From 6cd341715558b8422f33509d9b99a1a0a5b4b29c Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Wed, 14 Aug 2024 08:05:21 +0000 Subject: rust: list: add ListArc The `ListArc` type can be thought of as a special reference to a refcounted object that owns the permission to manipulate the `next`/`prev` pointers stored in the refcounted object. By ensuring that each object has only one `ListArc` reference, the owner of that reference is assured exclusive access to the `next`/`prev` pointers. When a `ListArc` is inserted into a `List`, the `List` takes ownership of the `ListArc` reference. There are various strategies for ensuring that a value has only one `ListArc` reference. The simplest is to convert a `UniqueArc` into a `ListArc`. However, the refcounted object could also keep track of whether a `ListArc` exists using a boolean, which could allow for the creation of new `ListArc` references from an `Arc` reference. Whatever strategy is used, the relevant tracking is referred to as "the tracking inside `T`", and the `ListArcSafe` trait (and its subtraits) are used to update the tracking when a `ListArc` is created or destroyed. Note that we allow the case where the tracking inside `T` thinks that a `ListArc` exists, but actually, there isn't a `ListArc`. However, we do not allow the opposite situation where a `ListArc` exists, but the tracking thinks it doesn't. This is because the former can at most result in us failing to create a `ListArc` when the operation could succeed, whereas the latter can result in the creation of two `ListArc` references. Only the latter situation can lead to memory safety issues. This patch introduces the `impl_list_arc_safe!` macro that allows you to implement `ListArcSafe` for types using the strategy where a `ListArc` can only be created from a `UniqueArc`. Other strategies are introduced in later patches. This is part of the linked list that Rust Binder will use for many different things. The strategy where a `ListArc` can only be created from a `UniqueArc` is actually sufficient for most of the objects that Rust Binder needs to insert into linked lists. Usually, these are todo items that are created and then immediately inserted into a queue. The const generic ID allows objects to have several prev/next pointer pairs so that the same object can be inserted into several different lists. You are able to have several `ListArc` references as long as they correspond to different pointer pairs. The ID itself is purely a compile-time concept and will not be present in the final binary. Both the `List` and the `ListArc` will need to agree on the ID for them to work together. Rust Binder uses this in a few places (e.g. death recipients) where the same object can be inserted into both generic todo lists and some other lists for tracking the status of the object. The ID is a const generic rather than a type parameter because the `pair_from_unique` method needs to be able to assert that the two ids are different. There's no easy way to assert that when using types instead of integers. Reviewed-by: Benno Lossin Signed-off-by: Alice Ryhl Link: https://lore.kernel.org/r/20240814-linked-list-v5-2-f5f5e8075da0@google.com Signed-off-by: Miguel Ojeda --- rust/kernel/lib.rs | 1 + 1 file changed, 1 insertion(+) (limited to 'rust/kernel/lib.rs') diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 274bdc1b0a82..9baea9e9ee1a 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -38,6 +38,7 @@ pub mod init; pub mod ioctl; #[cfg(CONFIG_KUNIT)] pub mod kunit; +pub mod list; #[cfg(CONFIG_NET)] pub mod net; pub mod page; -- cgit v1.2.3 From 4d080a029db1b2ff7e173d86886b3429596f3c63 Mon Sep 17 00:00:00 2001 From: FUJITA Tomonori Date: Wed, 28 Aug 2024 07:35:11 +0000 Subject: rust: sizes: add commonly used constants Add rust equivalent to include/linux/sizes.h, makes code more readable. Only SZ_*K that QT2025 PHY driver uses are added. Make generated constants accessible with a proper type. Reviewed-by: Alice