linux-kernel - Re: [PATCH v2 8/8] rust: workqueue: add examples

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Date:   Fri,  2 Jun 2023 09:39:25 +0000
From:   Alice Ryhl <aliceryhl@...gle.com>
To:     gary@...yguo.net
Cc:     alex.gaynor@...il.com, aliceryhl@...gle.com,
        benno.lossin@...ton.me, bjorn3_gh@...tonmail.com,
        boqun.feng@...il.com, jiangshanlai@...il.com,
        linux-kernel@...r.kernel.org, ojeda@...nel.org,
        patches@...ts.linux.dev, rust-for-linux@...r.kernel.org,
        tj@...nel.org, wedsonaf@...il.com
Subject: Re: [PATCH v2 8/8] rust: workqueue: add examples

Gary Guo <gary@...yguo.net> writes:
> On Thu,  1 Jun 2023 13:49:46 +0000
> Alice Ryhl <aliceryhl@...gle.com> wrote:
>> 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@...gle.com>
>> ---
>>  rust/kernel/workqueue.rs | 104 +++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 104 insertions(+)
>> 
>> diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
>> index c302e8b8624b..cefcf43ff40e 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(),
>> +//!         }))
>> +//!     }
>> +//! }
>> +//!
>> +//! 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(),
>> +//!             work_2 <- Work::new(),
>> +//!         }))
>> +//!     }
>> +//! }
>> +//!
>> +//! 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);
> 
> Nothing bad about explicit, but I just want to confirm that you could
> write
> 
> 	let _ = workqueue::system().enqueue::<_, 1>(val);
> 
> here, right?

Yes, you can also do that.