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[2/3] virtio: introduce virtqueue_discard()

Message ID 1442563270-11615-2-git-send-email-jasowang@redhat.com
State New
Headers show

Commit Message

Jason Wang Sept. 18, 2015, 8:01 a.m. UTC 
This patch introduces virtqueue_discard() to discard a descriptor and
unmap the sgs. This will be used by the patch that will discard
descriptor when packet is truncated.

Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 hw/virtio/virtio.c         | 7 +++++++
 include/hw/virtio/virtio.h | 2 ++
 2 files changed, 9 insertions(+)
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Patch

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index eb8d5ca..d24ee80 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -265,6 +265,13 @@  static void virtqueue_unmap_sg(VirtQueue *vq, const VirtQueueElement *elem,
                                   0, elem->out_sg[i].iov_len);
 }
 
+void virtqueue_discard(VirtQueue *vq, const VirtQueueElement *elem,
+                       unsigned int len)
+{
+    vq->last_avail_idx--;
+    virtqueue_unmap_sg(vq, elem, len);
+}
+
 void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
                     unsigned int len, unsigned int idx)
 {
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 6201ee8..9d09115 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -146,6 +146,8 @@  void virtio_del_queue(VirtIODevice *vdev, int n);
 void virtqueue_push(VirtQueue *vq, const VirtQueueElement *elem,
                     unsigned int len);
 void virtqueue_flush(VirtQueue *vq, unsigned int count);
+void virtqueue_discard(VirtQueue *vq, const VirtQueueElement *elem,
+                       unsigned int len);
 void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
                     unsigned int len, unsigned int idx);