Re: [PATCH 2/6] rust: hrtimer: Add HrTimerCallbackContext and ::forward()

From: Lyude Paul
Date: Wed Apr 09 2025 - 13:15:30 EST


On Wed, 2025-04-09 at 12:58 -0400, Lyude Paul wrote:
>
> Pin<&'a T> is noticeably absent, because I'm not sure it could fulfill these
> requirements. That being said - assuming we fulfill the unique ownership
> requirement, I believe that for all the unique aforementioned types it
> wouldn't be possible to take out a timer handle when they're in scope anyhow.
> So we probably could skip the cancel() call?

Nope - realizing this doesn't solve the edge case of "what if someone tried
calling a contextless forward() from within the context of the timer callback
itself" since uniqueness doesn't actually mean the timer is cancelled. So I
think your suggestion of returning Err() if the timer is already running might
actually be the way to go here. I think we would still need to ensure
uniqueness though, since that can at least guarantee that the timer won't be
requeued between us checking it and before we manage to call
hrtimer_forward().

>
>
> >
> >
> > Best regards,
> > Andreas Hindborg
> >
> >
>

--
Cheers,
Lyude Paul (she/her)
Software Engineer at Red Hat

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