From: Wedson Almeida Filho <[email protected]>
Add mutable Iterator implementation (`RBTreeIteratorMut`) for `RBTree`,
allowing iteration over (key, value) pairs in key order. Only values are
mutable, as mutating keys implies modifying a node's position in the tree.
Mutable iteration is used by the binder driver during shutdown to
clean up the tree maintained by the "range allocator" [1].
Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [1]
Signed-off-by: Wedson Almeida Filho <[email protected]>
Signed-off-by: Matt Gilbride <[email protected]>
Reviewed-by: Alice Ryhl <[email protected]>
Tested-by: Alice Ryhl <[email protected]>
---
rust/kernel/rbtree.rs | 61 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 61 insertions(+)
diff --git a/rust/kernel/rbtree.rs b/rust/kernel/rbtree.rs
index b1faac831cfc..ccf74e0dc3ec 100644
--- a/rust/kernel/rbtree.rs
+++ b/rust/kernel/rbtree.rs
@@ -222,6 +222,15 @@ pub fn iter(&self) -> RBTreeIterator<'_, K, V> {
}
}
+ /// Returns a mutable iterator over the tree nodes, sorted by key.
+ pub fn iter_mut(&mut self) -> RBTreeIteratorMut<'_, K, V> {
+ RBTreeIteratorMut {
+ _tree: PhantomData,
+ // SAFETY: `root` is valid as it's embedded in `self` and we have a valid `self`.
+ next: unsafe { bindings::rb_first(&self.root) },
+ }
+ }
+
/// Returns an iterator over the keys of the nodes in the tree, in sorted order.
pub fn keys(&self) -> impl Iterator<Item = &'_ K> {
self.iter().map(|(k, _)| k)
@@ -231,6 +240,11 @@ pub fn keys(&self) -> impl Iterator<Item = &'_ K> {
pub fn values(&self) -> impl Iterator<Item = &'_ V> {
self.iter().map(|(_, v)| v)
}
+
+ /// Returns a mutable iterator over the values of the nodes in the tree, sorted by key.
+ pub fn values_mut(&mut self) -> impl Iterator<Item = &'_ mut V> {
+ self.iter_mut().map(|(_, v)| v)
+ }
}
impl<K, V> RBTree<K, V>
@@ -439,6 +453,53 @@ fn next(&mut self) -> Option<Self::Item> {
}
}
+impl<'a, K, V> IntoIterator for &'a mut RBTree<K, V> {
+ type Item = (&'a K, &'a mut V);
+ type IntoIter = RBTreeIteratorMut<'a, K, V>;
+
+ fn into_iter(self) -> Self::IntoIter {
+ self.iter_mut()
+ }
+}
+
+/// A mutable iterator over the nodes of a [`RBTree`].
+///
+/// Instances are created by calling [`RBTree::iter_mut`].
+pub struct RBTreeIteratorMut<'a, K, V> {
+ _tree: PhantomData<&'a RBTree<K, V>>,
+ next: *mut bindings::rb_node,
+}
+
+// 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<'a, K: Send, V: Send> Send for RBTreeIteratorMut<'a, K, V> {}
+
+// 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<'a, K: Sync, V: Sync> Sync for RBTreeIteratorMut<'a, K, V> {}
+
+impl<'a, K, V> Iterator for RBTreeIteratorMut<'a, K, V> {
+ type Item = (&'a K, &'a mut V);
+
+ fn next(&mut self) -> Option<Self::Item> {
+ if self.next.is_null() {
+ return None;
+ }
+
+ // SAFETY: All links fields we create are in a `Node<K, V>`.
+ let cur = unsafe { crate::container_of!(self.next, Node<K, V>, links) }.cast_mut();
+
+ // SAFETY: The reference to the tree used to create the iterator outlives the iterator, so
+ // the tree cannot change (except for the value of previous nodes, but those don't affect
+ // the iteration process). By the tree invariant, all nodes are valid.
+ self.next = unsafe { bindings::rb_next(self.next) };
+
+ // SAFETY: By the same reasoning above, it is safe to dereference the node. Additionally,
+ // it is ok to return a reference to members because the iterator must outlive it.
+ Some(unsafe { (&(*cur).key, &mut (*cur).value) })
+ }
+}
+
/// 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
--
2.44.0.rc0.258.g7320e95886-goog
On 2/19/24 12:48, Matt Gilbride wrote:
> From: Wedson Almeida Filho <[email protected]>
>
> Add mutable Iterator implementation (`RBTreeIteratorMut`) for `RBTree`,
> allowing iteration over (key, value) pairs in key order. Only values are
> mutable, as mutating keys implies modifying a node's position in the tree.
>
> Mutable iteration is used by the binder driver during shutdown to
> clean up the tree maintained by the "range allocator" [1].
>
> Link: https://lore.kernel.org/rust-for-linux/[email protected]/ [1]
> Signed-off-by: Wedson Almeida Filho <[email protected]>
> Signed-off-by: Matt Gilbride <[email protected]>
> Reviewed-by: Alice Ryhl <[email protected]>
> Tested-by: Alice Ryhl <[email protected]>
The comments from patch 3 also apply here.
--
Cheers,
Benno