Re: [RFC PATCH 2/4] rust: sync: Add dma_fence abstractions

[Boris Brezillon <boris.brezillon@collabora.com>]

On Tue, 10 Feb 2026 10:15:04 +0000
Alice Ryhl <aliceryhl@google.com> wrote:

> /// The owner of this value must ensure that this fence is signalled.
> struct MustBeSignalled<'fence> { ... }
> /// Proof value indicating that the fence has either already been
> /// signalled, or it will be. The lifetime ensures that you cannot mix
> /// up the proof value.
> struct WillBeSignalled<'fence> { ... }

Sorry, I have more questions, unfortunately. Seems that
{Must,Will}BeSignalled are targeting specific fences (at least that's
what the doc and 'fence lifetime says), but in practice, the WorkItem
backing the scheduler can queue 0-N jobs (0 if no jobs have their deps
met, and N > 1 if more than one job is ready). Similarly, an IRQ
handler can signal 0-N fences (can be that the IRQ has nothing to do we
job completion, or, it can be that multiple jobs have completed). How
is this MustBeSignalled object going to be instantiated in practice if
it's done before the DmaFenceWorkItem::run() function is called?