Ryhl Reviewed-by: Andrew Lunn Reviewed-by: Benno Lossin Reviewed-by: Trevor Gross Signed-off-by: FUJITA Tomonori Signed-off-by: David S. Miller --- rust/kernel/lib.rs | 1 + rust/kernel/sizes.rs | 26 ++++++++++++++++++++++++++ 2 files changed, 27 insertions(+) create mode 100644 rust/kernel/sizes.rs (limited to 'rust/kernel/lib.rs') diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 274bdc1b0a82..58ed400198bf 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -43,6 +43,7 @@ pub mod net; pub mod page; pub mod prelude; pub mod print; +pub mod sizes; mod static_assert; #[doc(hidden)] pub mod std_vendor; diff --git a/rust/kernel/sizes.rs b/rust/kernel/sizes.rs new file mode 100644 index 000000000000..834c343e4170 --- /dev/null +++ b/rust/kernel/sizes.rs @@ -0,0 +1,26 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Commonly used sizes. +//! +//! C headers: [`include/linux/sizes.h`](srctree/include/linux/sizes.h). + +/// 0x00000400 +pub const SZ_1K: usize = bindings::SZ_1K as usize; +/// 0x00000800 +pub const SZ_2K: usize = bindings::SZ_2K as usize; +/// 0x00001000 +pub const SZ_4K: usize = bindings::SZ_4K as usize; +/// 0x00002000 +pub const SZ_8K: usize = bindings::SZ_8K as usize; +/// 0x00004000 +pub const SZ_16K: usize = bindings::SZ_16K as usize; +/// 0x00008000 +pub const SZ_32K: usize = bindings::SZ_32K as usize; +/// 0x00010000 +pub const SZ_64K: usize = bindings::SZ_64K as usize; +/// 0x00020000 +pub const SZ_128K: usize = bindings::SZ_128K as usize; +/// 0x00040000 +pub const SZ_256K: usize = bindings::SZ_256K as usize; +/// 0x00080000 +pub const SZ_512K: usize = bindings::SZ_512K as usize; -- cgit v1.2.3 From a0d13aac7022f95ec161c18d18e3d81172666ed8 Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Thu, 22 Aug 2024 16:37:53 +0000 Subject: rust: rbtree: add red-black tree implementation backed by the C version The rust rbtree exposes a map-like interface over keys and values, backed by the kernel red-black tree implementation. Values can be inserted, deleted, and retrieved from a `RBTree` by key. This base abstraction is used by binder to store key/value pairs and perform lookups, for example the patch "[PATCH RFC 03/20] rust_binder: add threading support" in the binder RFC [1]. Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-3-08ba9197f637@google.com/ [1] Signed-off-by: Wedson Almeida Filho Reviewed-by: Alice Ryhl Tested-by: Alice Ryhl Reviewed-by: Boqun Feng Reviewed-by: Benno Lossin Signed-off-by: Matt Gilbride Link: https://lore.kernel.org/r/20240822-b4-rbtree-v12-1-014561758a57@google.com [ Updated link to docs.kernel.org. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/helpers/helpers.c | 1 + rust/helpers/rbtree.c | 9 ++ rust/kernel/lib.rs | 1 + rust/kernel/rbtree.rs | 432 +++++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 443 insertions(+) create mode 100644 rust/helpers/rbtree.c create mode 100644 rust/kernel/rbtree.rs (limited to 'rust/kernel/lib.rs') diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c index 173533616c91..30f40149f3a9 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -15,6 +15,7 @@ #include "kunit.c" #include "mutex.c" #include "page.c" +#include "rbtree.c" #include "refcount.c" #include "signal.c" #include "slab.c" diff --git a/rust/helpers/rbtree.c b/rust/helpers/rbtree.c new file mode 100644 index 000000000000..6d404b84a9b5 --- /dev/null +++ b/rust/helpers/rbtree.c @@ -0,0 +1,9 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include + +void rust_helper_rb_link_node(struct rb_node *node, struct rb_node *parent, + struct rb_node **rb_link) +{ + rb_link_node(node, parent, rb_link); +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 9baea9e9ee1a..f10b06a78b9d 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -44,6 +44,7 @@ pub mod net; pub mod page; pub mod prelude; pub mod print; +pub mod rbtree; mod static_assert; #[doc(hidden)] pub mod std_vendor; diff --git a/rust/kernel/rbtree.rs b/rust/kernel/rbtree.rs new file mode 100644 index 