[PATCH 1/2] rust: sync: lock: allow fallible initializers in Lock::new

[Ivan Tverdokhleb]

Currently Lock::new() only accepts an infallible initializer for the
protected data, because impl PinInit<T> defaults the error type to
Infallible. This prevents wrapping a fallible initializer, such as
Opaque::try_ffi_init(), in a Mutex or SpinLock.

Make Lock::new() generic over the error type E, so that it accepts any
impl PinInit<T, E> and returns impl PinInit<Self, E>. E must implement
From<Infallible>, since initializing the lock state itself cannot fail.

This is needed, for example, by the GPU buddy allocator, which has a
TODO to move its gpu_buddy structure inside the mutex.

Signed-off-by: Ivan Tverdokhleb <mbkchelofficialdev@xxxxxxxxx>
---
 rust/kernel/sync/lock.rs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index 10b6b5e9b024..26c071088b02 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs
@@ -128,11 +128,11 @@ 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: impl PinInit<T>,
+    pub fn new<E: core::convert::From<core::convert::Infallible>>(
+        t: impl PinInit<T, E>,
         name: &'static CStr,
         key: Pin<&'static LockClassKey>,
-    ) -> impl PinInit<Self> {
+    ) -> impl PinInit<Self, E> {
         pin_init!(Self {
             data <- UnsafeCell::pin_init(t),
             _pin: PhantomPinned,
@@ -141,7 +141,7 @@ pub fn new(
             state <- Opaque::ffi_init(|slot| unsafe {
                 B::init(slot, name.as_char_ptr(), key.as_ptr())
             }),
-        })
+        }? E)
     }
 }
 
-- 
2.56.1