[Qemu-devel] [PULL 28/41] vhost-user: keep vhost_net after a disconnection

[Michael S. Tsirkin]

From: Marc-André Lureau <marcandre.lur...@redhat.com>

Many code paths assume get_vhost_net() returns non-null.

Keep VhostUserState.vhost_net after a successful vhost_net_init(),
instead of freeing it in vhost_net_cleanup().

VhostUserState.vhost_net is thus freed before after being recreated or
on final vhost_user_cleanup() and there is no need to save the acked
features.

Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
Reviewed-by: Michael S. Tsirkin <m...@redhat.com>
Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
---
 hw/net/vhost_net.c |  1 -
 net/tap.c          |  1 +
 net/vhost-user.c   | 36 +++++++++++++++++++-----------------
 3 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index c11f69c..7b76591 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -378,7 +378,6 @@ void vhost_net_stop(VirtIODevice *dev, NetClientState *ncs,
 void vhost_net_cleanup(struct vhost_net *net)
 {
     vhost_dev_cleanup(&net->dev);
-    g_free(net);
 }
 
 int vhost_net_notify_migration_done(struct vhost_net *net, char* mac_addr)
diff --git a/net/tap.c b/net/tap.c
index 40a8c74..6abb962 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -312,6 +312,7 @@ static void tap_cleanup(NetClientState *nc)
 
     if (s->vhost_net) {
         vhost_net_cleanup(s->vhost_net);
+        g_free(s->vhost_net);
         s->vhost_net = NULL;
     }
 
diff --git a/net/vhost-user.c b/net/vhost-user.c
index 2cac32e..d2a984d 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -45,11 +45,6 @@ uint64_t vhost_user_get_acked_features(NetClientState *nc)
     return s->acked_features;
 }
 
-static int vhost_user_running(VhostUserState *s)
-{
-    return (s->vhost_net) ? 1 : 0;
-}
-
 static void vhost_user_stop(int queues, NetClientState *ncs[])
 {
     VhostUserState *s;
@@ -59,15 +54,14 @@ static void vhost_user_stop(int queues, NetClientState 
*ncs[])
         assert(ncs[i]->info->type == NET_CLIENT_DRIVER_VHOST_USER);
 
         s = DO_UPCAST(VhostUserState, nc, ncs[i]);
-        if (!vhost_user_running(s)) {
-            continue;
-        }
 
         if (s->vhost_net) {
             /* save acked features */
-            s->acked_features = vhost_net_get_acked_features(s->vhost_net);
+            uint64_t features = vhost_net_get_acked_features(s->vhost_net);
+            if (features) {
+                s->acked_features = features;
+            }
             vhost_net_cleanup(s->vhost_net);
-            s->vhost_net = NULL;
         }
     }
 }
@@ -75,6 +69,7 @@ static void vhost_user_stop(int queues, NetClientState *ncs[])
 static int vhost_user_start(int queues, NetClientState *ncs[])
 {
     VhostNetOptions options;
+    struct vhost_net *net = NULL;
     VhostUserState *s;
     int max_queues;
     int i;
@@ -85,33 +80,39 @@ static int vhost_user_start(int queues, NetClientState 
*ncs[])
         assert(ncs[i]->info->type == NET_CLIENT_DRIVER_VHOST_USER);
 
         s = DO_UPCAST(VhostUserState, nc, ncs[i]);
-        if (vhost_user_running(s)) {
-            continue;
-        }
 
         options.net_backend = ncs[i];
         options.opaque      = s->chr;
         options.busyloop_timeout = 0;
-        s->vhost_net = vhost_net_init(&options);
-        if (!s->vhost_net) {
+        net = vhost_net_init(&options);
+        if (!net) {
             error_report("failed to init vhost_net for queue %d", i);
             goto err;
         }
 
         if (i == 0) {
-            max_queues = vhost_net_get_max_queues(s->vhost_net);
+            max_queues = vhost_net_get_max_queues(net);
             if (queues > max_queues) {
                 error_report("you are asking more queues than supported: %d",
                              max_queues);
                 goto err;
             }
         }
+
+        if (s->vhost_net) {
+            vhost_net_cleanup(s->vhost_net);
+            g_free(s->vhost_net);
+        }
+        s->vhost_net = net;
     }
 
     return 0;
 
 err:
-    vhost_user_stop(i + 1, ncs);
+    if (net) {
+        vhost_net_cleanup(net);
+    }
+    vhost_user_stop(i, ncs);
     return -1;
 }
 
@@ -150,6 +151,7 @@ static void vhost_user_cleanup(NetClientState *nc)
 
     if (s->vhost_net) {
         vhost_net_cleanup(s->vhost_net);
+        g_free(s->vhost_net);
         s->vhost_net = NULL;
     }
     if (s->chr) {
-- 
MST