T: HasDelayedWork<T, ID>,
|
|
{
|
|
}
|
|
|
|
/// Returns the system work queue (`system_wq`).
|
|
///
|
|
/// It is the one used by `schedule[_delayed]_work[_on]()`. Multi-CPU multi-threaded. There are
|
|
/// users which expect relatively short queue flush time.
|
|
///
|
|
/// Callers shouldn't queue work items which can run for too long.
|
|
pub fn system() -> &'static Queue {
|
|
// SAFETY: `system_wq` is a C global, always available.
|
|
unsafe { Queue::from_raw(bindings::system_wq) }
|
|
}
|
|
|
|
/// Returns the system high-priority work queue (`system_highpri_wq`).
|
|
///
|
|
/// It is similar to the one returned by [`system`] but for work items which require higher
|
|
/// scheduling priority.
|
|
pub fn system_highpri() -> &'static Queue {
|
|
// SAFETY: `system_highpri_wq` is a C global, always available.
|
|
unsafe { Queue::from_raw(bindings::system_highpri_wq) }
|
|
}
|
|
|
|
/// Returns the system work queue for potentially long-running work items (`system_long_wq`).
|
|
///
|
|
/// It is similar to the one returned by [`system`] but may host long running work items. Queue
|
|
/// flushing might take relatively long.
|
|
pub fn system_long() -> &'static Queue {
|
|
// SAFETY: `system_long_wq` is a C global, always available.
|
|
unsafe { Queue::from_raw(bindings::system_long_wq) }
|
|
}
|
|
|
|
/// Returns the system unbound work queue (`system_unbound_wq`).
|
|
///
|
|
/// Workers are not bound to any specific CPU, not concurrency managed, and all queued work items
|
|
/// are executed immediately as long as `max_active` limit is not reached and resources are
|
|
/// available.
|
|
pub fn system_unbound() -> &'static Queue {
|
|
// SAFETY: `system_unbound_wq` is a C global, always available.
|
|
unsafe { Queue::from_raw(bindings::system_unbound_wq) }
|
|
}
|
|
|
|
/// Returns the system freezable work queue (`system_freezable_wq`).
|
|
///
|
|
/// It is equivalent to the one returned by [`system`] except that it's freezable.
|
|
///
|
|
/// A freezable workqueue participates in the freeze phase of the system suspend operations. Work
|
|
/// items on the workqueue are drained and no new work item starts execution until thawed.
|
|
pub fn system_freezable() -> &'static Queue {
|
|
// SAFETY: `system_freezable_wq` is a C global, always available.
|
|
unsafe { Queue::from_raw(bindings::system_freezable_wq) }
|
|
}
|
|
|
|
/// Returns the system power-efficient work queue (`system_power_efficient_wq`).
|
|
///
|
|
/// It is inclined towards saving power and is converted to "unbound" variants if the
|
|
/// `workqueue.power_efficient` kernel parameter is specified; otherwise, it is similar to the one
|
|
/// returned by [`system`].
|
|
pub fn system_power_efficient() -> &'static Queue {
|
|
// SAFETY: `system_power_efficient_wq` is a C global, always available.
|
|
unsafe { Queue::from_raw(bindings::system_power_efficient_wq) }
|
|
}
|
|
|
|
/// Returns the system freezable power-efficient work queue (`system_freezable_power_efficient_wq`).
|
|
///
|
|
/// It is similar to the one returned by [`system_power_efficient`] except that is freezable.
|
|
///
|
|
/// A freezable workqueue participates in the freeze phase of the system suspend operations. Work
|
|
/// items on the workqueue are drained and no new work item starts execution until thawed.
|
|
pub fn system_freezable_power_efficient() -> &'static Queue {
|
|
// SAFETY: `system_freezable_power_efficient_wq` is a C global, always available.
|
|
unsafe { Queue::from_raw(bindings::system_freezable_power_efficient_wq) }
|
|
}
|
|
|
|
/// Returns the system bottom halves work queue (`system_bh_wq`).
|
|
///
|
|
/// It is similar to the one returned by [`system`] but for work items which
|
|
/// need to run from a softirq context.
|
|
pub fn system_bh() -> &'static Queue {
|
|
// SAFETY: `system_bh_wq` is a C global, always available.
|
|
unsafe { Queue::from_raw(bindings::system_bh_wq) }
|
|
}
|
|
|
|
/// Returns the system bottom halves high-priority work queue (`system_bh_highpri_wq`).
|
|
///
|
|
/// It is similar to the one returned by [`system_bh`] but for work items which
|
|
/// require higher scheduling priority.
|
|
pub fn system_bh_highpri() -> &'static Queue {
|
|
// SAFETY: `system_bh_highpri_wq` is a C global, always available.
|
|
unsafe { Queue::from_raw(bindings::system_bh_highpri_wq) }
|
|
}
|