diff options
Diffstat (limited to 'rust/kernel/sync')
| -rw-r--r-- | rust/kernel/sync/arc.rs | 57 | ||||
| -rw-r--r-- | rust/kernel/sync/condvar.rs | 1 | ||||
| -rw-r--r-- | rust/kernel/sync/lock.rs | 7 | ||||
| -rw-r--r-- | rust/kernel/sync/lock/mutex.rs | 1 | ||||
| -rw-r--r-- | rust/kernel/sync/lock/spinlock.rs | 1 |
5 files changed, 57 insertions, 10 deletions
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index 172f563976a9..77cdbcf7bd2e 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -24,13 +24,13 @@ use crate::{ }; use alloc::boxed::Box; use core::{ - alloc::AllocError, + alloc::{AllocError, Layout}, fmt, marker::{PhantomData, Unsize}, mem::{ManuallyDrop, MaybeUninit}, ops::{Deref, DerefMut}, pin::Pin, - ptr::NonNull, + ptr::{NonNull, Pointee}, }; use macros::pin_data; @@ -73,6 +73,7 @@ mod std_vendor; /// assert_eq!(cloned.b, 20); /// /// // The refcount drops to zero when `cloned` goes out of scope, and the memory is freed. +/// # Ok::<(), Error>(()) /// ``` /// /// Using `Arc<T>` as the type of `self`: @@ -98,6 +99,7 @@ mod std_vendor; /// let obj = Arc::try_new(Example { a: 10, b: 20 })?; /// obj.use_reference(); /// obj.take_over(); +/// # Ok::<(), Error>(()) /// ``` /// /// Coercion from `Arc<Example>` to `Arc<dyn MyTrait>`: @@ -121,6 +123,7 @@ mod std_vendor; /// /// // `coerced` has type `Arc<dyn MyTrait>`. /// let coerced: Arc<dyn MyTrait> = obj; +/// # Ok::<(), Error>(()) /// ``` pub struct Arc<T: ?Sized> { ptr: NonNull<ArcInner<T>>, @@ -212,6 +215,48 @@ impl<T: ?Sized> Arc<T> { } } + /// Convert the [`Arc`] into a raw pointer. + /// + /// The raw pointer has ownership of the refcount that this Arc object owned. + pub fn into_raw(self) -> *const T { + let ptr = self.ptr.as_ptr(); + core::mem::forget(self); + // SAFETY: The pointer is valid. + unsafe { core::ptr::addr_of!((*ptr).data) } + } + + /// Recreates an [`Arc`] instance previously deconstructed via [`Arc::into_raw`]. + /// + /// # Safety + /// + /// `ptr` must have been returned by a previous call to [`Arc::into_raw`]. Additionally, it + /// must not be called more than once for each previous call to [`Arc::into_raw`]. + pub unsafe fn from_raw(ptr: *const T) -> Self { + let refcount_layout = Layout::new::<bindings::refcount_t>(); + // SAFETY: The caller guarantees that the pointer is valid. + let val_layout = Layout::for_value(unsafe { &*ptr }); + // SAFETY: We're computing the layout of a real struct that existed when compiling this + // binary, so its layout is not so large that it can trigger arithmetic overflow. + let val_offset = unsafe { refcount_layout.extend(val_layout).unwrap_unchecked().1 }; + + let metadata: <T as Pointee>::Metadata = core::ptr::metadata(ptr); + // SAFETY: The metadata of `T` and `ArcInner<T>` is the same because `ArcInner` is a struct + // with `T` as its last field. + // + // This is documented at: + // <https://doc.rust-lang.org/std/ptr/trait.Pointee.html>. + let metadata: <ArcInner<T> as Pointee>::Metadata = + unsafe { core::mem::transmute_copy(&metadata) }; + // SAFETY: The pointer is in-bounds of an allocation both before and after offsetting the + // pointer, since it originates from a previous call to `Arc::into_raw` and is still valid. + let ptr = unsafe { (ptr as *mut u8).sub(val_offset) as *mut () }; + let ptr = core::ptr::from_raw_parts_mut(ptr, metadata); + + // SAFETY: By the safety requirements we know that `ptr` came from `Arc::into_raw`, so the + // reference count held then will be owned by the new `Arc` object. + unsafe { Self::from_inner(NonNull::new_unchecked(ptr)) } + } + /// Returns an [`ArcBorrow`] from the given [`Arc`]. /// /// This is useful when the argument of a function call is an [`ArcBorrow`] (e.g., in a method @@ -299,7 +344,7 @@ impl<T: ?Sized> Drop for Arc<T> { // The count reached zero, we must free the memory. // // SAFETY: The pointer was initialised from the result of `Box::leak`. - unsafe { Box::from_raw(self.ptr.as_ptr()) }; + unsafe { drop(Box::from_raw(self.ptr.as_ptr())) }; } } } @@ -336,7 +381,7 @@ impl<T: ?Sized> From<Pin<UniqueArc<T>>> for Arc<T> { /// # Example /// /// ``` -/// use crate::sync::{Arc, ArcBorrow}; +/// use kernel::sync::{Arc, ArcBorrow}; /// /// struct Example; /// @@ -349,12 +394,13 @@ impl<T: ?Sized> From<Pin<UniqueArc<T>>> for Arc<T> { /// /// // Assert that both `obj` and `cloned` point to the same underlying object. /// assert!