[Qemu-devel] [PATCH] net: Flush queued packets when guest resumes

[Fam Zheng <famz@redhat.com>]

Since commit 6e99c63 "net/socket: Drop net_socket_can_send" and friends,
net queues need to be explicitly flushed after qemu_can_send_packet()
returns false, because the netdev side will disable the polling of fd.

This fixes the case of "cont" after "stop" (or migration), i.e.
vm_running changes to true, by listening to vm state changes.

Signed-off-by: Fam Zheng <famz@redhat.com>
---
 include/net/net.h |  2 ++
 net/net.c         | 14 +++++++++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/include/net/net.h b/include/net/net.h
index 6a6cbef..619a6e1 100644
--- a/include/net/net.h
+++ b/include/net/net.h
@@ -8,6 +8,7 @@
 #include "net/queue.h"
 #include "migration/vmstate.h"
 #include "qapi-types.h"
+#include "sysemu/sysemu.h"
 
 #define MAX_QUEUE_NUM 1024
 
@@ -92,6 +93,7 @@ struct NetClientState {
     NetClientDestructor *destructor;
     unsigned int queue_index;
     unsigned rxfilter_notify_enabled:1;
+    VMChangeStateEntry *vmcse;
 };
 
 typedef struct NICState {
diff --git a/net/net.c b/net/net.c
index 6ff7fec..edfa6a0 100644
--- a/net/net.c
+++ b/net/net.c
@@ -43,7 +43,6 @@
 #include "qapi-visit.h"
 #include "qapi/opts-visitor.h"
 #include "qapi/dealloc-visitor.h"
-#include "sysemu/sysemu.h"
 
 /* Net bridge is currently not supported for W32. */
 #if !defined(_WIN32)
@@ -263,6 +262,16 @@ static void qemu_net_client_destructor(NetClientState *nc)
     g_free(nc);
 }
 
+static void qemu_net_client_handle_vmstate(void *opaque,
+                                           int running,
+                                           RunState state)
+{
+    NetClientState *nc = opaque;
+    if (running && qemu_can_send_packet(nc) && nc->peer) {
+        qemu_flush_queued_packets(nc->peer);
+    }
+}
+
 static void qemu_net_client_setup(NetClientState *nc,
                                   NetClientInfo *info,
                                   NetClientState *peer,
@@ -287,6 +296,8 @@ static void qemu_net_client_setup(NetClientState *nc,
 
     nc->incoming_queue = qemu_new_net_queue(nc);
     nc->destructor = destructor;
+    nc->vmcse = qemu_add_vm_change_state_handler(qemu_net_client_handle_vmstate,
+                                                 nc);
 }
 
 NetClientState *qemu_new_net_client(NetClientInfo *info,
@@ -395,6 +406,7 @@ void qemu_del_net_client(NetClientState *nc)
                                           MAX_QUEUE_NUM);
     assert(queues != 0);
 
+    qemu_del_vm_change_state_handler(nc->vmcse);
     /* If there is a peer NIC, delete and cleanup client, but do not free. */
     if (nc->peer && nc->peer->info->type == NET_CLIENT_OPTIONS_KIND_NIC) {
         NICState *nic = qemu_get_nic(nc->peer);
-- 
2.4.3