000000000000..cf25437c795f --- /dev/null +++ b/rust/kernel/rbtree.rs @@ -0,0 +1,432 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Red-black trees. +//! +//! C header: [`include/linux/rbtree.h`](srctree/include/linux/rbtree.h) +//! +//! Reference: + +use crate::{alloc::Flags, bindings, container_of, error::Result, prelude::*}; +use alloc::boxed::Box; +use core::{ + cmp::{Ord, Ordering}, + marker::PhantomData, + mem::MaybeUninit, + ptr::{addr_of_mut, NonNull}, +}; + +/// A red-black tree with owned nodes. +/// +/// It is backed by the kernel C red-black trees. +/// +/// # Examples +/// +/// In the example below we do several operations on a tree. We note that insertions may fail if +/// the system is out of memory. +/// +/// ``` +/// use kernel::{alloc::flags, rbtree::{RBTree, RBTreeNode, RBTreeNodeReservation}}; +/// +/// // Create a new tree. +/// let mut tree = RBTree::new(); +/// +/// // Insert three elements. +/// tree.try_create_and_insert(20, 200, flags::GFP_KERNEL)?; +/// tree.try_create_and_insert(10, 100, flags::GFP_KERNEL)?; +/// tree.try_create_and_insert(30, 300, flags::GFP_KERNEL)?; +/// +/// // Check the nodes we just inserted. +/// { +/// assert_eq!(tree.get(&10).unwrap(), &100); +/// assert_eq!(tree.get(&20).unwrap(), &200); +/// assert_eq!(tree.get(&30).unwrap(), &300); +/// } +/// +/// // Replace one of the elements. +/// tree.try_create_and_insert(10, 1000, flags::GFP_KERNEL)?; +/// +/// // Check that the tree reflects the replacement. +/// { +/// assert_eq!(tree.get(&10).unwrap(), &1000); +/// assert_eq!(tree.get(&20).unwrap(), &200); +/// assert_eq!(tree.get(&30).unwrap(), &300); +/// } +/// +/// // Change the value of one of the elements. +/// *tree.get_mut(&30).unwrap() = 3000; +/// +/// // Check that the tree reflects the update. +/// { +/// assert_eq!(tree.get(&10).unwrap(), &1000); +/// assert_eq!(tree.get(&20).unwrap(), &200); +/// assert_eq!(tree.get(&30).unwrap(), &3000); +/// } +/// +/// // Remove an element. +/// tree.remove(&10); +/// +/// // Check that the tree reflects the removal. +/// { +/// assert_eq!(tree.get(&10), None); +/// assert_eq!(tree.get(&20).unwrap(), &200); +/// assert_eq!(tree.get(&30).unwrap(), &3000); +/// } +/// +/// # Ok::<(), Error>(()) +/// ``` +/// +/// In the example below, we first allocate a node, acquire a spinlock, then insert the node into +/// the tree. This is useful when the insertion context does not allow sleeping, for example, when +/// holding a spinlock. +/// +/// ``` +/// use kernel::{alloc::flags, rbtree::{RBTree, RBTreeNode}, sync::SpinLock}; +/// +/// fn insert_test(tree: &SpinLock>) -> Result { +/// // Pre-allocate node. This may fail (as it allocates memory). +/// let node = RBTreeNode::new(10, 100, flags::GFP_KERNEL)?; +/// +/// // Insert node while holding the lock. It is guaranteed to succeed with no allocation +/// // attempts. +/// let mut guard = tree.lock(); +/// guard.insert(node); +/// Ok(()) +/// } +/// ``` +/// +/// In the example below, we reuse an existing node allocation from an element we removed. +/// +/// ``` +/// use kernel::{alloc::flags, rbtree::{RBTree, RBTreeNodeReservation}}; +/// +/// // Create a new tree. +/// let mut tree = RBTree::new(); +/// +/// // Insert three elements. +/// tree.try_create_and_insert(20, 200, flags::GFP_KERNEL)?; +/// tree.try_create_and_insert(10, 100, flags::GFP_KERNEL)?; +/// tree.try_create_and_insert(30, 300, flags::GFP_KERNEL)?; +/// +/// // Check the nodes we just inserted. +/// { +/// assert_eq!(tree.get(&10).unwrap(), &100); +/// assert_eq!(tree.get(&20).unwrap(), &200); +/// assert_eq!(tree.get(&30).unwrap(), &300); +/// } +/// +/// // Remove a node, getting back ownership of it. +/// let existing = tree.remove(&30).unwrap(); +/// +/// // Check that the tree reflects the removal. +/// { +/// assert_eq!(tree.get(&10).unwrap(), &100); +/// assert_eq!(tree.get(&20).unwrap(), &200); +/// assert_eq!