+
+/* Calls ioctl() on an AF_LINK sock, passing the specified 'command' and
+ * 'arg'. Returns 0 if successful, otherwise a positive errno value. */
+int
+af_link_ioctl(int command, const void *arg)
+{
+ static struct ovsthread_once once = OVSTHREAD_ONCE_INITIALIZER;
+ static int sock;
+
+ if (ovsthread_once_start(&once)) {
+ sock = socket(AF_LINK, SOCK_DGRAM, 0);
+ if (sock < 0) {
+ sock = -errno;
+ VLOG_ERR("failed to create link socket: %s", ovs_strerror(errno));
+ }
+ ovsthread_once_done(&once);
+ }
+
+ return (sock < 0 ? -sock
+ : ioctl(sock, command, arg) == -1 ? errno
+ : 0);
+}