From 9def0d0a2a1c62d7970f4ce5ad5557968c98f637 Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Fri, 2 May 2025 13:19:31 +0000 Subject: rust: alloc: add Vec::push_within_capacity This introduces a new method called `push_within_capacity` for appending to a vector without attempting to allocate if the capacity is full. Rust Binder will use this in various places to safely push to a vector while holding a spinlock. The implementation is moved to a push_within_capacity_unchecked method. This is preferred over having push() call push_within_capacity() followed by an unwrap_unchecked() for simpler unsafe. Panics in the kernel are best avoided when possible, so an error is returned if the vector does not have sufficient capacity. An error type is used rather than just returning Result<(),T> to make it more convenient for callers (i.e. they can use ? or unwrap). Signed-off-by: Alice Ryhl Reviewed-by: Greg Kroah-Hartman Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20250502-vec-methods-v5-3-06d20ad9366f@google.com [ Remove public visibility from `Vec::push_within_capacity_unchecked()`. - Danilo ] Signed-off-by: Danilo Krummrich --- rust/kernel/alloc/kvec/errors.rs | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) create mode 100644 rust/kernel/alloc/kvec/errors.rs (limited to 'rust/kernel/alloc/kvec/errors.rs') diff --git a/rust/kernel/alloc/kvec/errors.rs b/rust/kernel/alloc/kvec/errors.rs new file mode 100644 index 000000000000..84c96ec5007d --- /dev/null +++ b/rust/kernel/alloc/kvec/errors.rs @@ -0,0 +1,23 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Errors for the [`Vec`] type. + +use core::fmt::{self, Debug, Formatter}; +use kernel::prelude::*; + +/// Error type for [`Vec::push_within_capacity`]. +pub struct PushError(pub T); + +impl Debug for PushError { + fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result { + write!(f, "Not enough capacity") + } +} + +impl From> for Error { + fn from(_: PushError) -> Error { + // Returning ENOMEM isn't appropriate because the system is not out of memory. The vector + // is just full and we are refusing to resize it. + EINVAL + } +} -- cgit v1.2.3