[PATCH v6 4/6] rust: id_pool: do not supply starting capacity

Alice Ryhl
2025-11-25T14:00:01Z

Rust Binder wants to use inline bitmaps whenever possible to avoid
allocations, so introduce a constructor for an IdPool with arbitrary
capacity that stores the bitmap inline.

The existing constructor could be renamed to with_capacity() to match
constructors for other similar types, but it is removed as there is
currently no user for it.

Acked-by: Yury Norov (NVIDIA) <yury.norov@gmail.com>
Reviewed-by: Burak Emir <bqe@google.com>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
rust/kernel/id_pool.rs | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/rust/kernel/id_pool.rs b/rust/kernel/id_pool.rs
index 7968b6c5566bf7022b865b5f59deaf46c96f747d..1adec2c6fdb0b80515f9b64c67218efa864ce580 100644
--- a/rust/kernel/id_pool.rs
+++ b/rust/kernel/id_pool.rs
@@ -93,6 +93,18 @@ pub fn realloc(&self, flags: Flags) -> Result<PoolResizer, AllocError> {
}

impl IdPool {
+ /// Constructs a new [`IdPool`].
+ ///
+ /// The pool will have a capacity of [`NO_ALLOC_MAX_LEN`].
+ ///
+ /// [`NO_ALLOC_MAX_LEN`]: BitmapVec::NO_ALLOC_MAX_LEN
+ #[inline]
+ pub fn new() -> Self {
+ Self {
+ map: BitmapVec::new_inline(),
+ }
+ }
+
/// Constructs a new [`IdPool`] with space for a specific number of bits.
///
/// A capacity below [`MAX_INLINE_LEN`] is adjusted to [`MAX_INLINE_LEN`].
@@ -229,3 +241,10 @@ pub fn release_id(&mut self, id: usize) {
self.map.clear_bit(id);
}
}
+
+impl Default for IdPool {
+ #[inline]
+ fn default() -> Self {
+ Self::new()
+ }
+}

--
2.52.0.460.gd25c4c69ec-goog