vhost: refine new device function

Make sure find avalid device id before allocating
virtio_net, if not, return directly. It may avoid
allocating and freeing virtio_net when there is
not valid device id.

Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
index afded49..ed7b7ac 100644 (file)
--- a/lib/librte_vhost/vhost.c
+++ b/lib/librte_vhost/vhost.c
@@ -268,21 +268,21 @@ vhost_new_device(void)
        struct virtio_net *dev;
        int i;
 
-       dev = rte_zmalloc(NULL, sizeof(struct virtio_net), 0);
-       if (dev == NULL) {
-               RTE_LOG(ERR, VHOST_CONFIG,
-                       "Failed to allocate memory for new dev.\n");
-               return -1;
-       }
-
        for (i = 0; i < MAX_VHOST_DEVICE; i++) {
                if (vhost_devices[i] == NULL)
                        break;
        }
+
        if (i == MAX_VHOST_DEVICE) {
                RTE_LOG(ERR, VHOST_CONFIG,
                        "Failed to find a free slot for new device.\n");
-               rte_free(dev);
+               return -1;
+       }
+
+       dev = rte_zmalloc(NULL, sizeof(struct virtio_net), 0);
+       if (dev == NULL) {
+               RTE_LOG(ERR, VHOST_CONFIG,
+                       "Failed to allocate memory for new dev.\n");
                return -1;
        }