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-rw-r--r--MAINTAINERS11
-rw-r--r--rust/bindings/bindings_helper.h6
-rw-r--r--rust/helpers/helpers.c1
-rw-r--r--rust/helpers/xarray.c28
-rw-r--r--rust/kernel/alloc/kbox.rs38
-rw-r--r--rust/kernel/lib.rs1
-rw-r--r--rust/kernel/miscdevice.rs10
-rw-r--r--rust/kernel/pci.rs2
-rw-r--r--rust/kernel/platform.rs2
-rw-r--r--rust/kernel/sync/arc.rs21
-rw-r--r--rust/kernel/types.rs46
-rw-r--r--rust/kernel/xarray.rs275
12 files changed, 392 insertions, 49 deletions
diff --git a/MAINTAINERS b/MAINTAINERS
index 870403d705d3..b659fb27ab63 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -26408,6 +26408,17 @@ F: lib/test_xarray.c
F: lib/xarray.c
F: tools/testing/radix-tree
+XARRAY API [RUST]
+M: Tamir Duberstein <tamird@gmail.com>
+M: Andreas Hindborg <a.hindborg@kernel.org>
+L: rust-for-linux@vger.kernel.org
+S: Supported
+W: https://rust-for-linux.com
+B: https://github.com/Rust-for-Linux/linux/issues
+C: https://rust-for-linux.zulipchat.com
+T: git https://github.com/Rust-for-Linux/linux.git xarray-next
+F: rust/kernel/xarray.rs
+
XBOX DVD IR REMOTE
M: Benjamin Valentin <benpicco@googlemail.com>
S: Maintained
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index ab37e1d35c70..e0bcd130b494 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -37,6 +37,7 @@
#include <linux/tracepoint.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
+#include <linux/xarray.h>
#include <trace/events/rust_sample.h>
#if defined(CONFIG_DRM_PANIC_SCREEN_QR_CODE)
@@ -55,3 +56,8 @@ const gfp_t RUST_CONST_HELPER___GFP_ZERO = __GFP_ZERO;
const gfp_t RUST_CONST_HELPER___GFP_HIGHMEM = ___GFP_HIGHMEM;
const gfp_t RUST_CONST_HELPER___GFP_NOWARN = ___GFP_NOWARN;
const blk_features_t RUST_CONST_HELPER_BLK_FEAT_ROTATIONAL = BLK_FEAT_ROTATIONAL;
+
+const xa_mark_t RUST_CONST_HELPER_XA_PRESENT = XA_PRESENT;
+
+const gfp_t RUST_CONST_HELPER_XA_FLAGS_ALLOC = XA_FLAGS_ALLOC;
+const gfp_t RUST_CONST_HELPER_XA_FLAGS_ALLOC1 = XA_FLAGS_ALLOC1;
diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
index 1e7c84df7252..80785b1e7a63 100644
--- a/rust/helpers/helpers.c
+++ b/rust/helpers/helpers.c
@@ -38,3 +38,4 @@
#include "vmalloc.c"
#include "wait.c"
#include "workqueue.c"
+#include "xarray.c"
diff --git a/rust/helpers/xarray.c b/rust/helpers/xarray.c
new file mode 100644
index 000000000000..60b299f11451
--- /dev/null
+++ b/rust/helpers/xarray.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/xarray.h>
+
+int rust_helper_xa_err(void *entry)
+{
+ return xa_err(entry);
+}
+
+void rust_helper_xa_init_flags(struct xarray *xa, gfp_t flags)
+{
+ return xa_init_flags(xa, flags);
+}
+
+int rust_helper_xa_trylock(struct xarray *xa)
+{
+ return xa_trylock(xa);
+}
+
+void rust_helper_xa_lock(struct xarray *xa)
+{
+ return xa_lock(xa);
+}
+
+void rust_helper_xa_unlock(struct xarray *xa)
+{
+ return xa_unlock(xa);
+}
diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs
index 604d12c6f5bd..a0638405bb9a 100644
--- a/rust/kernel/alloc/kbox.rs
+++ b/rust/kernel/alloc/kbox.rs
@@ -360,68 +360,70 @@ where
}
}
-impl<T: 'static, A> ForeignOwnable for Box<T, A>
+// SAFETY: The `into_foreign` function returns a pointer that is well-aligned.
