Re: [PATCH v9] rust: sync: condvar: use Delta<Jiffy> for timeout and result

[FUJITA Tomonori <tomo@flapping.org>]

On Mon, 2 Nov 2026 07:51:29 -0800
Boqun Feng <boqun@kernel.org> wrote:

> On Mon, Nov 02, 2026 at 12:59:34PM +0900, FUJITA Tomonori wrote:
>> From: FUJITA Tomonori <fujita.tomonori@gmail.com>
>> 
>> wait_interruptible_timeout() takes the timeout as a raw Jiffies, and
>> CondVarTimeoutResult reports the remaining time as a raw Jiffies. The
>> type does not show the unit.
>> 
>> Switch the parameter and the result fields to Delta<Jiffy>.
>> 
>> Delta<Jiffy> is signed, but schedule_timeout() prints an error and a
>> stack dump for a negative timeout. Clamp a negative timeout to zero, so
>> it means an immediate timeout.
>> 
>> Update the only user, binder. It now converts the freeze timeout with
>> Delta::to_jiffies_timeout() instead of msecs_to_jiffies(). Both round
>> up, so a short timeout does not become zero. They differ only for a
>> very long timeout. msecs_to_jiffies() returns MAX_JIFFY_OFFSET for
>> 2^31 ms (about 24.9 days) or more, which means an infinite
>> timeout. to_jiffies_timeout() has no such special case. It converts
>> such a value to the matching number of jiffies, so the wait is long
>> but finite.
>> 
>> Reviewed-by: Gary Guo <gary@garyguo.net>
>> Signed-off-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
> 
> Thanks. Alice, any concern regarding the change in binder?
> 
> I have some naming suggestion, please see below:

[...]

>> @@ -248,11 +261,11 @@ pub enum CondVarTimeoutResult {
>>      /// Somebody woke us up.
>>      Woken {
>>          /// Remaining sleep duration.
>> -        jiffies: Jiffies,
>> +        jiffies: Delta<Jiffy>,
>>      },
>>      /// A signal occurred.
>>      Signal {
>>          /// Remaining sleep duration.
>> -        jiffies: Jiffies,
>> +        jiffies: Delta<Jiffy>,
> 
> Similar for these two: s/jiffies/remainder
> 
> Thoughts?

Sounds good to me. Now that the type shows the unit, the names should
say what the value means. I'll rename all of them in v10.

I'll wait a few days for Alice's comment on the binder change before
sending v10.