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

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

Message-Id: <20250122.224635.1710391280729820874.fujita.tomonori@gmail.com>
Date: Wed, 22 Jan 2025 22:46:35 +0900 (JST)
From: FUJITA Tomonori <fujita.tomonori@...il.com>
To: aliceryhl@...gle.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, 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 Wed, 22 Jan 2025 13:51:21 +0100
Alice Ryhl <aliceryhl@...gle.com> wrote:

> On Wed, Jan 22, 2025 at 1:49 PM FUJITA Tomonori
> <fujita.tomonori@...il.com> wrote:
>>
>> On Thu, 16 Jan 2025 21:06:44 +0900 (JST)
>> FUJITA Tomonori <fujita.tomonori@...il.com> wrote:
>>
>> > On Thu, 16 Jan 2025 10:32:45 +0100
>> > Alice Ryhl <aliceryhl@...gle.com> wrote:
>> >
>> >>> -impl Ktime {
>> >>> -    /// Create a `Ktime` from a raw `ktime_t`.
>> >>> +impl Instant {
>> >>> +    /// Create a `Instant` from a raw `ktime_t`.
>> >>>      #[inline]
>> >>> -    pub fn from_raw(inner: bindings::ktime_t) -> Self {
>> >>> +    fn from_raw(inner: bindings::ktime_t) -> Self {
>> >>>          Self { inner }
>> >>>      }
>> >>
>> >> Please keep this function public.
>> >
>> > Surely, your driver uses from_raw()?
>>
>> I checked out the C version of Binder driver and it doesn't seem like
>> the driver needs from_raw function. The Rust version [1] also doesn't
>> seem to need the function. Do you have a different use case?
> 
> Not for this particular function, but I've changed functions called
> from_raw and similar from private to public so many times at this
> point that I think it should be the default.

Then can we remove from_raw()?

We don't use Instant to represent both a specific point in time and a
span of time (we add Delta) so a device driver don't need to create an
Instant from an arbitrary value, I think.

If we allow a device driver to create Instant via from_raw(), we need
to validate a value from the driver. If we create ktime_t only via
ktime_get(), we don't need the details of ktime like a valid range of
ktime_t.