+unsafe impl<T: 'static, A> ForeignOwnable for Box<T, A>
where
A: Allocator,
{
+ type PointedTo = T;
type Borrowed<'a> = &'a T;
type BorrowedMut<'a> = &'a mut T;
- fn into_foreign(self) -> *mut crate::ffi::c_void {
- Box::into_raw(self).cast()
+ fn into_foreign(self) -> *mut Self::PointedTo {
+ Box::into_raw(self)
}
- unsafe fn from_foreign(ptr: *mut crate::ffi::c_void) -> Self {
+ unsafe fn from_foreign(ptr: *mut Self::PointedTo) -> Self {
// SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
// call to `Self::into_foreign`.
- unsafe { Box::from_raw(ptr.cast()) }
+ unsafe { Box::from_raw(ptr) }
}
- unsafe fn borrow<'a>(ptr: *mut crate::ffi::c_void) -> &'a T {
+ unsafe fn borrow<'a>(ptr: *mut Self::PointedTo) -> &'a T {
// SAFETY: The safety requirements of this method ensure that the object remains alive and
// immutable for the duration of 'a.
- unsafe { &*ptr.cast() }
+ unsafe { &*ptr }
}
- unsafe fn borrow_mut<'a>(ptr: *mut crate::ffi::c_void) -> &'a mut T {
- let ptr = ptr.cast();
+ unsafe fn borrow_mut<'a>(ptr: *mut Self::PointedTo) -> &'a mut T {
// SAFETY: The safety requirements of this method ensure that the pointer is valid and that
// nothing else will access the value for the duration of 'a.
unsafe { &mut *ptr }
}
}
-impl<T: 'static, A> ForeignOwnable for Pin<Box<T, A>>
+// SAFETY: The `into_foreign` function returns a pointer that is well-aligned.
+unsafe impl<T: 'static, A> ForeignOwnable for Pin<Box<T, A>>
where
A: Allocator,
{
+ type PointedTo = T;
type Borrowed<'a> = Pin<&'a T>;
type BorrowedMut<'a> = Pin<&'a mut T>;
- fn into_foreign(self) -> *mut crate::ffi::c_void {
+ fn into_foreign(self) -> *mut Self::PointedTo {
// SAFETY: We are still treating the box as pinned.
- Box::into_raw(unsafe { Pin::into_inner_unchecked(self) }).cast()
+ Box::into_raw(unsafe { Pin::into_inner_unchecked(self) })
}
- unsafe fn from_foreign(ptr: *mut crate::ffi::c_void) -> Self {
+ unsafe fn from_foreign(ptr: *mut Self::PointedTo) -> Self {
// SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
// call to `Self::into_foreign`.
- unsafe { Pin::new_unchecked(Box::from_raw(ptr.cast())) }
+ unsafe { Pin::new_unchecked(Box::from_raw(ptr)) }
}
- unsafe fn borrow<'a>(ptr: *mut crate::ffi::c_void) -> Pin<&'a T> {
+ unsafe fn borrow<'a>(ptr: *mut Self::PointedTo) -> Pin<&'a T> {
// SAFETY: The safety requirements for this function ensure that the object is still alive,
// so it is safe to dereference the raw pointer.
// The safety requirements of `from_foreign` also ensure that the object remains alive for
// the lifetime of the returned value.
- let r = unsafe { &*ptr.cast() };
+ let r = unsafe { &*ptr };
// SAFETY: This pointer originates from a `Pin<Box<T>>`.
unsafe { Pin::new_unchecked(r) }
}
- unsafe fn borrow_mut<'a>(ptr: *mut crate::ffi::c_void) -> Pin<&'a mut T> {
- let ptr = ptr.cast();
+ unsafe fn borrow_mut<'a>(ptr: *mut Self::PointedTo) -> Pin<&'a mut T> {
// SAFETY: The safety requirements for this function ensure that the object is still alive,
// so it is safe to dereference the raw pointer.
