If the packet uses multiple descriptors and its descriptor indices are
wrapped, the first descriptor flag is not updated last, which may cause
virtio read the incomplete packet. For example, given a packet uses 64
descriptors, and virtio ring size is 256, and its descriptor indices are
224~255 and 0~31, current implementation will update 224~255 descriptor
flags earlier than 0~31 descriptor flags.
This patch fixes this issue by updating descriptor flags in one loop,
so that the first descriptor flag is always updated last.
Fixes: 873e8dad6f49 ("vhost: support packed ring in async datapath")
Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
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