tap: invoke downscript when we exit abnormally

Right now, downscript is not invoked reliably.  If you execute 'quit' from the
monitor, it won't be invoked.

This fixes that by converting tap to use an exit_notifier to execute the
downscript.  In this case, allowing an exit notifier to include state is
critically important for the conversion.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/net/tap.c b/net/tap.c
index 672b0ee0b49c226d41f9dc44ce6e8ac8706b41a9..e42c555029db931ab39691d4600a1d6a0d5e76bc 100644 (file)
--- a/net/tap.c
+++ b/net/tap.c
@@ -53,6 +53,7 @@ typedef struct TAPState {
     char down_script[1024];
     char down_script_arg[128];
     uint8_t buf[TAP_BUFSIZE];
+    Notifier exit_notifier;
     unsigned int read_poll : 1;
     unsigned int write_poll : 1;
     unsigned int has_vnet_hdr : 1;
@@ -261,6 +262,19 @@ static void tap_cleanup(VLANClientState *nc)
     tap_read_poll(s, 0);
     tap_write_poll(s, 0);
     close(s->fd);
+    exit_notifier_remove(&s->exit_notifier);
+}
+
+/* Instead of exiting gracefully, we're exiting because someone called
+ * exit(), make sure to invoke down script at least
+ */
+static void tap_cleanup_at_exit(Notifier *notifier)
+{
+    TAPState *s = container_of(notifier, TAPState, exit_notifier);
+
+    if (s->down_script[0]) {
+        launch_script(s->down_script, s->down_script_arg, s->fd);
+    }
 }
 
 static void tap_poll(VLANClientState *nc, bool enable)
@@ -299,6 +313,8 @@ static TAPState *net_tap_fd_init(VLANState *vlan,
     s->has_vnet_hdr = vnet_hdr != 0;
     s->using_vnet_hdr = 0;
     s->has_ufo = tap_probe_has_ufo(s->fd);
+    s->exit_notifier.notify = tap_cleanup_at_exit;
+    exit_notifier_add(&s->exit_notifier);
     tap_set_offload(&s->nc, 0, 0, 0, 0, 0);
     tap_read_poll(s, 1);
     return s;