Hi Ling,
On 5/14/21 6:02 PM, Balazs Nemeth wrote: > The optimization introduced by commit d18db8049c7c ("vhost: read last > used index once") didn't account for the fact that > vhost_flush_enqueue_shadow_packed increments the last_used_idx. For this > reason, store last_used_idx after the potential call to > vhost_flush_enqueue_shadow_packed. > > Fixes: d18db8049c7c ("vhost: read last used index once") > Signed-off-by: Balazs Nemeth <bnem...@redhat.com> > --- > lib/vhost/virtio_net.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c > index abfd67d38c..8da8a86a10 100644 > --- a/lib/vhost/virtio_net.c > +++ b/lib/vhost/virtio_net.c > @@ -218,14 +218,17 @@ vhost_flush_enqueue_batch_packed(struct virtio_net *dev, > { > uint16_t i; > uint16_t flags; > - uint16_t last_used_idx = vq->last_used_idx; > - struct vring_packed_desc *desc_base = &vq->desc_packed[last_used_idx]; > + uint16_t last_used_idx; > + struct vring_packed_desc *desc_base; > > if (vq->shadow_used_idx) { > do_data_copy_enqueue(dev, vq); > vhost_flush_enqueue_shadow_packed(dev, vq); > } > > + last_used_idx = vq->last_used_idx; > + desc_base = &vq->desc_packed[last_used_idx]; > + > flags = PACKED_DESC_ENQUEUE_USED_FLAG(vq->used_wrap_counter); > > vhost_for_each_try_unroll(i, 0, PACKED_BATCH_SIZE) { > Could you please confirm the patch fixes the issue you reported? Thanks, Maxime