[PATCH v2 3/3] rust: workqueue: add `#[pin_data]` to `Work`

[Benno Lossin <benno.lossin@proton.me>]

The previous two patches made it possible to add `#[pin_data]` on
structs with default generic parameter values.
This patch makes `Work` use `#[pin_data]` and removes an invocation of
`pin_init_from_closure`. This function is intended as a low level manual
escape hatch, so it is better to rely on the safe `pin_init!` macro.

Signed-off-by: Benno Lossin <benno.lossin@proton.me>
---
v1 -> v2:
- improve commit message wording
- change `:` to `<-` in `pin_init!` invocation

 rust/kernel/workqueue.rs | 33 ++++++++++++++++++---------------
 1 file changed, 18 insertions(+), 15 deletions(-)

diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index b67fb1ba168e..4a9fb7d06d20 100644
--- a/rust/kernel/workqueue.rs
+++ b/rust/kernel/workqueue.rs
@@ -334,8 +334,10 @@ pub trait WorkItem<const ID: u64 = 0> {
 /// 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.
+#[pin_data]
 #[repr(transparent)]
 pub struct Work<T: ?Sized, const ID: u64 = 0> {
+    #[pin]
     work: Opaque<bindings::work_struct>,
     _inner: PhantomData<T>,
 }
@@ -357,21 +359,22 @@ pub fn new(name: &'static CStr, key: &'static LockClassKey) -> impl PinInit<Self
     where
         T: WorkItem<ID>,
     {
-        // SAFETY: The `WorkItemPointer` implementation promises that `run` can be used as the work
-        // item function.
-        unsafe {
-            kernel::init::pin_init_from_closure(move |slot| {
-                let slot = Self::raw_get(slot);
-                bindings::init_work_with_key(
-                    slot,
-                    Some(T::Pointer::run),
-                    false,
-                    name.as_char_ptr(),
-                    key.as_ptr(),
-                );
-                Ok(())
-            })
-        }
+        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`.
-- 
2.42.0