// The safety requirements of `from_foreign` also ensure that the object remains alive for
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 28007be98fba..6e9287136cac 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -102,6 +102,7 @@ pub mod transmute;
pub mod types;
pub mod uaccess;
pub mod workqueue;
+pub mod xarray;
#[doc(hidden)]
pub use bindings;
diff --git a/rust/kernel/miscdevice.rs b/rust/kernel/miscdevice.rs
index fa9ecc42602a..b4c5f74de23d 100644
--- a/rust/kernel/miscdevice.rs
+++ b/rust/kernel/miscdevice.rs
@@ -200,7 +200,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
// type.
//
// SAFETY: The open call of a file can access the private data.
- unsafe { (*raw_file).private_data = ptr.into_foreign() };
+ unsafe { (*raw_file).private_data = ptr.into_foreign().cast() };
0
}
@@ -211,7 +211,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
/// must be associated with a `MiscDeviceRegistration<T>`.
unsafe extern "C" fn release(_inode: *mut bindings::inode, file: *mut bindings::file) -> c_int {
// SAFETY: The release call of a file owns the private data.
- let private = unsafe { (*file).private_data };
+ let private = unsafe { (*file).private_data }.cast();
// SAFETY: The release call of a file owns the private data.
let ptr = unsafe { <T::Ptr as ForeignOwnable>::from_foreign(private) };
@@ -228,7 +228,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
/// `file` must be a valid file that is associated with a `MiscDeviceRegistration<T>`.
unsafe extern "C" fn ioctl(file: *mut bindings::file, cmd: c_uint, arg: c_ulong) -> c_long {
// SAFETY: The ioctl call of a file can access the private data.
- let private = unsafe { (*file).private_data };
+ let private = unsafe { (*file).private_data }.cast();
// SAFETY: Ioctl calls can borrow the private data of the file.
let device = unsafe { <T::Ptr as ForeignOwnable>::borrow(private) };
@@ -253,7 +253,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
arg: c_ulong,
) -> c_long {
// SAFETY: The compat ioctl call of a file can access the private data.
- let private = unsafe { (*file).private_data };
+ let private = unsafe { (*file).private_data }.cast();
// SAFETY: Ioctl calls can borrow the private data of the file.
let device = unsafe { <T::Ptr as ForeignOwnable>::borrow(private) };
@@ -274,7 +274,7 @@ impl<T: MiscDevice> MiscdeviceVTable<T> {
/// - `seq_file` must be a valid `struct seq_file` that we can write to.
unsafe extern "C" fn show_fdinfo(seq_file: *mut bindings::seq_file, file: *mut bindings::file) {
// SAFETY: The release call of a file owns the private data.
- let private = unsafe { (*file).private_data };
+ let private = unsafe { (*file).private_data }.cast();
// SAFETY: Ioctl calls can borrow the private data of the file.
let device = unsafe { <T::Ptr as ForeignOwnable>::borrow(private) };
// SAFETY:
diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index c97d6d470b28..3aeb1250c27f 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -89,7 +89,7 @@ impl<T: Driver + 'static> Adapter<T> {
extern "C" fn remove_callback(pdev: *mut bindings::pci_dev) {
// SAFETY: The PCI bus only ever calls the remove callback with a valid pointer to a
// `struct pci_dev`.
- let ptr = unsafe { bindings::pci_get_drvdata(pdev) };
+ let ptr = unsafe { bindings::pci_get_drvdata(pdev) }.cast();
// SAFETY: `remove_callback` is only ever called after a successful call to
// `probe_callback`, hence it's guaranteed that `ptr` points to a valid and initialized
diff --git a/rust/kernel/platform.rs b/rust/kernel/platform.rs
index 4917cb34e2fe..fd4a494f30e8 100644
--- a/rust/kernel/platform.rs
+++ b/rust/kernel/platform.rs
@@ -80,7 +80,7 @@ impl<T: Driver + 'static> Adapter<T> {
extern "C" fn remove_callback(pdev: *mut bindings::platform_device) {
// SAFETY: `pdev` is a valid pointer to a `struct platform_device`.
