Re: [PATCH] virtio_ring: skip cpu sync when mapping fails

Jason Wang
2025-01-10T03:33:01Z

On Wed, Jan 8, 2025 at 7:35 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Mon, Nov 11, 2024 at 10:55:38AM +0800, Jason Wang wrote:
> > There's no need to sync DMA for CPU on mapping errors. So this patch
> > skips the CPU sync in the error handling path of DMA mapping.
> >
> > Signed-off-by: Jason Wang <jasowang@redhat.com>
>
>
> So as I said, I do not get why we are optimizing error paths.
> The commit log at least needs to be improved to document
> the motivation.

As replied before. Does the following make more sense?

1) dma_map_sg() did this
2) When the driver tries to submit more buffers than SWIOTLB allows,
dma_map might fail, in these cases, bouncing is useless.

Thanks