(core::ptr::eq(&*obj, &*cloned)); +/// # Ok::<(), Error>(()) /// ``` /// /// Using `ArcBorrow<T>` as the type of `self`: /// /// ``` -/// use crate::sync::{Arc, ArcBorrow}; +/// use kernel::sync::{Arc, ArcBorrow}; /// /// struct Example { /// a: u32, @@ -369,6 +415,7 @@ impl<T: ?Sized> From<Pin<UniqueArc<T>>> for Arc<T> { /// /// let obj = Arc::try_new(Example { a: 10, b: 20 })?; /// obj.as_arc_borrow().use_reference(); +/// # Ok::<(), Error>(()) /// ``` pub struct ArcBorrow<'a, T: ?Sized + 'a> { inner: NonNull<ArcInner<T>>, diff --git a/rust/kernel/sync/condvar.rs b/rust/kernel/sync/condvar.rs index ed353399c4e5..b679b6f6dbeb 100644 --- a/rust/kernel/sync/condvar.rs +++ b/rust/kernel/sync/condvar.rs @@ -91,7 +91,6 @@ unsafe impl Sync for CondVar {} impl CondVar { /// Constructs a new condvar initialiser. - #[allow(clippy::new_ret_no_self)] pub fn new(name: &'static CStr, key: &'static LockClassKey) -> impl PinInit<Self> { pin_init!(Self { _pin: PhantomPinned, diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs index a2216325632d..f12a684bc957 100644 --- a/rust/kernel/sync/lock.rs +++ b/rust/kernel/sync/lock.rs @@ -72,8 +72,8 @@ pub unsafe trait Backend { /// A mutual exclusion primitive. /// -/// Exposes one of the kernel locking primitives. Which one is exposed depends on the lock backend -/// specified as the generic parameter `B`. +/// Exposes one of the kernel locking primitives. Which one is exposed depends on the lock +/// [`Backend`] specified as the generic parameter `B`. #[pin_data] pub struct Lock<T: ?Sized, B: Backend> { /// The kernel lock object. @@ -99,7 +99,6 @@ unsafe impl<T: ?Sized + Send, B: Backend> Sync for Lock<T, B> {} impl<T, B: Backend> Lock<T, B> { /// Constructs a new lock initialiser. - #[allow(clippy::new_ret_no_self)] pub fn new(t: T, name: &'static CStr, key: &'static LockClassKey) -> impl PinInit<Self> { pin_init!(Self { data: UnsafeCell::new(t), @@ -126,7 +125,7 @@ impl<T: ?Sized, B: Backend> Lock<T, B> { /// A lock guard. /// -/// Allows mutual exclusion primitives that implement the `Backend` trait to automatically unlock +/// Allows mutual exclusion primitives that implement the [`Backend`] trait to automatically unlock /// when a guard goes out of scope. It also provides a safe and convenient way to access the data /// protected by the lock. #[must_use = "the lock unlocks immediately when the guard is unused"] diff --git a/rust/kernel/sync/lock/mutex.rs b/rust/kernel/sync/lock/mutex.rs index 923472f04af4..09276fedc091 100644 --- a/rust/kernel/sync/lock/mutex.rs +++ b/rust/kernel/sync/lock/mutex.rs @@ -63,6 +63,7 @@ macro_rules! new_mutex { /// assert_eq!(e.c, 10); /// assert_eq!(e.d.lock().a, 20); /// assert_eq!(e.d.lock().b, 30); +/// # Ok::<(), Error>(()) /// ``` /// /// The following example shows how to use interior mutability to modify the contents of a struct diff --git a/rust/kernel/sync/lock/spinlock.rs b/rust/kernel/sync/lock/spinlock.rs index 979b56464a4e..91eb2c9e9123 100644 --- a/rust/kernel/sync/lock/spinlock.rs +++ b/rust/kernel/sync/lock/spinlock.rs @@ -61,6 +61,7 @@ macro_rules! new_spinlock { /// assert_eq!(e.c, 10); /// assert_eq!(e.d.lock().a, 20); /// assert_eq!(e.d.lock().b, 30); +/// # Ok::<(), Error>(()) /// ``` /// /// The following example shows how to use interior mutability to modify the contents of a struct |