- let ptr = unsafe { bindings::platform_get_drvdata(pdev) };
+ let ptr = unsafe { bindings::platform_get_drvdata(pdev) }.cast();
// SAFETY: `remove_callback` is only ever called after a successful call to
// `probe_callback`, hence it's guaranteed that `ptr` points to a valid and initialized
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index 350c380bb8d4..356eef3afdae 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -140,9 +140,10 @@ pub struct Arc<T: ?Sized> {
_p: PhantomData<ArcInner<T>>,
}
+#[doc(hidden)]
#[pin_data]
#[repr(C)]
-struct ArcInner<T: ?Sized> {
+pub struct ArcInner<T: ?Sized> {
refcount: Opaque<bindings::refcount_t>,
data: T,
}
@@ -371,18 +372,20 @@ impl<T: ?Sized> Arc<T> {
}
}
-impl<T: 'static> ForeignOwnable for Arc<T> {
+// SAFETY: The `into_foreign` function returns a pointer that is well-aligned.
+unsafe impl<T: 'static> ForeignOwnable for Arc<T> {
+ type PointedTo = ArcInner<T>;
type Borrowed<'a> = ArcBorrow<'a, T>;
type BorrowedMut<'a> = Self::Borrowed<'a>;
- fn into_foreign(self) -> *mut crate::ffi::c_void {
- ManuallyDrop::new(self).ptr.as_ptr().cast()
+ fn into_foreign(self) -> *mut Self::PointedTo {
+ ManuallyDrop::new(self).ptr.as_ptr()
}
- unsafe fn from_foreign(ptr: *mut crate::ffi::c_void) -> Self {
+ unsafe fn from_foreign(ptr: *mut Self::PointedTo) -> Self {
// SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
// call to `Self::into_foreign`.
- let inner = unsafe { NonNull::new_unchecked(ptr.cast::<ArcInner<T>>()) };
+ let inner = unsafe { NonNull::new_unchecked(ptr) };
// SAFETY: By the safety requirement of this function, we know that `ptr` came from
// a previous call to `Arc::into_foreign`, which guarantees that `ptr` is valid and
@@ -390,17 +393,17 @@ impl<T: 'static> ForeignOwnable for Arc<T> {
unsafe { Self::from_inner(inner) }
}
- unsafe fn borrow<'a>(ptr: *mut crate::ffi::c_void) -> ArcBorrow<'a, T> {
+ unsafe fn borrow<'a>(ptr: *mut Self::PointedTo) -> ArcBorrow<'a, T> {
// SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
// call to `Self::into_foreign`.
- let inner = unsafe { NonNull::new_unchecked(ptr.cast::<ArcInner<T>>()) };
+ let inner = unsafe { NonNull::new_unchecked(ptr) };
// SAFETY: The safety requirements of `from_foreign` ensure that the object remains alive
// for the lifetime of the returned value.
unsafe { ArcBorrow::new(inner) }
}
- unsafe fn borrow_mut<'a>(ptr: *mut crate::ffi::c_void) -> ArcBorrow<'a, T> {
+ unsafe fn borrow_mut<'a>(ptr: *mut Self::PointedTo) -> ArcBorrow<'a, T> {
// SAFETY: The safety requirements for `borrow_mut` are a superset of the safety
// requirements for `borrow`.
unsafe { Self::borrow(ptr) }
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index 9d0471afc964..86562e738eac 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -18,7 +18,19 @@ use pin_init::{PinInit, Zeroable};
///
/// This trait is meant to be used in cases when Rust objects are stored in C objects and
/// eventually "freed" back to Rust.
-pub trait ForeignOwnable: Sized {
+///
+/// # Safety
+///
+/// Implementers must ensure that [`into_foreign`] returns a pointer which meets the alignment
+/// requirements of [`PointedTo`].
