Re: [PATCH v9 05/14] ALSA: virtio: Keep control payloads alive through DMA completion

[sashiko-bot@kernel.org]

> Control requests can expose caller-owned payloads to the device after a
> synchronous send times out. Keep request and response headers and payloads
> in the reference-counted message so caller cleanup cannot invalidate DMA.
> 
> Keep the queue reference until device completion or post-reset cleanup,
> even when the caller times out or is interrupted. Consume the caller's
> reference on every send path, and let response readers retain an extra
> reference through copyout. Check payload sizes and allocation arithmetic
> before building the scatterlists.
> 
> A control value payload is also read by the CPU as a typed structure. DMA
> cacheline alignment alone does not guarantee the structure's CPU alignment.
> Align regions to the greater of the DMA cacheline and control-value type
> alignment, and reserve prefix slack from the buffer base so typed accesses
> remain aligned while scatterlist regions stay on cacheline boundaries.
> 
> Keep response values in a separately allocated aligned response buffer
> so INTEGER64 control accesses are aligned from this patch onward.
> 
> Fixes: 9d45e514da88 ("ALSA: virtio: handling control messages")
> Assisted-by: LLM
> Signed-off-by: Joonho Lee <mynameisjune111@gmail.com>

Sashiko has reviewed this patch and found no issues.

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