commit 16dbaf905b72636d1bb066968bceabd64eaa1a9d
author Jason Wang <jasowang@redhat.com> Wed Jan 30 19:12:32 2013 +0800
committer Anthony Liguori <aliguori@us.ibm.com> Fri Feb 01 11:03:02 2013 -0600
tree be250670ab1dc6f35a705ca2ebbcd59c973eb486
parent 94fdc6d03034f594c53d5413590e23fcb7ffc268

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>

net/tap.c

diff --git a/net/tap.c b/net/tap.c
index 23fb6e0..8610ba2 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -59,6 +59,7 @@
     bool write_poll;
     bool using_vnet_hdr;
     bool has_ufo;
+    bool enabled;
     VHostNetState *vhost_net;
     unsigned host_vnet_hdr_len;
 } TAPState;
@@ -72,9 +73,9 @@
 static void tap_update_fd_handler(TAPState *s)
 {
     qemu_set_fd_handler2(s->fd,
-                         s->read_poll  ? tap_can_send : NULL,
-                         s->read_poll  ? tap_send     : NULL,
-                         s->write_poll ? tap_writable : NULL,
+                         s->read_poll && s->enabled ? tap_can_send : NULL,
+                         s->read_poll && s->enabled ? tap_send     : NULL,
+                         s->write_poll && s->enabled ? tap_writable : NULL,
                          s);
 }
 
@@ -337,6 +338,7 @@
     s->host_vnet_hdr_len = vnet_hdr ? sizeof(struct virtio_net_hdr) : 0;
     s->using_vnet_hdr = false;
     s->has_ufo = tap_probe_has_ufo(s->fd);
+    s->enabled = true;
     tap_set_offload(&s->nc, 0, 0, 0, 0, 0);
     /*
      * Make sure host header length is set correctly in tap:
@@ -735,3 +737,38 @@
     assert(nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP);
     return s->vhost_net;
 }
+
+int tap_enable(NetClientState *nc)
+{
+    TAPState *s = DO_UPCAST(TAPState, nc, nc);
+    int ret;
+
+    if (s->enabled) {
+        return 0;
+    } else {
+        ret = tap_fd_enable(s->fd);
+        if (ret == 0) {
+            s->enabled = true;
+            tap_update_fd_handler(s);
+        }
+        return ret;
+    }
+}
+
+int tap_disable(NetClientState *nc)
+{
+    TAPState *s = DO_UPCAST(TAPState, nc, nc);
+    int ret;
+
+    if (s->enabled == 0) {
+        return 0;
+    } else {
+        ret = tap_fd_disable(s->fd);
+        if (ret == 0) {
+            qemu_purge_queued_packets(nc);
+            s->enabled = false;
+            tap_update_fd_handler(s);
+        }
+        return ret;
+    }
+}