+///
+/// [`into_foreign`]: Self::into_foreign
+/// [`PointedTo`]: Self::PointedTo
+pub unsafe trait ForeignOwnable: Sized {
+ /// Type used when the value is foreign-owned. In practical terms only defines the alignment of
+ /// the pointer.
+ type PointedTo;
+
/// Type used to immutably borrow a value that is currently foreign-owned.
type Borrowed<'a>;
@@ -27,16 +39,18 @@ pub trait ForeignOwnable: Sized {
/// Converts a Rust-owned object to a foreign-owned one.
///
- /// The foreign representation is a pointer to void. There are no guarantees for this pointer.
- /// For example, it might be invalid, dangling or pointing to uninitialized memory. Using it in
- /// any way except for [`from_foreign`], [`try_from_foreign`], [`borrow`], or [`borrow_mut`] can
- /// result in undefined behavior.
+ /// # Guarantees
+ ///
+ /// The return value is guaranteed to be well-aligned, but there are no other guarantees for
+ /// this pointer. For example, it might be null, dangling, or point to uninitialized memory.
+ /// Using it in any way except for [`ForeignOwnable::from_foreign`], [`ForeignOwnable::borrow`],
+ /// [`ForeignOwnable::try_from_foreign`] can result in undefined behavior.
///
/// [`from_foreign`]: Self::from_foreign
/// [`try_from_foreign`]: Self::try_from_foreign
/// [`borrow`]: Self::borrow
/// [`borrow_mut`]: Self::borrow_mut
- fn into_foreign(self) -> *mut crate::ffi::c_void;
+ fn into_foreign(self) -> *mut Self::PointedTo;
/// Converts a foreign-owned object back to a Rust-owned one.
///
@@ -46,7 +60,7 @@ pub trait ForeignOwnable: Sized {
/// must not be passed to `from_foreign` more than once.
///
/// [`into_foreign`]: Self::into_foreign
- unsafe fn from_foreign(ptr: *mut crate::ffi::c_void) -> Self;
+ unsafe fn from_foreign(ptr: *mut Self::PointedTo) -> Self;
/// Tries to convert a foreign-owned object back to a Rust-owned one.
///
@@ -58,7 +72,7 @@ pub trait ForeignOwnable: Sized {
/// `ptr` must either be null or satisfy the safety requirements for [`from_foreign`].
///
/// [`from_foreign`]: Self::from_foreign
- unsafe fn try_from_foreign(ptr: *mut crate::ffi::c_void) -> Option<Self> {
+ unsafe fn try_from_foreign(ptr: *mut Self::PointedTo) -> Option<Self> {
if ptr.is_null() {
None
} else {
@@ -81,7 +95,7 @@ pub trait ForeignOwnable: Sized {
///
/// [`into_foreign`]: Self::into_foreign
/// [`from_foreign`]: Self::from_foreign
- unsafe fn borrow<'a>(ptr: *mut crate::ffi::c_void) -> Self::Borrowed<'a>;
+ unsafe fn borrow<'a>(ptr: *mut Self::PointedTo) -> Self::Borrowed<'a>;
/// Borrows a foreign-owned object mutably.
///
@@ -109,21 +123,23 @@ pub trait ForeignOwnable: Sized {
/// [`from_foreign`]: Self::from_foreign
/// [`borrow`]: Self::borrow
/// [`Arc`]: crate::sync::Arc
- unsafe fn borrow_mut<'a>(ptr: *mut crate::ffi::c_void) -> Self::BorrowedMut<'a>;
+ unsafe fn borrow_mut<'a>(ptr: *mut Self::PointedTo) -> Self::BorrowedMut<'a>;
}
-impl ForeignOwnable for () {
+// SAFETY: The `into_foreign` function returns a pointer that is dangling, but well-aligned.
