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AJvYcCWj7WnMxO1UkOeObuRZpvcjyxPYIUbY3r4Fd97NZ488zh9S3k2bx3bgHU7eeR055Eqgt6gNkPDIKU/c4bocZPsj4YQ= X-Gm-Message-State: AOJu0Yxu9S0x2U2fg9LuunOvcOIEAwKNN4YjCFz8fN8RKx6KX+QWig/V 7UB3FJs5TydArHfmtsGSQwctOJHa5Fq1J6+ykX0eo3Qkb8CnIYOypjOx01HcD3fW1MW467DLlFQ u0JnQqW4YkMd0Wh6TkC3VoVteW7g+LVkD0Ep1 X-Google-Smtp-Source: AGHT+IE3ctn60mbisPE+3PgDQzWKYFH4fz7jLn6kIz89GDQBsxDl4h15/TtK0Z8YFRnQV/FF1toMip/RgGPmLJg1kxc= X-Received: by 2002:a05:6122:4809:b0:4d3:35ac:3553 with SMTP id ef9-20020a056122480900b004d335ac3553mr4054281vkb.10.1712568394315; Mon, 08 Apr 2024 02:26:34 -0700 (PDT) MIME-Version: 1.0 References: <20240404-alice-mm-v4-0-49a84242cf02@google.com> <20240404-alice-mm-v4-4-49a84242cf02@google.com> In-Reply-To: From: Alice Ryhl Date: Mon, 8 Apr 2024 11:26:23 +0200 Message-ID: Subject: Re: [PATCH v4 4/4] rust: add abstraction for `struct page` To: Miguel Ojeda Cc: Benno Lossin , Miguel Ojeda , Matthew Wilcox , Al Viro , Andrew Morton , Kees Cook , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= , Andreas Hindborg , Greg Kroah-Hartman , =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= , Todd Kjos , Martijn Coenen , Joel Fernandes , Carlos Llamas , Suren Baghdasaryan , Arnd Bergmann , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, Christian Brauner Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 6495C40011 X-Rspam-User: X-Stat-Signature: objinzeorqfh97rd75p8effs4rqg8849 X-Rspamd-Server: rspam01 X-HE-Tag: 1712568395-312814 X-HE-Meta: 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 XnHbTePa UxAoAFsd416/dFVIWOEwO6dmBZ2QJ018oakvfscBbhpiKdrzWaY+FyYU2aXWj4dwAMna5OPxSAA6H4P7a10LucFX0o+IoLxSO2uMs3nA9AASe7d+bDJDAb0WLkUryNJAMm8ObkcIw4S3Cqo0CY3j/Ro4df5/3IzA9BQA90Z1peNezM1nfcICfsMkCQPERlv01pKCSp9rvTb/AEyVUD0oL/jLapnhCQaagLhZmB1VLC/qWS73+CuT/1N1DG0HYnj/35LHh4RDuJXcUKT8FfTKjFKMyA+TqgM4/7R+9X44yiq4vO22FVYJfXwGWtzcf/b5ATajvtRIuhlqnS3b4xorobz/VQkEdvlvAN5kW X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Apr 8, 2024 at 11:19=E2=80=AFAM Miguel Ojeda wrote: > > On Mon, Apr 8, 2024 at 9:54=E2=80=AFAM Alice Ryhl = wrote: > > > > From bindgen's point of view, this constant is just an integer literal > > with no type information. So I don't see how we can expect it to > > always be generated as a usize? > > In the case of `PAGE_SIZE`, there is type information (`size_t`), > since it comes from the constant helper: > > const size_t RUST_CONST_HELPER_PAGE_SIZE =3D PAGE_SIZE; > > For the other one, `PAGE_SHIFT`, there is also type information > (`int`), but bindgen currently picks a type based on the value for > those (but ideally/eventually bindgen should respect it instead). > > So for the former, the allow and the cast are not needed since we are > already handling it explicitly. And for the latter, if we want to have > it as `usize`, we should have the cast but not the allow, because now > it does `u32`, but if it respected the type, it would be `c_int` or > `i32`. So either way we would need the cast. Good point. Will fix this for next version. Alice