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>

1 files changed, 16 insertions, 0 deletions

diff --git a/net/tap.c b/net/tap.c
index 672b0ee..e42c555 100644
--- 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;