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The copy is best-effort there - it cannot be made > atomic either way - but reading a non-zero 'put' and then reading > contents that predate it is indeed the pattern dma_rmb() exists for. > > I am happy to add it, but there is no dma_rmb() abstraction in > rust/kernel at the moment: sync/barrier.rs only provides the smp_* > family, and smp_rmb() is not a correct substitute, as on arm64 it uses > the inner shareable domain rather than the outer shareable one that > dma_rmb() needs. See https://lore.kernel.org/rust-for-linux/20260609-rust-barrier-v2-0-30fcc48e1= cd0@garyguo.net/ The abstraction part is being upstreamed via tip tree, so they're not curre= ntly present in drm-rust.next. It'll be there when the next backmerge happens. > > Would you prefer a small prerequisite patch adding dma_rmb() to > rust/kernel, or is relying on the unload ordering acceptable, with the > requirement spelled out in a comment on snapshot()? Sashiko is a patch review bot so you won't get any response by asking it -- although I suppose this message is written by a LLM too. Best, Gary