rbtree v4

rust/helpers.c

@@ -157,6 +157,13 @@ void rust_helper_init_work_with_key(struct work_struct *work, work_func_t func,
 }
 EXPORT_SYMBOL_GPL(rust_helper_init_work_with_key);
 
+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);
+}
+EXPORT_SYMBOL_GPL(rust_helper_rb_link_node);
+
 /*
  * `bindgen` binds the C `size_t` type as the Rust `usize` type, so we can
  * use it in contexts where Rust expects a `usize` like slice (array) indices.

rust/kernel/alloc/box_ext.rs

@@ -4,7 +4,7 @@
 
 use super::{AllocError, Flags};
 use alloc::boxed::Box;
-use core::mem::MaybeUninit;
+use core::{mem::MaybeUninit, ptr};
 
 /// Extensions to [`Box`].
 pub trait BoxExt<T>: Sized {
@@ -17,6 +17,20 @@ pub trait BoxExt<T>: Sized {
     ///
     /// The allocation may fail, in which case an error is returned.
     fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError>;
+
+    /// Drops the contents, but keeps the allocation.
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// use kernel::alloc::flags;
+    ///
+    /// let value = Box::new([0; 32], flags::GFP_KERNEL);
+    /// let value = value.unwrap().drop_contents();
+    /// // Now we can re-use `value`:
+    /// Box::write(value, [1; 32]);
+    /// ```
+    fn drop_contents(self) -> Box<MaybeUninit<T>>;
 }
 
 impl<T> BoxExt<T> for Box<T> {
@@ -53,4 +67,12 @@ impl<T> BoxExt<T> for Box<T> {
         // zero-sized types, we use `NonNull::dangling`.
         Ok(unsafe { Box::from_raw(ptr) })
     }
+
+    fn drop_contents(self) -> Box<MaybeUninit<T>> {
+        let ptr = Box::into_raw(self);
+        // SAFETY: `ptr` is valid, because it came from `Box::into_raw`.
+        unsafe { ptr::drop_in_place(ptr) };
+        // SAFETY: `ptr` is valid, because it came from `Box::into_raw`.
+        unsafe { Box::from_raw(ptr.cast()) }
+    }
 }

rust/kernel/lib.rs

@@ -37,6 +37,7 @@ pub mod kunit;
 pub mod net;
 pub mod prelude;
 pub mod print;
+pub mod rbtree;
 mod static_assert;
 #[doc(hidden)]
 pub mod std_vendor;