In preparation to support Lock<T> where T is pinned, the first thing that
needs to be done is to structurally pin the 'data' member. This switches
the 't' parameter in Lock<T>::new() to take in an impl PinInit<T> instead
of a plain T. This in turn uses the blanket implementation "impl PinInit<T>
for T".

Subsequent patches will touch on Guard<T>.

Link: https://github.com/Rust-for-Linux/linux/issues/1181
Suggested-by: Benno Lossin <lossin@kernel.org>
Suggested-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Daniel Almeida <daniel.almeida@collabora.com>
---
 rust/kernel/sync/lock.rs | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index b482f34bf0ce817e70f7a0da93443f77dd19ea79..9242790d15dbf65d66518d060a8a777aac558cfc 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs
@@ -11,7 +11,7 @@
     types::{NotThreadSafe, Opaque, ScopeGuard},
 };
 use core::{cell::UnsafeCell, marker::PhantomPinned, pin::Pin};
-use pin_init::{pin_data, pin_init, PinInit};
+use pin_init::{pin_data, pin_init, PinInit, Wrapper};
 
 pub mod mutex;
 pub mod spinlock;
@@ -115,6 +115,7 @@ pub struct Lock<T: ?Sized, B: Backend> {
     _pin: PhantomPinned,
 
     /// The data protected by the lock.
+    #[pin]
     pub(crate) data: UnsafeCell<T>,
 }
 
@@ -127,9 +128,13 @@ unsafe impl<T: ?Sized + Send, B: Backend> Sync for Lock<T, B> {}
 
 impl<T, B: Backend> Lock<T, B> {
     /// Constructs a new lock initialiser.
-    pub fn new(t: T, name: &'static CStr, key: Pin<&'static LockClassKey>) -> impl PinInit<Self> {
+    pub fn new(
+        t: impl PinInit<T>,
+        name: &'static CStr,
+        key: Pin<&'static LockClassKey>,
+    ) -> impl PinInit<Self> {
         pin_init!(Self {
-            data: UnsafeCell::new(t),
+            data <- UnsafeCell::pin_init(t),
             _pin: PhantomPinned,
             // SAFETY: `slot` is valid while the closure is called and both `name` and `key` have
             // static lifetimes so they live indefinitely.

-- 
2.50.1