Sinan Kaya [off-list ref] 於 2019年7月15日週一 下午12:17寫道：

On 7/14/2019 11:17 PM, Fuqian Huang wrote:

quoted

In commit 518a2f1925c3
("dma-mapping: zero memory returned from dma_alloc_*"),
dma_alloc_coherent has already zeroed the memory.
So memset is not needed.

Signed-off-by: Fuqian Huang <redacted>

I don't see SWIO or ARM64 IOMMU drivers getting impacted by
the mentioned change above (518a2f1925c3).

How does this new behavior apply globally?

In the last version patch set, I referenced the commit af7ddd8a627c
("Merge tag 'dma-mapping-4.21' of
git://git.infradead.org/users/hch/dma-mapping")
in the commit log.
The merged commit mentions that
"ensure dma_alloc_coherent returns zeroed memory to
avoid kernel data leaks through userspace.
We already did this for most common architectures,
but this ensures we do it everywhere."
dma_alloc_coherent has already zeroed the memory during allocation
and the commit also deprecates dma_zalloc_coherent.
Greg and other maintainer told me to use the actual commit
rather than the merged commit.
So I reference the commit that ensures the dma_alloc_coherent to
returns zeroed memory every where.
Maybe this belongs to the `most common achitectures` and is not impacted
by the mentioned change.
Should I rewrite the commit log? Just mention that dma_alloc_coherent
has already
zeroed the memory and not to reference the commit?

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