+unsafe impl ForeignOwnable for () {
+ type PointedTo = ();
type Borrowed<'a> = ();
type BorrowedMut<'a> = ();
- fn into_foreign(self) -> *mut crate::ffi::c_void {
+ fn into_foreign(self) -> *mut Self::PointedTo {
core::ptr::NonNull::dangling().as_ptr()
}
- unsafe fn from_foreign(_: *mut crate::ffi::c_void) -> Self {}
+ unsafe fn from_foreign(_: *mut Self::PointedTo) -> Self {}
- unsafe fn borrow<'a>(_: *mut crate::ffi::c_void) -> Self::Borrowed<'a> {}
- unsafe fn borrow_mut<'a>(_: *mut crate::ffi::c_void) -> Self::BorrowedMut<'a> {}
+ unsafe fn borrow<'a>(_: *mut Self::PointedTo) -> Self::Borrowed<'a> {}
+ unsafe fn borrow_mut<'a>(_: *mut Self::PointedTo) -> Self::BorrowedMut<'a> {}
}
/// Runs a cleanup function/closure when dropped.
diff --git a/rust/kernel/xarray.rs b/rust/kernel/xarray.rs
new file mode 100644
index 000000000000..75719e7bb491
--- /dev/null
+++ b/rust/kernel/xarray.rs
@@ -0,0 +1,275 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! XArray abstraction.
+//!
+//! C header: [`include/linux/xarray.h`](srctree/include/linux/xarray.h)
+
+use crate::{
+ alloc, bindings, build_assert,
+ error::{Error, Result},
+ types::{ForeignOwnable, NotThreadSafe, Opaque},
+};
+use core::{iter, marker::PhantomData, mem, pin::Pin, ptr::NonNull};
+use pin_init::{pin_data, pin_init, pinned_drop, PinInit};
+
+/// An array which efficiently maps sparse integer indices to owned objects.
+///
+/// This is similar to a [`crate::alloc::kvec::Vec<Option<T>>`], but more efficient when there are
+/// holes in the index space, and can be efficiently grown.
+///
+/// # Invariants
+///
+/// `self.xa` is always an initialized and valid [`bindings::xarray`] whose entries are either
+/// `XA_ZERO_ENTRY` or came from `T::into_foreign`.
+///
+/// # Examples
+///
+/// ```rust
+/// use kernel::alloc::KBox;
+/// use kernel::xarray::{AllocKind, XArray};
+///
+/// let xa = KBox::pin_init(XArray::new(AllocKind::Alloc1), GFP_KERNEL)?;
+///
+/// let dead = KBox::new(0xdead, GFP_KERNEL)?;
+/// let beef = KBox::new(0xbeef, GFP_KERNEL)?;
+///
+/// let mut guard = xa.lock();
+///
+/// assert_eq!(guard.get(0), None);
+///
+/// assert_eq!(guard.store(0, dead, GFP_KERNEL)?.as_deref(), None);
+/// assert_eq!(guard.get(0).copied(), Some(0xdead));
+///
+/// *guard.get_mut(0).unwrap() = 0xffff;
+/// assert_eq!(guard.get(0).copied(), Some(0xffff));
+///
+/// assert_eq!(guard.store(0, beef, GFP_KERNEL)?.as_deref().copied(), Some(0xffff));
+/// assert_eq!(guard.get(0).copied(), Some(0xbeef));
+///
+/// guard.remove(0);
+/// assert_eq!(guard.get(0), None);
+///
+/// # Ok::<(), Error>(())
+/// ```
+#[pin_data(PinnedDrop)]
+pub struct XArray<T: ForeignOwnable> {
+ #[pin]
+ xa: Opaque<bindings::xarray>,
+ _p: PhantomData<T>,
+}
+
+#[pinned_drop]
+impl<T: ForeignOwnable> PinnedDrop for XArray<T> {
+ fn drop(self: Pin<&mut Self>) {
+ self.iter().for_each(|ptr| {
+ let ptr = ptr.as_ptr();
+ // SAFETY: `ptr` came from `T::into_foreign`.
+ //
+ // INVARIANT: we own the only reference to the array which is being dropped so the
+ // broken invariant is not observable on function exit.
+ drop(unsafe { T::from_foreign(ptr) })
+ });
+
+ // SAFETY: `self.xa` is always valid by the type invariant.
