Re: [PATCH v8 4/4] rust: sync: condvar: use Delta<Jiffy> for timeout and result

["Gary Guo" <gary@garyguo.net>]

On Fri Oct 2, 2026 at 12:05 PM BST, FUJITA Tomonori wrote:
> On Fri, 02 Oct 2026 11:00:40 +0100
> "Gary Guo" <gary@garyguo.net> wrote:
>
>> On Fri Oct 2, 2026 at 6:04 AM BST, FUJITA Tomonori wrote:
>>> From: FUJITA Tomonori <fujita.tomonori@gmail.com>
>
> [...]
>
>>> @@ -182,19 +185,29 @@ pub fn wait_interruptible_freezable<T: ?Sized, B: Backend>(
>>>      /// Atomically releases the given lock (whose ownership is proven by the guard) and puts the
>>>      /// thread to sleep. It wakes up when notified by [`CondVar::notify_one`] or
>>>      /// [`CondVar::notify_all`], or when a timeout occurs, or when the thread receives a signal.
>>> +    ///
>>> +    /// A negative timeout is treated as zero.
>>>      #[must_use = "wait_interruptible_timeout returns if a signal is pending, so the caller must check the return value"]
>>>      pub fn wait_interruptible_timeout<T: ?Sized, B: Backend>(
>>>          &self,
>>>          guard: &mut Guard<'_, T, B>,
>>> -        jiffies: Jiffies,
>>> +        delta: Delta<Jiffy>,
>>>      ) -> CondVarTimeoutResult {
>>> -        let jiffies = jiffies.try_into().unwrap_or(MAX_SCHEDULE_TIMEOUT);
>>> -        let res = self.wait_internal(TASK_INTERRUPTIBLE, guard, jiffies);
>>> +        let jiffies = delta.as_jiffies();
>>> +        let res = self.wait_internal(
>>> +            TASK_INTERRUPTIBLE,
>>> +            guard,
>>> +            jiffies.clamp(0, MAX_SCHEDULE_TIMEOUT),
>> 
>> I suppose this can be `delta.as_jiffies_unsigned()` too, although the clamp
>> makes it more explicit?
>
> wait_internal() takes isize, so with as_jiffies_unsigned() we
> need to cast the value back:
>
> | // CAST: `as_jiffies_unsigned()` returns at most `isize::MAX`, so the
> | // value fits in `isize`.
> | let jiffies = delta.as_jiffies_unsigned() as isize;
> | let res = self.wait_internal(TASK_INTERRUPTIBLE, guard, jiffies);
>
> The clamp needs no cast, so I'd keep it.

Right, sounds reasonable. This can also be `isize::max(delta.as_jiffies(), 0)` I
suppose, but `clamp` reads fine too.

Best,
Gary