On Wed, Mar 26, 2025 at 06:13:46PM +0100, Remo Senekowitsch wrote: > This patch is basically a proof of concept intendend to gather feedback > about how to do this properly. Normally I would want to use the crate > from crates.io[1], but that's not an option in the kernel. We could also > vendor the entire source code of arrayvec. I'm not sure if people will > be happy with that. Do we really need this? The only user in this series I could spot was property_get_reference_args(). And I think that with a proper abstraction of struct fwnode_reference_args we could avoid to copy memory at all. If it turns out we actually need something like this, I'd prefer to move it to rust/kernel/alloc/ and see if it's worth to derive a common trait that maybe can share a few things between ArrayVec and Vec. > > [1] https://crates.io/crates/arrayvec > > Signed-off-by: Remo Senekowitsch <remo@xxxxxxxxxxx> > --- > rust/kernel/arrayvec.rs | 81 +++++++++++++++++++++++++++++++++++++++++ > rust/kernel/lib.rs | 1 + > 2 files changed, 82 insertions(+) > create mode 100644 rust/kernel/arrayvec.rs > > diff --git a/rust/kernel/arrayvec.rs b/rust/kernel/arrayvec.rs > new file mode 100644 > index 000000000..041e7dcce > --- /dev/null > +++ b/rust/kernel/arrayvec.rs > @@ -0,0 +1,81 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +//! Provides [ArrayVec], a stack-allocated vector with static capacity. > + > +use core::mem::MaybeUninit; > + > +/// A stack-allocated vector with statically fixed capacity. > +/// > +/// This can be useful to avoid heap allocation and still ensure safety where a > +/// small but dynamic number of elements is needed. > +/// > +/// For example, consider a function that returns a variable number of values, > +/// but no more than 8. In C, one might achieve this by passing a pointer to > +/// a stack-allocated array as an out-parameter and making the function return > +/// the actual number of elements. This is not safe, because nothing prevents > +/// the caller from reading elements from the array that weren't actually > +/// initialized by the function. `ArrayVec` solves this problem, users are > +/// prevented from accessing uninitialized elements. > +/// > +/// This basically exists already (in a much more mature form) on crates.io: > +/// <https://crates.io/crates/arrayvec> > +#[derive(Debug)] > +pub struct ArrayVec<const N: usize, T> { > + array: [core::mem::MaybeUninit<T>; N], > + len: usize, > +} > + > +impl<const N: usize, T> ArrayVec<N, T> { > + /// Adds a new element to the end of the vector. > + /// > + /// # Panics > + /// > + /// Panics if the vector is already full. > + pub fn push(&mut self, elem: T) { > + if self.len == N { > + panic!("OOM") Please do not panic, this should return a Result instead.
