netdev - Re: [PATCH v8 3/7] rust: time: Introduce Instant type

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 for Android: free password hash cracker in your pocket

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

Message-Id: <20250117.083111.1494434582668066369.fujita.tomonori@gmail.com>
Date: Fri, 17 Jan 2025 08:31:11 +0900 (JST)
From: FUJITA Tomonori <fujita.tomonori@...il.com>
To: miguel.ojeda.sandonis@...il.com
Cc: fujita.tomonori@...il.com, linux-kernel@...r.kernel.org,
 boqun.feng@...il.com, rust-for-linux@...r.kernel.org,
 netdev@...r.kernel.org, andrew@...n.ch, hkallweit1@...il.com,
 tmgross@...ch.edu, ojeda@...nel.org, alex.gaynor@...il.com,
 gary@...yguo.net, bjorn3_gh@...tonmail.com, benno.lossin@...ton.me,
 a.hindborg@...sung.com, aliceryhl@...gle.com, anna-maria@...utronix.de,
 frederic@...nel.org, tglx@...utronix.de, arnd@...db.de,
 jstultz@...gle.com, sboyd@...nel.org, mingo@...hat.com,
 peterz@...radead.org, juri.lelli@...hat.com, vincent.guittot@...aro.org,
 dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
 mgorman@...e.de, vschneid@...hat.com
Subject: Re: [PATCH v8 3/7] rust: time: Introduce Instant type

On Thu, 16 Jan 2025 13:37:42 +0100
Miguel Ojeda <miguel.ojeda.sandonis@...il.com> wrote:

> On Thu, Jan 16, 2025 at 5:42 AM FUJITA Tomonori
> <fujita.tomonori@...il.com> wrote:
>>
>> -/// A Rust wrapper around a `ktime_t`.
>> +/// A specific point in time.
>>  #[repr(transparent)]
>>  #[derive(Copy, Clone, PartialEq, PartialOrd, Eq, Ord)]
>> -pub struct Ktime {
>> +pub struct Instant {
>> +    // Range from 0 to `KTIME_MAX`.
> 
> On top of what Tom mentioned: is this intended as an invariant? If
> yes, then please document it publicly in the `Instant` docs in a `#
> Invariants` section. Otherwise, I would clarify this comment somehow,
> since it seems ambiguous.

As I wrote to Tom, that's the kernel's assumption. Do we need to make
it an invariant too?

Or improving the above "Range from 0 to `KTIME_MAX.`" is enough?

The kernel assumes that the range of the ktime_t type is from 0 to
KTIME_MAX. The ktime APIs guarantees to give a valid ktime_t.