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

[FUJITA Tomonori <tomo@flapping.org>]

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.