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[Qemu-devel] [PATCH] fix qemu_flush_queued_packets() in presence of a hu
From: |
Luigi Rizzo |
Subject: |
[Qemu-devel] [PATCH] fix qemu_flush_queued_packets() in presence of a hub |
Date: |
Tue, 22 Jan 2013 07:54:20 +0100 |
User-agent: |
Mutt/1.4.2.3i |
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 <address@hidden>
net/hub.c | 13 +++++++++++++
net/hub.h | 1 +
net/net.c | 6 ++++++
diff --git a/net/hub.c b/net/hub.c
index a24c9d1..08f95d0 100644
--- a/net/hub.c
+++ b/net/hub.c
@@ -338,3 +338,16 @@ 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 816c987..8caa368 100644
--- a/net/net.c
+++ b/net/net.c
@@ -355,6 +355,12 @@ 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).