(tree.get(&30), None); +/// } +/// +/// // Create a preallocated reservation that we can re-use later. +/// let reservation = RBTreeNodeReservation::new(flags::GFP_KERNEL)?; +/// +/// // Insert a new node into the tree, reusing the previous allocation. This is guaranteed to +/// // succeed (no memory allocations). +/// tree.insert(reservation.into_node(15, 150)); +/// +/// // Check that the tree reflect the new insertion. +/// { +/// assert_eq!(tree.get(&10).unwrap(), &100); +/// assert_eq!(tree.get(&15).unwrap(), &150); +/// assert_eq!(tree.get(&20).unwrap(), &200); +/// } +/// +/// # Ok::<(), Error>(()) +/// ``` +/// +/// # Invariants +/// +/// Non-null parent/children pointers stored in instances of the `rb_node` C struct are always +/// valid, and pointing to a field of our internal representation of a node. +pub struct RBTree { + root: bindings::rb_root, + _p: PhantomData>, +} + +// SAFETY: An [`RBTree`] allows the same kinds of access to its values that a struct allows to its +// fields, so we use the same Send condition as would be used for a struct with K and V fields. +unsafe impl Send for RBTree {} + +// SAFETY: An [`RBTree`] allows the same kinds of access to its values that a struct allows to its +// fields, so we use the same Sync condition as would be used for a struct with K and V fields. +unsafe impl Sync for RBTree {} + +impl RBTree { + /// Creates a new and empty tree. + pub fn new() -> Self { + Self { + // INVARIANT: There are no nodes in the tree, so the invariant holds vacuously. + root: bindings::rb_root::default(), + _p: PhantomData, + } + } +} + +impl RBTree +where + K: Ord, +{ + /// Tries to insert a new value into the tree. + /// + /// It overwrites a node if one already exists with the same key and returns it (containing the + /// key/value pair). Returns [`None`] if a node with the same key didn't already exist. + /// + /// Returns an error if it cannot allocate memory for the new node. + pub fn try_create_and_insert( + &mut self, + key: K, + value: V, + flags: Flags, + ) -> Result>> { + Ok(self.insert(RBTreeNode::new(key, value, flags)?)) + } + + /// Inserts a new node into the tree. + /// + /// It overwrites a node if one already exists with the same key and returns it (containing the + /// key/value pair). Returns [`None`] if a node with the same key didn't already exist. + /// + /// This function always succeeds. + pub fn insert(&mut self, RBTreeNode { node }: RBTreeNode) -> Option> { + let node = Box::into_raw(node); + // SAFETY: `node` is valid at least until we call `Box::from_raw`, which only happens when + // the node is removed or replaced. + let node_links = unsafe { addr_of_mut!((*node).links) }; + + // The parameters of `bindings::rb_link_node` are as follows: + // - `node`: A pointer to an uninitialized node being inserted. + // - `parent`: A pointer to an existing node in the tree. One of its child pointers must be + // null, and `node` will become a child of `parent` by replacing that child pointer + // with a pointer to `node`. + // - `rb_link`: A pointer to either the left-child or right-child field of `parent`. This + // specifies which child of `parent` should hold `node` after this call. The + // value of `*rb_link` must be null before the call to `rb_link_node`. If the + // red/black tree is empty, then it’s also possible for `parent` to be null. In + // this case, `rb_link` is a pointer to the `root` field of the red/black tree. + // + // We will traverse the tree looking for a node that has a null pointer as its child, + // representing an empty subtree where we can insert our new node. We need to make sure + // that we preserve the ordering of the nodes in the tree. In each iteration of the loop + // we store `parent` and `child_field_of_parent`, and the new `node` will go somewhere + // in the subtree of `parent` that `child_field_of_parent` points at. Once + // we find an empty subtree, we can insert the new node using `rb_link_node`. + let mut parent = core::ptr::null_mut(); + let mut child_field_of_parent: &mut *mut bindings::rb_node = &mut self.root.rb_node; + while !child_field_of_parent.is_null() { + parent = *child_field_of_parent; + + // We need to determine whether `node` should be the left or right child of `parent`, + // so we will compare with the `key` field of `parent` a.k.a. `this` below. + // + // SAFETY: By the type invariant of `Self`, all non-null `rb_node` pointers stored in `self` + // point to the links field of `Node` objects. + let this = unsafe { container_of!