Re: [PATCH v4 24/28] rust: alloc: implement `contains` for `Flags`

Alice Ryhl
2024-08-07T13:53:56Z

On Mon, Aug 5, 2024 at 5:22 PM Danilo Krummrich <dakr@kernel.org> wrote:
>
> Provide a simple helper function to check whether given flags do
> contain one or multiple other flags.
>
> This is used by a subsequent patch implementing the Cmalloc `Allocator`
> to check for __GFP_ZERO.
>
> Signed-off-by: Danilo Krummrich <dakr@kernel.org>

One nit, but:

Reviewed-by: Alice Ryhl <aliceryhl@google.com>

> rust/kernel/alloc.rs | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> index 8a1cecc20d09..615afe69d097 100644
> --- a/rust/kernel/alloc.rs
> +++ b/rust/kernel/alloc.rs
> @@ -34,7 +34,7 @@
> /// They can be combined with the operators `|`, `&`, and `!`.
> ///
> /// Values can be used from the [`flags`] module.
> -#[derive(Clone, Copy)]
> +#[derive(Clone, Copy, PartialEq)]
> pub struct Flags(u32);
>
> impl Flags {
> @@ -42,6 +42,11 @@ impl Flags {
> pub(crate) fn as_raw(self) -> u32 {
> self.0
> }
> +
> + /// Check whether `flags` is contained in `self`.
> + pub fn contains(&self, flags: Flags) -> bool {
> + (*self & flags) == flags
> + }

Since this type is Copy, you can do this:

pub fn contains(self, flags: Flags) -> bool {
(self & flags) == flags
}

and avoid the asterisk.

Alice