+ unsafe { bindings::xa_destroy(self.xa.get()) };
+ }
+}
+
+/// Flags passed to [`XArray::new`] to configure the array's allocation tracking behavior.
+pub enum AllocKind {
+ /// Consider the first element to be at index 0.
+ Alloc,
+ /// Consider the first element to be at index 1.
+ Alloc1,
+}
+
+impl<T: ForeignOwnable> XArray<T> {
+ /// Creates a new initializer for this type.
+ pub fn new(kind: AllocKind) -> impl PinInit<Self> {
+ let flags = match kind {
+ AllocKind::Alloc => bindings::XA_FLAGS_ALLOC,
+ AllocKind::Alloc1 => bindings::XA_FLAGS_ALLOC1,
+ };
+ pin_init!(Self {
+ // SAFETY: `xa` is valid while the closure is called.
+ //
+ // INVARIANT: `xa` is initialized here to an empty, valid [`bindings::xarray`].
+ xa <- Opaque::ffi_init(|xa| unsafe {
+ bindings::xa_init_flags(xa, flags)
+ }),
+ _p: PhantomData,
+ })
+ }
+
+ fn iter(&self) -> impl Iterator<Item = NonNull<T::PointedTo>> + '_ {
+ let mut index = 0;
+
+ // SAFETY: `self.xa` is always valid by the type invariant.
+ iter::once(unsafe {
+ bindings::xa_find(self.xa.get(), &mut index, usize::MAX, bindings::XA_PRESENT)
+ })
+ .chain(iter::from_fn(move || {
+ // SAFETY: `self.xa` is always valid by the type invariant.
+ Some(unsafe {
+ bindings::xa_find_after(self.xa.get(), &mut index, usize::MAX, bindings::XA_PRESENT)
+ })
+ }))
+ .map_while(|ptr| NonNull::new(ptr.cast()))
+ }
+
+ /// Attempts to lock the [`XArray`] for exclusive access.
+ pub fn try_lock(&self) -> Option<Guard<'_, T>> {
+ // SAFETY: `self.xa` is always valid by the type invariant.
+ if (unsafe { bindings::xa_trylock(self.xa.get()) } != 0) {
+ Some(Guard {
+ xa: self,
+ _not_send: NotThreadSafe,
+ })
+ } else {
+ None
+ }
+ }
+
+ /// Locks the [`XArray`] for exclusive access.
+ pub fn lock(&self) -> Guard<'_, T> {
+ // SAFETY: `self.xa` is always valid by the type invariant.
+ unsafe { bindings::xa_lock(self.xa.get()) };
+
+ Guard {
+ xa: self,
+ _not_send: NotThreadSafe,
+ }
+ }
+}
+
+/// A lock guard.
+///
+/// The lock is unlocked when the guard goes out of scope.
+#[must_use = "the lock unlocks immediately when the guard is unused"]
+pub struct Guard<'a, T: ForeignOwnable> {
+ xa: &'a XArray<T>,
+ _not_send: NotThreadSafe,
+}
+
+impl<T: ForeignOwnable> Drop for Guard<'_, T> {
+ fn drop(&mut self) {
+ // SAFETY:
+ // - `self.xa.xa` is always valid by the type invariant.
+ // - The caller holds the lock, so it is safe to unlock it.
+ unsafe { bindings::xa_unlock(self.xa.xa.get()) };
+ }
+}
+
+/// The error returned by [`store`](Guard::store).
+///
+/// Contains the underlying error and the value that was not stored.
+pub struct StoreError<T> {
+ /// The error that occurred.
+ pub error: Error,
+ /// The value that was not stored.
+ pub value: T,
+}
+
+impl<T> From<StoreError<T>> for Error {
+ fn from(value: StoreError<T>) -> Self {
+ value.error
+ }
+}
+
+impl<'a, T: ForeignOwnable> Guard<'a, T> {
+ fn load<F, U>(&self, index: usize, f: F) -> Option<U>
+ where
+ F: FnOnce(NonNull<T::PointedTo>) -> U,
+ {
+ // SAFETY: `self.xa.xa` is always valid by the type invariant.