(parent, Node, links) }; + + // SAFETY: `this` is a non-null node so it is valid by the type invariants. `node` is + // valid until the node is removed. + match unsafe { (*node).key.cmp(&(*this).key) } { + // We would like `node` to be the left child of `parent`. Move to this child to check + // whether we can use it, or continue searching, at the next iteration. + // + // SAFETY: `parent` is a non-null node so it is valid by the type invariants. + Ordering::Less => child_field_of_parent = unsafe { &mut (*parent).rb_left }, + // We would like `node` to be the right child of `parent`. Move to this child to check + // whether we can use it, or continue searching, at the next iteration. + // + // SAFETY: `parent` is a non-null node so it is valid by the type invariants. + Ordering::Greater => child_field_of_parent = unsafe { &mut (*parent).rb_right }, + Ordering::Equal => { + // There is an existing node in the tree with this key, and that node is + // `parent`. Thus, we are replacing parent with a new node. + // + // INVARIANT: We are replacing an existing node with a new one, which is valid. + // It remains valid because we "forgot" it with `Box::into_raw`. + // SAFETY: All pointers are non-null and valid. + unsafe { bindings::rb_replace_node(parent, node_links, &mut self.root) }; + + // INVARIANT: The node is being returned and the caller may free it, however, + // it was removed from the tree. So the invariants still hold. + return Some(RBTreeNode { + // SAFETY: `this` was a node in the tree, so it is valid. + node: unsafe { Box::from_raw(this.cast_mut()) }, + }); + } + } + } + + // INVARIANT: We are linking in a new node, which is valid. It remains valid because we + // "forgot" it with `Box::into_raw`. + // SAFETY: All pointers are non-null and valid (`*child_field_of_parent` is null, but `child_field_of_parent` is a + // mutable reference). + unsafe { bindings::rb_link_node(node_links, parent, child_field_of_parent) }; + + // SAFETY: All pointers are valid. `node` has just been inserted into the tree. + unsafe { bindings::rb_insert_color(node_links, &mut self.root) }; + None + } + + /// Returns a node with the given key, if one exists. + fn find(&self, key: &K) -> Option>> { + let mut node = self.root.rb_node; + while !node.is_null() { + // SAFETY: By the type invariant of `Self`, all non-null `rb_node` pointers stored in `self` + // point to the links field of `Node` objects. + let this = unsafe { container_of!(node, Node, links) }; + // SAFETY: `this` is a non-null node so it is valid by the type invariants. + node = match key.cmp(unsafe { &(*this).key }) { + // SAFETY: `node` is a non-null node so it is valid by the type invariants. + Ordering::Less => unsafe { (*node).rb_left }, + // SAFETY: `node` is a non-null node so it is valid by the type invariants. + Ordering::Greater => unsafe { (*node).rb_right }, + Ordering::Equal => return NonNull::new(this.cast_mut()), + } + } + None + } + + /// Returns a reference to the value corresponding to the key. + pub fn get(&self, key: &K) -> Option<&V> { + // SAFETY: The `find` return value is a node in the tree, so it is valid. + self.find(key).map(|node| unsafe { &node.as_ref().value }) + } + + /// Returns a mutable reference to the value corresponding to the key. + pub fn get_mut(&mut self, key: &K) -> Option<&mut V> { + // SAFETY: The `find` return value is a node in the tree, so it is valid. + self.find(key) + .map(|mut node| unsafe { &mut node.as_mut().value }) + } + + /// Removes the node with the given key from the tree. + /// + /// It