[Qemu-devel] [PATCH v1 10/14] net: make netclient re-entrant with refcnt

[Liu Ping Fan <qemulist@gmail.com>]

From: Liu Ping Fan <pingfank@linux.vnet.ibm.com>

With refcnt, NetClientState's user can run agaist deleter.

Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
---
 hw/qdev-properties-system.c |   14 +++++++++++++
 include/net/net.h           |    3 ++
 net/hub.c                   |    3 ++
 net/net.c                   |   46 ++++++++++++++++++++++++++++++++++++++++--
 net/slirp.c                 |    3 +-
 5 files changed, 65 insertions(+), 4 deletions(-)

diff --git a/hw/qdev-properties-system.c b/hw/qdev-properties-system.c
index ce3af22..14c6d49 100644
--- a/hw/qdev-properties-system.c
+++ b/hw/qdev-properties-system.c
@@ -301,6 +301,7 @@ static void set_vlan(Object *obj, Visitor *v, void *opaque,
         return;
     }
 
+    /* inc ref, released when unset property */
     hubport = net_hub_port_find(id);
     if (!hubport) {
         error_set(errp, QERR_INVALID_PARAMETER_VALUE,
@@ -310,11 +311,24 @@ static void set_vlan(Object *obj, Visitor *v, void *opaque,
     *ptr = hubport;
 }
 
+static void release_vlan(Object *obj, const char *name, void *opaque)
+{
+    DeviceState *dev = DEVICE(obj);
+    Property *prop = opaque;
+    NICPeers *peers_ptr = qdev_get_prop_ptr(dev, prop);
+    NetClientState **ptr = &peers_ptr->ncs[0];
+
+    if (*ptr) {
+        netclient_unref(*ptr);
+    }
+}
+
 PropertyInfo qdev_prop_vlan = {
     .name  = "vlan",
     .print = print_vlan,
     .get   = get_vlan,
     .set   = set_vlan,
+    .release = release_vlan,
 };
 
 int qdev_prop_set_drive(DeviceState *dev, const char *name,
diff --git a/include/net/net.h b/include/net/net.h
index 54f91ea..ef4137d 100644
--- a/include/net/net.h
+++ b/include/net/net.h
@@ -61,6 +61,7 @@ typedef struct NetClientInfo {
 } NetClientInfo;
 
 struct NetClientState {
+    int ref;
     NetClientInfo *info;
     int link_down;
     QTAILQ_ENTRY(NetClientState) next;
@@ -89,6 +90,8 @@ typedef struct NICState {
 NetClientState *qemu_find_netdev(const char *id);
 int qemu_find_net_clients_except(const char *id, NetClientState **ncs,
                                  NetClientOptionsKind type, int max);
+void netclient_ref(NetClientState *nc);
+void netclient_unref(NetClientState *nc);
 NetClientState *qemu_new_net_client(NetClientInfo *info,
                                     NetClientState *peer,
                                     const char *model,
diff --git a/net/hub.c b/net/hub.c
index 812a6dc..2970f8e 100644
--- a/net/hub.c
+++ b/net/hub.c
@@ -212,6 +212,7 @@ NetClientState *net_hub_find_client_by_name(int hub_id, const char *name)
                 peer = port->nc.peer;
 
                 if (peer && strcmp(peer->name, name) == 0) {
+                    netclient_ref(peer);
                     qemu_mutex_unlock(&hub->ports_lock);
                     return peer;
                 }
@@ -237,6 +238,7 @@ NetClientState *net_hub_port_find(int hub_id)
             QLIST_FOREACH(port, &hub->ports, next) {
                 nc = port->nc.peer;
                 if (!nc) {
+                    netclient_ref(&port->nc);
                     qemu_mutex_unlock(&hub->ports_lock);
                     return &(port->nc);
                 }
@@ -247,6 +249,7 @@ NetClientState *net_hub_port_find(int hub_id)
     }
 
     nc = net_hub_add_port(hub_id, NULL);
+    netclient_ref(nc);
     return nc;
 }
 
diff --git a/net/net.c b/net/net.c
index 7619762..ac859ff 100644
--- a/net/net.c
+++ b/net/net.c
@@ -45,6 +45,7 @@
 # define CONFIG_NET_BRIDGE
 #endif
 
+static QemuMutex net_clients_lock;
 static QTAILQ_HEAD(, NetClientState) net_clients;
 
 int default_net = 1;
@@ -166,6 +167,7 @@ static char *assign_name(NetClientState *nc1, const char *model)
     char buf[256];
     int id = 0;
 
