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Date:   Fri, 03 Nov 2023 16:30:54 +0000
To:     Alice Ryhl <aliceryhl@google.com>
From:   Benno Lossin <benno.lossin@proton.me>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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        Todd Kjos <tkjos@android.com>,
        Martijn Coenen <maco@android.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Christian Brauner <brauner@kernel.org>,
        Carlos Llamas <cmllamas@google.com>,
        Suren Baghdasaryan <surenb@google.com>,
        Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org,
        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
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        Matt Gilbride <mattgilbride@google.com>,
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        Matthew Maurer <mmaurer@google.com>
Subject: Re: [PATCH RFC 02/20] rust_binder: add binderfs support to Rust binder
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On 01.11.23 19:01, Alice Ryhl wrote:
> +/// There is one context per binder file (/dev/binder, /dev/hwbinder, et=
c)
> +#[pin_data]
> +pub(crate) struct Context {
> +    #[pin]
> +    manager: Mutex<Manager>,
> +    pub(crate) name: CString,
> +    #[pin]
> +    links: ListLinks,
> +}
> +
> +kernel::list::impl_has_list_links! {
> +    impl HasListLinks<0> for Context { self.links }
> +}
> +kernel::list::impl_list_arc_safe! {
> +    impl ListArcSafe<0> for Context { untracked; }
> +}
> +kernel::list::impl_list_item! {
> +    impl ListItem<0> for Context {
> +        using ListLinks;
> +    }
> +}

I think at some point it would be worth introducing a derive macro that
does this for us. So for example:

    #[pin_data]
    #[derive(HasListLinks)]
    pub(crate) struct Context {
        #[pin]
        manager: Mutex<Manager>,
        pub(crate) name: CString,
        #[pin]
        #[links]
        links: ListLinks,
    }

And if you need multiple links you could do:

    #[pin_data]
    #[derive(HasListLinks)]
    struct Foo {
        #[links =3D 0]
        a_list: ListLinks,
        #[links =3D 1]
        b_list: ListLinks,
    }

Same for `ListItem` and `HasWork`. I have not yet taken a look at your
linked list implementation, so I don't know if this is possible (since
`ListItem` seems to have multiple "backends").

I think this improvement can wait though, just wanted to mention it.

--=20
Cheers,
Benno