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charset="utf-8" From: Wedson Almeida Filho - Add Iterator implementation (`RBTreeIterator`) for `RBTree`, allowing iteration over (key, value) pairs in key order. - Add individual `keys()` and `values()` functions to iterate over keys or values alone. - Update doctests to use iteration instead of explicitly getting items. Iteration is needed by the binder driver to enumerate all values in a tree for oneway spam detection [1]. Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-17-08ba9197f637@google.com/ [1] Signed-off-by: Wedson Almeida Filho Reviewed-by: Alice Ryhl Tested-by: Alice Ryhl Signed-off-by: Matt Gilbride --- rust/kernel/rbtree.rs | 129 +++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 111 insertions(+), 18 deletions(-) diff --git a/rust/kernel/rbtree.rs b/rust/kernel/rbtree.rs index ad406fc32d67..2f836be7bdbe 100644 --- a/rust/kernel/rbtree.rs +++ b/rust/kernel/rbtree.rs @@ -54,14 +54,30 @@ struct Node { /// assert_eq!(tree.get(&30).unwrap(), &300); /// } /// +/// // Iterate over the nodes we just inserted. +/// { +/// let mut iter = tree.iter(); +/// assert_eq!(iter.next().unwrap(), (&10, &100)); +/// assert_eq!(iter.next().unwrap(), (&20, &200)); +/// assert_eq!(iter.next().unwrap(), (&30, &300)); +/// assert!(iter.next().is_none()); +/// } +/// +/// // Print all elements. +/// for (key, value) in &tree { +/// pr_info!("{} = {}\n", key, value); +/// } +/// /// // Replace one of the elements. /// tree.try_create_and_insert(10, 1000)?; /// /// // 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); +/// let mut iter = tree.iter(); +/// assert_eq!(iter.next().unwrap(), (&10, &1000)); +/// assert_eq!(iter.next().unwrap(), (&20, &200)); +/// assert_eq!(iter.next().unwrap(), (&30, &300)); +/// assert!(iter.next().is_none()); /// } /// /// // Change the value of one of the elements. @@ -69,9 +85,11 @@ struct Node { /// /// // 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); +/// let mut iter = tree.iter(); +/// assert_eq!(iter.next().unwrap(), (&10, &1000)); +/// assert_eq!(iter.next().unwrap(), (&20, &200)); +/// assert_eq!(iter.next().unwrap(), (&30, &3000)); +/// assert!(iter.next().is_none()); /// } /// /// // Remove an element. @@ -79,9 +97,10 @@ struct Node { /// /// // 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); +/// let mut iter = tree.iter(); +/// assert_eq!(iter.next().unwrap(), (&20, &200)); +/// assert_eq!(iter.next().unwrap(), (&30, &3000)); +/// assert!(iter.next().is_none()); /// } /// /// # Ok::<(), Error>(()) @@ -121,9 +140,11 @@ struct Node { /// /// // 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); +/// let mut iter = tree.iter(); +/// assert_eq!(iter.next().unwrap(), (&10, &100)); +/// assert_eq!(iter.next().unwrap(), (&20, &200)); +/// assert_eq!(iter.next().unwrap(), (&30, &300)); +/// assert!(iter.next().is_none()); /// } /// /// // Remove a node, getting back ownership of it. @@ -131,9 +152,10 @@ struct Node { /// /// // 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); +/// let mut iter = tree.iter(); +/// assert_eq!(iter.next().unwrap(), (&10, &100)); +/// assert_eq!(iter.next().unwrap(), (&20, &200)); +/// assert!(iter.next().is_none()); /// } /// /// // Create a preallocated reservation that we can re-use later. @@ -145,9 +167,11 @@ struct Node { /// /// // 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); +/// let mut iter = tree.iter(); +/// assert_eq!(iter.next().unwrap(), (&10, &100)); +/// assert_eq!(iter.next().unwrap(), (&15, &150)); +/// assert_eq!(iter.next().unwrap(), (&20, &200)); +/// assert!(iter.next().is_none()); /// } /// /// # Ok::<(), Error>(()) @@ -188,6 +212,25 @@ pub fn try_reserve_node() -> Result> { pub fn try_allocate_node(key: K, value: V) -> Result> { Ok(Self::try_reserve_node()?.into_node(key, value)) } + + /// Returns an iterator over the tree nodes, sorted by key. + pub fn iter(&self) -> RBTreeIterator<'_, K, V> { + RBTreeIterator { + _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 { + self.iter().map(|(k, _)| k) + } + + /// Returns an iterator over the values of the nodes in the tree, sorted by key. + pub fn values(&self) -> impl Iterator { + self.iter().map(|(_, v)| v) + } } impl RBTree @@ -373,6 +416,56 @@ fn drop(&mut self) { } } +impl<'a, K, V> IntoIterator for &'a RBTree { + type Item = (&'a K, &'a V); + type IntoIter = RBTreeIterator<'a, K, V>; + + fn into_iter(self) -> Self::IntoIter { + self.iter() + } +} + +/// An iterator over the nodes of a [`RBTree`]. +/// +/// Instances are created by calling [`RBTree::iter`]. +/// +/// # Invariants +/// - `self.next` is a valid pointer. +/// - `self.next` points to a node stored inside of a valid `RBTree`. +pub struct RBTreeIterator<'a, K, V> { + _tree: PhantomData<&'a RBTree>, + next: *mut bindings::rb_node, +} + +// SAFETY: The [`RBTreeIterator`] gives out immutable references to K and V, so it has the same +// thread safety requirements as immutable references. +unsafe impl<'a, K: Sync, V: Sync> Send for RBTreeIterator<'a, K, V> {} + +// SAFETY: The [`RBTreeIterator`] gives out immutable references to K and V, so it has the same +// thread safety requirements as immutable references. +unsafe impl<'a, K: Sync, V: Sync> Sync for RBTreeIterator<'a, K, V> {} + +impl<'a, K, V> Iterator for RBTreeIterator<'a, K, V> { + type Item = (&'a K, &'a V); + + fn next(&mut self) -> Option { + if self.next.is_null() { + return None; + } + + // 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 cur = unsafe { container_of!(self.next, Node, links) }; + + // SAFETY: `self.next` is a valid tree node by the type invariants. + 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, &(*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 -- 2.44.0.769.g3c40516874-goog