returns the node that was removed if one exists, or [`None`] otherwise. + fn remove_node(&mut self, key: &K) -> Option> { + let mut node = self.find(key)?; + + // SAFETY: The `find` return value is a node in the tree, so it is valid. + unsafe { bindings::rb_erase(&mut node.as_mut().links, &mut self.root) }; + + // INVARIANT: The node is being returned and the caller may free it, however, it was + // removed from the tree. So the invariants still hold. + Some(RBTreeNode { + // SAFETY: The `find` return value was a node in the tree, so it is valid. + node: unsafe { Box::from_raw(node.as_ptr()) }, + }) + } + + /// Removes the node with the given key from the tree. + /// + /// It returns the value that was removed if one exists, or [`None`] otherwise. + pub fn remove(&mut self, key: &K) -> Option { + self.remove_node(key).map(|node| node.node.value) + } +} + +impl Default for RBTree { + fn default() -> Self { + Self::new() + } +} + +impl Drop for RBTree { + fn drop(&mut self) { + // SAFETY: `root` is valid as it's embedded in `self` and we have a valid `self`. + let mut next = unsafe { bindings::rb_first_postorder(&self.root) }; + + // INVARIANT: The loop invariant is that all tree nodes from `next` in postorder are valid. + while !next.is_null() { + // SAFETY: All links fields we create are in a `Node`. + let this = unsafe { container_of!(next, Node, links) }; + + // Find out what the next node is before disposing of the current one. + // SAFETY: `next` and all nodes in postorder are still valid. + next = unsafe { bindings::rb_next_postorder(next) }; + + // INVARIANT: This is the destructor, so we break the type invariant during clean-up, + // but it is not observable. The loop invariant is still maintained. + + // SAFETY: `this` is valid per the loop invariant. + unsafe { drop(Box::from_raw(this.cast_mut())) }; + } + } +} + +/// A memory reservation for a red-black tree node. +/// +/// +/// It contains the memory needed to hold a node that can be inserted into a red-black tree. One +/// can be obtained by directly allocating it ([`RBTreeNodeReservation::new`]). +pub struct RBTreeNodeReservation { + node: Box>>, +} + +impl RBTreeNodeReservation { + /// Allocates memory for a node to be eventually initialised and inserted into the tree via a + /// call to [`RBTree::insert`]. + pub fn new(flags: Flags) -> Result> { + Ok(RBTreeNodeReservation { + node: as BoxExt<_>>::new_uninit(flags)?, + }) + } +} + +// SAFETY: This doesn't actually contain K or V, and is just a memory allocation. Those can always +// be moved across threads. +unsafe impl Send for RBTreeNodeReservation {} + +// SAFETY: This doesn't actually contain K or V, and is just a memory allocation. +unsafe impl Sync for RBTreeNodeReservation {} + +impl RBTreeNodeReservation { + /// Initialises a node reservation. + /// + /// It then becomes an [`RBTreeNode`] that can be inserted into a tree. + pub fn into_node(self, key: K, value: V) -> RBTreeNode { + let node = Box::write( + self.node, + Node { + key, + value, + links: bindings::rb_node::default(), + }, + ); + RBTreeNode { node } + } +} + +/// A red-black tree node. +/// +/// The node is fully initialised (with key and value) and can be inserted into a tree without any +/// extra allocations or failure paths. +pub struct RBTreeNode { + node: Box>, +} + +impl RBTreeNode { + /// Allocates and initialises a node that can be inserted into the tree via + /// [`RBTree::insert`]. + pub fn new(key: K, value: V, flags: Flags) -> Result> { + Ok(RBTreeNodeReservation::new(flags)?.into_node(key, value)) + } +} + +// SAFETY: If K and V can be sent across threads, then it's also okay to send [`RBTreeNode`] across +// threads. +unsafe impl Send for RBTreeNode {} + +// SAFETY: If K and V can be accessed without synchronization, then it's also okay to access +// [`RBTreeNode`] without synchronization. +unsafe impl Sync for RBTreeNode {} + +struct Node { + links: bindings::rb_node, + key: K, + value: V, +} -- cgit v1.2.3