On Wed, Sep 27, 2023 at 1:53 PM Xuan Zhuo <xuanz...@linux.alibaba.com> wrote:
>
> Commit 295525e29a5b ("virtio_net: merge dma operations when filling
> mergeable buffers") unmaps the buffer with DMA_ATTR_SKIP_CPU_SYNC when
> the dma->ref is zero. We do that with DMA_ATTR_SKIP_CPU_SYNC, because we
> do not want to do the sync for the entire page_frag. But that misses the
> sync for the current area.
>
> This patch does cpu sync regardless of whether the ref is zero or not.
>
> Fixes: 295525e29a5b ("virtio_net: merge dma operations when filling mergeable
> buffers")
> Reported-by: Michael Roth <michael.r...@amd.com>
> Closes: http://lore.kernel.org/all/20230926130451.axgodaa6tvwqs...@amd.com
> Signed-off-by: Xuan Zhuo <xuanz...@linux.alibaba.com>
Acked-by: Jason Wang <jasow...@redhat.com>
Thanks
> ---
> drivers/net/virtio_net.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 98dc9b49d56b..9ece27dc5144 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -589,16 +589,16 @@ static void virtnet_rq_unmap(struct receive_queue *rq,
> void *buf, u32 len)
>
> --dma->ref;
>
> - if (dma->ref) {
> - if (dma->need_sync && len) {
> - offset = buf - (head + sizeof(*dma));
> + if (dma->need_sync && len) {
> + offset = buf - (head + sizeof(*dma));
>
> - virtqueue_dma_sync_single_range_for_cpu(rq->vq,
> dma->addr, offset,
> - len,
> DMA_FROM_DEVICE);
> - }
> + virtqueue_dma_sync_single_range_for_cpu(rq->vq, dma->addr,
> + offset, len,
> + DMA_FROM_DEVICE);
> + }
>
> + if (dma->ref)
> return;
> - }
>
> virtqueue_dma_unmap_single_attrs(rq->vq, dma->addr, dma->len,
> DMA_FROM_DEVICE,
> DMA_ATTR_SKIP_CPU_SYNC);
> --
> 2.32.0.3.g01195cf9f
>
>
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