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Date:   Tue, 11 Jul 2023 09:33:03 +0000
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Subject: [PATCH v3 9/9] rust: workqueue: add examples
From:   Alice Ryhl <aliceryhl@google.com>
To:     rust-for-linux@vger.kernel.org, Tejun Heo <tj@kernel.org>,
        Miguel Ojeda <ojeda@kernel.org>
Cc:     Lai Jiangshan <jiangshanlai@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        "=?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?=" <bjorn3_gh@protonmail.com>,
        Benno Lossin <benno.lossin@proton.me>,
        Alice Ryhl <aliceryhl@google.com>,
        linux-kernel@vger.kernel.org, patches@lists.linux.dev,
        Martin Rodriguez Reboredo <yakoyoku@gmail.com>,
        Andreas Hindborg <nmi@metaspace.dk>
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Precedence: bulk

This adds two examples of how to use the workqueue. The first example
shows how to use it when you only have one `work_struct` field, and the
second example shows how to use it when you have multiple `work_struct`
fields.

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Andreas Hindborg (Samsung) <nmi@metaspace.dk>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
---
v2 -> v3:
 * Use LockClassKey in constructors in examples.
 * Add Reviewed-by from Martin, Gary, Andreas, Benno.

 rust/kernel/workqueue.rs | 104 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)

diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index 3a3a8b52bfd9..482d3eeae7d8 100644
--- a/rust/kernel/workqueue.rs
+++ b/rust/kernel/workqueue.rs
@@ -26,6 +26,110 @@
 //!  * 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::prelude::*;
+//! use kernel::sync::Arc;
+//! use kernel::workqueue::{self, 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 <- Work::new(kernel::static_lock_class!()),
+//!         }))
+//!     }
+//! }
+//!
+//! impl WorkItem for MyStruct {
+//!     type Pointer = Arc<MyStruct>;
+//!
+//!     fn run(this: Arc<MyStruct>) {
+//!         pr_info!("The value is: {}", 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);
+//! }
+//! ```
+//!
+//! The following example shows how multiple `work_struct` fields can be used:
+//!
+//! ```
+//! use kernel::prelude::*;
+//! use kernel::sync::Arc;
+//! use kernel::workqueue::{self, 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 <- Work::new(kernel::static_lock_class!()),
+//!             work_2 <- Work::new(kernel::static_lock_class!()),
+//!         }))
+//!     }
+//! }
+//!
+//! impl WorkItem<1> for MyStruct {
+//!     type Pointer = Arc<MyStruct>;
+//!
+//!     fn run(this: Arc<MyStruct>) {
+//!         pr_info!("The value is: {}", this.value_1);
+//!     }
+//! }
+//!
+//! impl WorkItem<2> for MyStruct {
+//!     type Pointer = Arc<MyStruct>;
+//!
+//!     fn run(this: Arc<MyStruct>) {
+//!         pr_info!("The second value is: {}", 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);
+//! }
+//! ```
+//!
 //! C header: [`include/linux/workqueue.h`](../../../../include/linux/workqueue.h)
 
 use crate::{bindings, prelude::*, sync::Arc, sync::LockClassKey, types::Opaque};
-- 
2.41.0.255.g8b1d071c50-goog