tap: support enabling or disabling a queue

This patch introduce a new bit - enabled in TAPState which tracks whether a
specific queue/fd is enabled. The tap/fd is enabled during initialization and
could be enabled/disabled by tap_enalbe() and tap_disable() which calls platform
specific helpers to do the real work. Polling of a tap fd can only done when
the tap was enabled.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/net/tap-win32.c b/net/tap-win32.c
index 601437ee2d..91e9e844a0 100644
--- a/net/tap-win32.c
+++ b/net/tap-win32.c
@@ -764,3 +764,13 @@ void tap_set_vnet_hdr_len(NetClientState *nc, int len)
 {
     abort();
 }
+
+int tap_enable(NetClientState *nc)
+{
+    abort();
+}
+
+int tap_disable(NetClientState *nc)
+{
+    abort();
+}