[Qemu-devel] [PATCH for-2.4] net-hub: Drop can_receive

[Fam Zheng]

It returns true as long as there is another attached port. This is not
strictly necessary because even if there is only one port (the sender),
net_hub_port_receive could succeed with a NOP. So always deliver the
packets, instead of queuing them.

This fixes the possible hanging issue after net layer changed how
can_read is handled. That is, if net_hub_port_can_receive returned
false, the peer would disable the queue until it's explicitly flushed
(for example, a call to qemu_flush_queued_packets() in net_hub_add_port,
where net_hub_port_can_receive() would become true). This patch avoids
that complication.

Signed-off-by: Fam Zheng <address@hidden>
---
 net/hub.c | 20 --------------------
 1 file changed, 20 deletions(-)

diff --git a/net/hub.c b/net/hub.c
index 3047f12..65a8e09 100644
--- a/net/hub.c
+++ b/net/hub.c
@@ -87,25 +87,6 @@ static NetHub *net_hub_new(int id)
     return hub;
 }
 
-static int net_hub_port_can_receive(NetClientState *nc)
-{
-    NetHubPort *port;
-    NetHubPort *src_port = DO_UPCAST(NetHubPort, nc, nc);
-    NetHub *hub = src_port->hub;
-
-    QLIST_FOREACH(port, &hub->ports, next) {
-        if (port == src_port) {
-            continue;
-        }
-
-        if (qemu_can_send_packet(&port->nc)) {
-            return 1;
-        }
-    }
-
-    return 0;
-}
-
 static ssize_t net_hub_port_receive(NetClientState *nc,
                                     const uint8_t *buf, size_t len)
 {
@@ -132,7 +113,6 @@ static void net_hub_port_cleanup(NetClientState *nc)
 static NetClientInfo net_hub_port_info = {
     .type = NET_CLIENT_OPTIONS_KIND_HUBPORT,
     .size = sizeof(NetHubPort),
-    .can_receive = net_hub_port_can_receive,
     .receive = net_hub_port_receive,
     .receive_iov = net_hub_port_receive_iov,
     .cleanup = net_hub_port_cleanup,
-- 
2.4.4