In the splnet times, netgraph was functional and synchronous. Nowadays,

an item may be queued and processed later. While this is OK for mbufs,
this is a problem for control messages.

In the framework:
- Add optional callback function pointer to an item. When item gets
  applied the callback is executed from ng_apply_item().
- Add new flag NG_PROGRESS. If this flag is supplied, then return
  EINPROGRESS instead of 0 in case if item failed to deliver
  synchronously and was queued.
- Honor NG_PROGRESS in ng_snd_item().

In ng_socket:
- When userland sends control message add callback to the item.
- If ng_snd_item() returns EINPROGRESS, then sleep.

This change fixes possible races in ngctl(8) scripts.

Reviewed by:	julian
Approved by:	re (scottl)

1 files changed, 2 insertions, 0 deletions

diff --git a/sys/netgraph/ng_socketvar.h b/sys/netgraph/ng_socketvar.h
index a539bb5..3cf8103 100644
--- a/sys/netgraph/ng_socketvar.h
+++ b/sys/netgraph/ng_socketvar.h
@@ -59,6 +59,8 @@ struct ngsock {
 	struct ngpcb	*ctlsock;	/* optional control socket */
 	int    flags;
 	int    refs;
+	struct mtx	mtx;		/* mtx to wait on */
+	int		error;		/* place to store error */
 };
 #define	NGS_FLAG_NOLINGER	1	/* close with last hook */