udp: Allow UDP flows to be prematurely closed

Unlike TCP, UDP has no in-band signalling for the end of a flow.  So the
only way we remove flows is on a timer if they have no activity for 180s.

However, we've started to investigate some error conditions in which we
want to prematurely abort / abandon a UDP flow.  We can call
udp_flow_close(), which will make the flow inert (sockets closed, no epoll
events, can't be looked up in hash).  However it will still wait 3 minutes
to clear away the stale entry.

Clean this up by adding an explicit 'closed' flag which will cause a flow
to be more promptly cleaned up.  We also publish udp_flow_close() so it
can be called from other places to abort UDP flows().

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/flow.c b/flow.c
index a00e01d..f2de041 100644
--- a/flow.c
+++ b/flow.c
@@ -832,7 +832,8 @@ void flow_defer_handler(const struct ctx *c, const struct timespec *now)
 				closed = icmp_ping_timer(c, &flow->ping, now);
 			break;
 		case FLOW_UDP:
-			if (timer)
+			closed = udp_flow_defer(&flow->udp);
+			if (!closed && timer)
 				closed = udp_flow_timer(c, &flow->udp, now);
 			break;
 		default: