linux-kernel - Re: [PATCH v2 4/4] rust: sync: update integer types in CondVar

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <76415f1d-174c-4cee-9b58-e956be6bda54@gmail.com>
Date: Sat, 16 Dec 2023 13:42:30 -0300
From: Martin Rodriguez Reboredo <yakoyoku@...il.com>
To: Alice Ryhl <aliceryhl@...gle.com>, Miguel Ojeda <ojeda@...nel.org>,
 Alex Gaynor <alex.gaynor@...il.com>,
 Wedson Almeida Filho <wedsonaf@...il.com>, Boqun Feng
 <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>,
 Björn Roy Baron <bjorn3_gh@...tonmail.com>,
 Benno Lossin <benno.lossin@...ton.me>,
 Andreas Hindborg <a.hindborg@...sung.com>,
 Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
 Will Deacon <will@...nel.org>, Waiman Long <longman@...hat.com>,
 Tiago Lam <tiagolam@...il.com>, Thomas Gleixner <tglx@...utronix.de>
Cc: rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/4] rust: sync: update integer types in CondVar

On 12/16/23 12:31, Alice Ryhl wrote:
> Reduce the chances of compilation failures due to integer type
> mismatches in `CondVar`.
> 
> When an integer is defined using a #define in C, bindgen doesn't know
> which integer type it is supposed to be, so it will just use `u32` by
> default (if it fits in an u32). Whenever the right type is something
> else, we insert a cast in Rust. However, this means that the code has a
> lot of extra casts, and sometimes the code will be missing casts if u32
> happens to be correct on the developer's machine, even though the type
> might be something else on a different platform.
> 
> This patch updates all uses of such constants in
> `rust/kernel/sync/condvar.rs` to use constants defined with the right
> type. This allows us to remove various unnecessary casts, while also
> future-proofing for the case where `unsigned int != u32`.
> 
> I wrote this patch at the suggestion of Benno in [1].
> 
> Link: https://lore.kernel.org/all/nAEg-6vbtX72ZY3oirDhrSEf06TBWmMiTt73EklMzEAzN4FD4mF3TPEyAOxBZgZtjzoiaBYtYr3s8sa9wp1uYH9vEWRf2M-Lf4I0BY9rAgk=@proton.me/ [1]
> Suggested-by: Benno Lossin <benno.lossin@...ton.me>
> Signed-off-by: Alice Ryhl <aliceryhl@...gle.com>
> ---
> [...]
> @@ -174,22 +178,15 @@ pub fn wait_interruptible_timeout<T: ?Sized, B: Backend>(
>       }
>   
>       /// Calls the kernel function to notify the appropriate number of threads with the given flags.

There are no more flags, please update the comment.

> -    fn notify(&self, count: i32, flags: u32) {
> +    fn notify(&self, count: c_int) {
>           // SAFETY: `wait_list` points to valid memory.
> -        unsafe {
> -            bindings::__wake_up(
> -                self.wait_list.get(),
> -                bindings::TASK_NORMAL,
> -                count,
> -                flags as _,
> -            )
> -        };
> +        unsafe { bindings::__wake_up(self.wait_list.get(), TASK_NORMAL, count, ptr::null_mut()) };
>       }
> [...]