DESCRIPTION:
When frontend and backend are connected through a hub as below
(showing only one direction), and the frontend (or in general, all
output ports of the hub) cannot accept more traffic, the backend
queues packets in queue-A.
When the frontend (or in general, one output port) becomes ready again,
quemu tries to flush packets from queue-B, which is unfortunately empty.
e1000.0 --[queue B]-- hub0port0(hub)hub0port1 --[queue A]-- tap.0
To fix this i propose to introduce a new function net_hub_flush()
which is called when trying to flush a queue connected to a hub.
cheers
luigi
Signed-off-by: Luigi Rizzo ri...@iet.unipi.it
diff --git a/net/hub.c b/net/hub.c
index a24c9d1..df32074 100644
--- a/net/hub.c
+++ b/net/hub.c
@@ -338,3 +338,17 @@ void net_hub_check_clients(void)
}
}
}
+
+bool net_hub_flush(NetClientState *nc)
+{
+NetHubPort *port;
+NetHubPort *source_port = DO_UPCAST(NetHubPort, nc, nc);
+int ret = 0;
+
+QLIST_FOREACH(port, source_port-hub-ports, next) {
+if (port != source_port) {
+ret += qemu_net_queue_flush(port-nc.send_queue);
+}
+}
+return ret ? true : false;
+}
diff --git a/net/hub.h b/net/hub.h
index 583ada8..a625eff 100644
--- a/net/hub.h
+++ b/net/hub.h
@@ -21,5 +21,6 @@ NetClientState *net_hub_add_port(int hub_id, const char
*name);
NetClientState *net_hub_find_client_by_name(int hub_id, const char *name);
void net_hub_info(Monitor *mon);
void net_hub_check_clients(void);
+bool net_hub_flush(NetClientState *nc);
#endif /* NET_HUB_H */
diff --git a/net/net.c b/net/net.c
index 9806862..9489702 100644
--- a/net/net.c
+++ b/net/net.c
@@ -439,6 +439,12 @@ void qemu_flush_queued_packets(NetClientState *nc)
{
nc-receive_disabled = 0;
+if (nc-peer nc-peer-info-type == NET_CLIENT_OPTIONS_KIND_HUBPORT) {
+if (net_hub_flush(nc-peer)) {
+qemu_notify_event();
+}
+return;
+}
if (qemu_net_queue_flush(nc-send_queue)) {
/* We emptied the queue successfully, signal to the IO thread to repoll
* the file descriptor (for tap, for example).
