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Date: Tue, 19 Mar 2024 22:28:52 +0000
To: Boqun Feng <boqun.feng@gmail.com>, Alice Ryhl <aliceryhl@google.com>
From: Benno Lossin <benno.lossin@proton.me>
Cc: Miguel Ojeda <ojeda@kernel.org>, Matthew Wilcox <willy@infradead.org>, Al Viro <viro@zeniv.linux.org.uk>, Andrew Morton <akpm@linux-foundation.org>, Kees Cook <keescook@chromium.org>, Alex Gaynor <alex.gaynor@gmail.com>, Wedson Almeida Filho <wedsonaf@gmail.com>, Gary Guo <gary@garyguo.net>, =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>, Andreas Hindborg <a.hindborg@samsung.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, =?utf-8?Q?Arve_Hj=C3=B8nnev=C3=A5g?= <arve@android.com>, Todd Kjos <tkjos@android.com>, Martijn Coenen <maco@android.com>, Joel Fernandes <joel@joelfernandes.org>, Carlos Llamas <cmllamas@google.com>, Suren Baghdasaryan <surenb@google.com>, Arnd Bergmann <arnd@arndb.de>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, Christian Brauner <brauner@kernel.org>
Subject: Re: [PATCH v3 4/4] rust: add abstraction for `struct page`
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In-Reply-To: <ZfoO1h0Kzdz4ln26@boqun-archlinux>
References: <20240311-alice-mm-v3-0-cdf7b3a2049c@google.com> <20240311-alice-mm-v3-4-cdf7b3a2049c@google.com> <ZfoO1h0Kzdz4ln26@boqun-archlinux>
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On 3/19/24 23:16, Boqun Feng wrote:
> On Mon, Mar 11, 2024 at 10:47:16AM +0000, Alice Ryhl wrote:
> [...]
>>   /* `bindgen` gets confused at certain things. */
>>   const size_t RUST_CONST_HELPER_ARCH_SLAB_MINALIGN =3D ARCH_SLAB_MINALI=
GN;
>> +const size_t RUST_CONST_HELPER_PAGE_SIZE =3D PAGE_SIZE;
>> +const size_t RUST_CONST_HELPER_PAGE_MASK =3D PAGE_MASK;
>=20
> At least for me, bindgen couldn't work out the macro expansion, and I
> got:
>=20
> =09pub const PAGE_SIZE: usize =3D 4096;
> =09extern "C" {
> =09    pub static RUST_CONST_HELPER_PAGE_MASK: usize;
> =09}
>=20
> in rust/bindings/bindings_generated.rs, which will eventually cause the
> code cannot compile.
>=20
> I'm using bindgen-cli 0.65.1, libclang (16 or 17), rustc (1.76 or 1.77).
>=20
> Anyone else sees the same thing?

I also have this problem with bindgen-cli 0.69.1 libclang 16 and rustc 1.76=
0.
For reference, here is the actual compilation error:

error[E0425]: cannot find value `PAGE_MASK` in crate `bindings`
      --> rust/kernel/page.rs:17:40
       |
17    | pub const PAGE_MASK: usize =3D bindings::PAGE_MASK as usize;
       |                                        ^^^^^^^^^ help: a constant =
with a similar name exists: `GATE_TASK`
       |
      ::: /home/benno/kernel/review/mem-man-binder/rust/bindings/bindings_g=
enerated.rs:12188:1
       |
12188 | pub const GATE_TASK: _bindgen_ty_4 =3D 5;
       | ---------------------------------- similarly named constant `GATE_=
TASK` defined here

error: type `gfp_t` should have an upper camel case name
   --> rust/kernel/page.rs:21:14
    |
21 |     pub type gfp_t =3D bindings::gfp_t;
    |              ^^^^^ help: convert the identifier to upper camel case: =
`GfpT`
    |
    =3D note: `-D non-camel-case-types` implied by `-D warnings`
    =3D help: to override `-D warnings` add `#[allow(non_camel_case_types)]=
`

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0425`.

@Alice: the second error should be unrelated to this problem.

--=20
Cheers,
Benno

>=20
> Regards,
> Boqun
>=20
>>   const gfp_t RUST_CONST_HELPER_GFP_KERNEL =3D GFP_KERNEL;
>>   const gfp_t RUST_CONST_HELPER___GFP_ZERO =3D __GFP_ZERO;
>> +const gfp_t RUST_CONST_HELPER___GFP_HIGHMEM =3D ___GFP_HIGHMEM;
> [...]