vhost_net: correctly limit the max pending buffers

[cascardo/linux.git] / drivers / vhost / net.c

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 8e9dc55..831eb4f 100644 (file)
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -363,6 +363,13 @@ static void handle_tx(struct vhost_net *net)
                if (zcopy)
                        vhost_zerocopy_signal_used(net, vq);
 
+               /* If more outstanding DMAs, queue the work.
+                * Handle upend_idx wrap around
+                */
+               if (unlikely((nvq->upend_idx + vq->num - VHOST_MAX_PEND)
+                             % UIO_MAXIOV == nvq->done_idx))
+                       break;
+
                head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
                                         ARRAY_SIZE(vq->iov),
                                         &out, &in,
@@ -372,17 +379,6 @@ static void handle_tx(struct vhost_net *net)
                        break;
                /* Nothing new?  Wait for eventfd to tell us they refilled. */
                if (head == vq->num) {
-                       int num_pends;
-
-                       /* If more outstanding DMAs, queue the work.
-                        * Handle upend_idx wrap around
-                        */
-                       num_pends = likely(nvq->upend_idx >= nvq->done_idx) ?
-                                   (nvq->upend_idx - nvq->done_idx) :
-                                   (nvq->upend_idx + UIO_MAXIOV -
-                                    nvq->done_idx);
-                       if (unlikely(num_pends > VHOST_MAX_PEND))
-                               break;
                        if (unlikely(vhost_enable_notify(&net->dev, vq))) {
                                vhost_disable_notify(&net->dev, vq);
                                continue;