[Qemu-devel] [PATCH 2/3] net: Flush queues when runstate changes back to running

[zhanghailiang]

When the runstate changes back to running, we definitely need to flush
queues to get packets flowing again.

Here we implement this in the net layer:
(1) add a member 'VMChangeStateEntry *vmstate' to struct NICState,
Which will listen for VM runstate changes.
(2) Register a handler function for VMstate change.
When vm changes back to running, we flush all queues in the callback function.

Signed-off-by: zhanghailiang <zhang.zhanghaili...@huawei.com>
---
 include/net/net.h |  1 +
 net/net.c         | 26 ++++++++++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/include/net/net.h b/include/net/net.h
index 312f728..a294277 100644
--- a/include/net/net.h
+++ b/include/net/net.h
@@ -97,6 +97,7 @@ typedef struct NICState {
     NICConf *conf;
     void *opaque;
     bool peer_deleted;
+    VMChangeStateEntry *vmstate;
 } NICState;
 
 NetClientState *qemu_find_netdev(const char *id);
diff --git a/net/net.c b/net/net.c
index 5bb2821..506e58f 100644
--- a/net/net.c
+++ b/net/net.c
@@ -242,6 +242,29 @@ NetClientState *qemu_new_net_client(NetClientInfo *info,
     return nc;
 }
 
+static void nic_vmstate_change_handler(void *opaque,
+                                       int running,
+                                       RunState state)
+{
+    NICState *nic = opaque;
+    NetClientState *nc;
+    int i, queues;
+
+    if (!running) {
+        return;
+    }
+
+    queues =  MAX(1, nic->conf->peers.queues);
+    for (i = 0; i < queues; i++) {
+        nc = &nic->ncs[i];
+        if (nc->receive_disabled
+            || (nc->info->can_receive && !nc->info->can_receive(nc))) {
+            continue;
+        }
+        qemu_flush_queued_packets(nc);
+    }
+}
+
 NICState *qemu_new_nic(NetClientInfo *info,
                        NICConf *conf,
                        const char *model,
@@ -259,6 +282,8 @@ NICState *qemu_new_nic(NetClientInfo *info,
     nic->ncs = (void *)nic + info->size;
     nic->conf = conf;
     nic->opaque = opaque;
+    nic->vmstate = qemu_add_vm_change_state_handler(nic_vmstate_change_handler,
+                                                    nic);
 
     for (i = 0; i < queues; i++) {
         qemu_net_client_setup(&nic->ncs[i], info, peers[i], model, name,
@@ -379,6 +404,7 @@ void qemu_del_nic(NICState *nic)
         qemu_free_net_client(nc);
     }
 
+    qemu_del_vm_change_state_handler(nic->vmstate);
     g_free(nic);
 }
 
-- 
1.7.12.4