[RFC,12/27] virtio: Add virtio_queue_full

Commit Message

Eugenio Perez Martin Nov. 20, 2020, 6:50 p.m. UTC

Signed-off-by: Eugenio Pérez <[e-mail]>
---
 include/hw/virtio/virtio.h |  2 ++
 hw/virtio/virtio.c         | 15 +++++++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

Patch

diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index b9b8497ea0..0a7f5cc63e 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -233,6 +233,8 @@  int virtio_queue_ready(VirtQueue *vq);
 
 int virtio_queue_empty(VirtQueue *vq);
 
+bool virtio_queue_full(const VirtQueue *vq);
+
 /* Host binding interface.  */
 
 uint32_t virtio_config_readb(VirtIODevice *vdev, uint32_t addr);
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 3469946538..77ca5f6b6f 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -684,6 +684,17 @@  int virtio_queue_empty(VirtQueue *vq)
     }
 }
 
+static bool virtio_queue_full_rcu(const VirtQueue *vq)
+{
+    return vq->inuse >= vq->vring.num;
+}
+
+bool virtio_queue_full(const VirtQueue *vq)
+{
+    RCU_READ_LOCK_GUARD();
+    return virtio_queue_full_rcu(vq);
+}
+
 static void virtqueue_unmap_sg(VirtQueue *vq, const VirtQueueElement *elem,
                                unsigned int len)
 {
@@ -1453,7 +1464,7 @@  static void *virtqueue_split_pop(VirtQueue *vq, size_t sz)
 
     max = vq->vring.num;
 
-    if (vq->inuse >= vq->vring.num) {
+    if (unlikely(virtio_queue_full_rcu(vq))) {
         virtio_error(vdev, "Virtqueue size exceeded");
         goto done;
     }
@@ -1588,7 +1599,7 @@  static void *virtqueue_packed_pop(VirtQueue *vq, size_t sz)
 
     max = vq->vring.num;
 
-    if (vq->inuse >= vq->vring.num) {
+    if (unlikely(virtio_queue_full_rcu(vq))) {
         virtio_error(vdev, "Virtqueue size exceeded");
         goto done;
     }