rust: sync: update `Arc` and `UniqueArc` to take allocation flags

We also remove the `try_` prefix to align with how `Box` and `Vec` are
providing methods now.

`init` is temporarily updated with uses of GFP_KERNEL. These will be
updated in a subsequent patch to take flags as well.
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Wedson Almeida Filho <walmeida@microsoft.com>
Link: https://lore.kernel.org/r/20240328013603.206764-9-wedsonaf@gmail.comSigned-off-by: Miguel Ojeda <ojeda@kernel.org>

rust/kernel/init.rs

@@ -1189,7 +1189,7 @@ fn try_pin_init<E>(init: impl PinInit<T, E>) -> Result<Pin<Self>, E>
     where
         E: From<AllocError>,
     {
-        let mut this = UniqueArc::try_new_uninit()?;
+        let mut this = UniqueArc::new_uninit(GFP_KERNEL)?;
         let slot = this.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
         // slot is valid and will not be moved, because we pin it later.
@@ -1203,7 +1203,7 @@ fn try_init<E>(init: impl Init<T, E>) -> Result<Self, E>
     where
         E: From<AllocError>,
     {
-        let mut this = UniqueArc::try_new_uninit()?;
+        let mut this = UniqueArc::new_uninit(GFP_KERNEL)?;
         let slot = this.as_mut_ptr();
         // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
         // slot is valid.

rust/kernel/sync/arc.rs

@@ -16,7 +16,7 @@
 //! [`Arc`]: https://doc.rust-lang.org/std/sync/struct.Arc.html
 
 use crate::{
-    alloc::{box_ext::BoxExt, flags::*},
+    alloc::{box_ext::BoxExt, Flags},
     bindings,
     error::{self, Error},
     init::{self, InPlaceInit, Init, PinInit},
@@ -58,7 +58,7 @@
 /// }
 ///
 /// // Create a refcounted instance of `Example`.
-/// let obj = Arc::try_new(Example { a: 10, b: 20 })?;
+/// let obj = Arc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?;
 ///
 /// // Get a new pointer to `obj` and increment the refcount.
 /// let cloned = obj.clone();
@@ -97,7 +97,7 @@
 ///     }
 /// }
 ///
-/// let obj = Arc::try_new(Example { a: 10, b: 20 })?;
+/// let obj = Arc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?;
 /// obj.use_reference();
 /// obj.take_over();
 /// # Ok::<(), Error>(())
@@ -120,7 +120,7 @@
 /// impl MyTrait for Example {}
 ///
 /// // `obj` has type `Arc<Example>`.
-/// let obj: Arc<Example> = Arc::try_new(Example)?;
+/// let obj: Arc<Example> = Arc::new(Example, GFP_KERNEL)?;
 ///
 /// // `coerced` has type `Arc<dyn MyTrait>`.
 /// let coerced: Arc<dyn MyTrait> = obj;
@@ -163,7 +163,7 @@ unsafe impl<T: ?Sized + Sync + Send> Sync for Arc<T> {}
 
 impl<T> Arc<T> {
     /// Constructs a new reference counted instance of `T`.
-    pub fn try_new(contents: T) -> Result<Self, AllocError> {
+    pub fn new(contents: T, flags: Flags) -> Result<Self, AllocError> {
         // INVARIANT: The refcount is initialised to a non-zero value.
         let value = ArcInner {
             // SAFETY: There are no safety requirements for this FFI call.
@@ -171,7 +171,7 @@ pub fn try_new(contents: T) -> Result<Self, AllocError> {
             data: contents,
         };
 
-        let inner = <Box<_> as BoxExt<_>>::new(value, GFP_KERNEL)?;
+        let inner = <Box<_> as BoxExt<_>>::new(value, flags)?;
 
         // SAFETY: We just created `inner` with a reference count of 1, which is owned by the new
         // `Arc` object.
@@ -388,7 +388,7 @@ fn from(item: Pin<UniqueArc<T>>) -> Self {
 ///     e.into()
 /// }
 ///
-/// let obj = Arc::try_new(Example)?;
+/// let obj = Arc::new(Example, GFP_KERNEL)?;
 /// let cloned = do_something(obj.as_arc_borrow());
 ///
 /// // Assert that both `obj` and `cloned` point to the same underlying object.
@@ -412,7 +412,7 @@ fn from(item: Pin<UniqueArc<T>>) -> Self {
 ///     }
 /// }
 ///
-/// let obj = Arc::try_new(Example { a: 10, b: 20 })?;
+/// let obj = Arc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?;
 /// obj.as_arc_borrow().use_reference();
 /// # Ok::<(), Error>(())
 /// ```
@@ -500,7 +500,7 @@ fn deref(&self) -> &Self::Target {
 /// }
 ///
 /// fn test() -> Result<Arc<Example>> {
-///     let mut x = UniqueArc::try_new(Example { a: 10, b: 20 })?;
+///     let mut x = UniqueArc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?;
 ///     x.a += 1;
 ///     x.b += 1;
 ///     Ok(x.into())
@@ -523,7 +523,7 @@ fn deref(&self) -> &Self::Target {
 /// }
 ///
 /// fn test() -> Result<Arc<Example>> {
-///     let x = UniqueArc::try_new_uninit()?;
+///     let x = UniqueArc::new_uninit(GFP_KERNEL)?;
 ///     Ok(x.write(Example { a: 10, b: 20 }).into())
 /// }
 ///
@@ -543,7 +543,7 @@ fn deref(&self) -> &Self::Target {
 /// }
 ///
 /// fn test() -> Result<Arc<Example>> {
-///     let mut pinned = Pin::from(UniqueArc::try_new(Example { a: 10, b: 20 })?);
+///     let mut pinned = Pin::from(UniqueArc::new(Example { a: 10, b: 20 }, GFP_KERNEL)?);
 ///     // We can modify `pinned` because it is `Unpin`.
 ///     pinned.as_mut().a += 1;
 ///     Ok(pinned.into())
@@ -557,15 +557,15 @@ pub struct UniqueArc<T: ?Sized> {
 
 impl<T> UniqueArc<T> {
     /// Tries to allocate a new [`UniqueArc`] instance.
-    pub fn try_new(value: T) -> Result<Self, AllocError> {
+    pub fn new(value: T, flags: Flags) -> Result<Self, AllocError> {
         Ok(Self {
             // INVARIANT: The newly-created object has a refcount of 1.
-            inner: Arc::try_new(value)?,
+            inner: Arc::new(value, flags)?,
         })
     }
 
     /// Tries to allocate a new [`UniqueArc`] instance whose contents are not initialised yet.
-    pub fn try_new_uninit() -> Result<UniqueArc<MaybeUninit<T>>, AllocError> {
+    pub fn new_uninit(_flags: Flags) -> Result<UniqueArc<MaybeUninit<T>>, AllocError> {
         // INVARIANT: The refcount is initialised to a non-zero value.
         let inner = Box::try_init::<AllocError>(try_init!(ArcInner {
             // SAFETY: There are no safety requirements for this FFI call.

samples/rust/rust_print.rs

@@ -18,8 +18,8 @@
 fn arc_print() -> Result {
     use kernel::sync::*;
 
-    let a = Arc::try_new(1)?;
-    let b = UniqueArc::try_new("hello, world")?;
+    let a = Arc::new(1, GFP_KERNEL)?;
+    let b = UniqueArc::new("hello, world", GFP_KERNEL)?;
 
     // Prints the value of data in `a`.
     pr_info!("{}", a);