vhost, vhost_net: add helper to check if vq has work

In the next patches each vq might have different workers so one could
have work but others do not. For net, we only want to check specific vqs,
so this adds a helper to check if a vq has work pending and converts
vhost-net to use it.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20230626232307.97930-5-michael.christie@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vhost/net.c

@@ -546,7 +546,7 @@ static void vhost_net_busy_poll(struct vhost_net *net,
 	endtime = busy_clock() + busyloop_timeout;
 
 	while (vhost_can_busy_poll(endtime)) {
-		if (vhost_has_work(&net->dev)) {
+		if (vhost_vq_has_work(vq)) {
 			*busyloop_intr = true;
 			break;
 		}

drivers/vhost/vhost.c

@@ -266,11 +266,11 @@ bool vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
 EXPORT_SYMBOL_GPL(vhost_work_queue);
 
 /* A lockless hint for busy polling code to exit the loop */
-bool vhost_has_work(struct vhost_dev *dev)
+bool vhost_vq_has_work(struct vhost_virtqueue *vq)
 {
-	return !llist_empty(&dev->worker->work_list);
+	return !llist_empty(&vq->worker->work_list);
 }
-EXPORT_SYMBOL_GPL(vhost_has_work);
+EXPORT_SYMBOL_GPL(vhost_vq_has_work);
 
 void vhost_poll_queue(struct vhost_poll *poll)
 {

drivers/vhost/vhost.h

@@ -45,7 +45,6 @@ struct vhost_poll {
 
 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
 bool vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work);
-bool vhost_has_work(struct vhost_dev *dev);
 
 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
 		     __poll_t mask, struct vhost_dev *dev);
@@ -199,6 +198,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *,
 		      struct vhost_log *log, unsigned int *log_num);
 void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
 
+bool vhost_vq_has_work(struct vhost_virtqueue *vq);
 bool vhost_vq_is_setup(struct vhost_virtqueue *vq);
 int vhost_vq_init_access(struct vhost_virtqueue *);
 int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);