+ let ptr = unsafe { bindings::xa_load(self.xa.xa.get(), index) };
+ let ptr = NonNull::new(ptr.cast())?;
+ Some(f(ptr))
+ }
+
+ /// Provides a reference to the element at the given index.
+ pub fn get(&self, index: usize) -> Option<T::Borrowed<'_>> {
+ self.load(index, |ptr| {
+ // SAFETY: `ptr` came from `T::into_foreign`.
+ unsafe { T::borrow(ptr.as_ptr()) }
+ })
+ }
+
+ /// Provides a mutable reference to the element at the given index.
+ pub fn get_mut(&mut self, index: usize) -> Option<T::BorrowedMut<'_>> {
+ self.load(index, |ptr| {
+ // SAFETY: `ptr` came from `T::into_foreign`.
+ unsafe { T::borrow_mut(ptr.as_ptr()) }
+ })
+ }
+
+ /// Removes and returns the element at the given index.
+ pub fn remove(&mut self, index: usize) -> Option<T> {
+ // SAFETY:
+ // - `self.xa.xa` is always valid by the type invariant.
+ // - The caller holds the lock.
+ let ptr = unsafe { bindings::__xa_erase(self.xa.xa.get(), index) }.cast();
+ // SAFETY:
+ // - `ptr` is either NULL or came from `T::into_foreign`.
+ // - `&mut self` guarantees that the lifetimes of [`T::Borrowed`] and [`T::BorrowedMut`]
+ // borrowed from `self` have ended.
+ unsafe { T::try_from_foreign(ptr) }
+ }
+
+ /// Stores an element at the given index.
+ ///
+ /// May drop the lock if needed to allocate memory, and then reacquire it afterwards.
+ ///
+ /// On success, returns the element which was previously at the given index.
+ ///
+ /// On failure, returns the element which was attempted to be stored.
+ pub fn store(
+ &mut self,
+ index: usize,
+ value: T,
+ gfp: alloc::Flags,
+ ) -> Result<Option<T>, StoreError<T>> {
+ build_assert!(
+ mem::align_of::<T::PointedTo>() >= 4,
+ "pointers stored in XArray must be 4-byte aligned"
+ );
+ let new = value.into_foreign();
+
+ let old = {
+ let new = new.cast();
+ // SAFETY:
+ // - `self.xa.xa` is always valid by the type invariant.
+ // - The caller holds the lock.
+ //
+ // INVARIANT: `new` came from `T::into_foreign`.
+ unsafe { bindings::__xa_store(self.xa.xa.get(), index, new, gfp.as_raw()) }
+ };
+
+ // SAFETY: `__xa_store` returns the old entry at this index on success or `xa_err` if an
+ // error happened.
+ let errno = unsafe { bindings::xa_err(old) };
+ if errno != 0 {
+ // SAFETY: `new` came from `T::into_foreign` and `__xa_store` does not take
+ // ownership of the value on error.
+ let value = unsafe { T::from_foreign(new) };
+ Err(StoreError {
+ value,
+ error: Error::from_errno(errno),
+ })
+ } else {
+ let old = old.cast();
+ // SAFETY: `ptr` is either NULL or came from `T::into_foreign`.
+ //
+ // NB: `XA_ZERO_ENTRY` is never returned by functions belonging to the Normal XArray
+ // API; such entries present as `NULL`.
+ Ok(unsafe { T::try_from_foreign(old) })
+ }
+ }
+}
+
+// SAFETY: `XArray<T>` has no shared mutable state so it is `Send` iff `T` is `Send`.
+unsafe impl<T: ForeignOwnable + Send> Send for XArray<T> {}
+
+// SAFETY: `XArray<T>` serialises the interior mutability it provides so it is `Sync` iff `T` is
+// `Send`.
+unsafe impl<T: ForeignOwnable + Send> Sync for XArray<T> {}
generated by cgit v1.2.3 (git 2.39.0) at 2025-08-08 00:10:49 +0300