+    qemu_mutex_lock(&net_clients_lock);
     QTAILQ_FOREACH(nc, &net_clients, next) {
         if (nc == nc1) {
             continue;
@@ -176,6 +178,7 @@ static char *assign_name(NetClientState *nc1, const char *model)
             id++;
         }
     }
+    qemu_mutex_unlock(&net_clients_lock);
 
     snprintf(buf, sizeof(buf), "%s.%d", model, id);
 
@@ -206,9 +209,13 @@ static void qemu_net_client_setup(NetClientState *nc,
         assert(!peer->peer);
         nc->peer = peer;
         peer->peer = nc;
+        netclient_ref(peer);
+        netclient_ref(nc);
     }
     qemu_mutex_init(&nc->peer_lock);
+    qemu_mutex_lock(&net_clients_lock);
     QTAILQ_INSERT_TAIL(&net_clients, nc, next);
+    qemu_mutex_unlock(&net_clients_lock);
 
     nc->send_queue = qemu_new_net_queue(nc);
     nc->destructor = destructor;
@@ -224,6 +231,7 @@ NetClientState *qemu_new_net_client(NetClientInfo *info,
     assert(info->size >= sizeof(NetClientState));
 
     nc = g_malloc0(info->size);
+    netclient_ref(nc);
     qemu_net_client_setup(nc, info, peer, model, name,
                           qemu_net_client_destructor);
 
@@ -284,7 +292,9 @@ void *qemu_get_nic_opaque(NetClientState *nc)
 
 static void qemu_cleanup_net_client(NetClientState *nc)
 {
+    qemu_mutex_lock(&net_clients_lock);
     QTAILQ_REMOVE(&net_clients, nc, next);
+    qemu_mutex_unlock(&net_clients_lock);
 
     if (nc->info->cleanup) {
         nc->info->cleanup(nc);
@@ -306,6 +316,18 @@ static void qemu_free_net_client(NetClientState *nc)
     }
 }
 
+void netclient_ref(NetClientState *nc)
+{
+    __sync_add_and_fetch(&nc->ref, 1);
+}
+
+void netclient_unref(NetClientState *nc)
+{
+    if (__sync_sub_and_fetch(&nc->ref, 1) == 0) {
+        qemu_free_net_client(nc);
+    }
+}
+
 /* elimate the reference and sync with exit of rx/tx action.
  * And flush out peer's queue.
  */
@@ -334,8 +356,10 @@ static void qemu_net_client_detach_flush(NetClientState *nc)
     nc->peer = NULL;
     if (peer) {
         qemu_net_queue_purge(peer->send_queue, nc);
+        netclient_unref(peer);
     }
     qemu_mutex_unlock(&nc->peer_lock);
+    netclient_unref(nc);
 }
 
 void qemu_del_net_client(NetClientState *nc)
@@ -381,7 +405,7 @@ void qemu_del_net_client(NetClientState *nc)
     for (i = 0; i < queues; i++) {
         qemu_net_client_detach_flush(ncs[i]);
         qemu_cleanup_net_client(ncs[i]);
-        qemu_free_net_client(ncs[i]);
+        netclient_unref(ncs[i]);
     }
 }
 
@@ -392,7 +416,7 @@ void qemu_del_nic(NICState *nic)
     /* If this is a peer NIC and peer has already been deleted, free it now. */
     if (nic->peer_deleted) {
         for (i = 0; i < queues; i++) {
-            qemu_free_net_client(nic->pending_peer[i]);
+            netclient_unref(nic->pending_peer[i]);
         }
     }
 
@@ -401,7 +425,7 @@ void qemu_del_nic(NICState *nic)
 
         qemu_net_client_detach_flush(nc);
         qemu_cleanup_net_client(nc);
-        qemu_free_net_client(nc);
+        netclient_unref(nc);
     }
 
     g_free(nic->pending_peer);
@@ -412,6 +436,7 @@ void qemu_foreach_nic(qemu_nic_foreach func, void *opaque)
 {
     NetClientState *nc;
 
+    qemu_mutex_lock(&net_clients_lock);
     QTAILQ_FOREACH(nc, &net_clients, next) {
         if (nc->info->type == NET_CLIENT_OPTIONS_KIND_NIC) {
             if (nc->queue_index == 0) {
@@ -419,6 +444,7 @@ void qemu_foreach_nic(qemu_nic_foreach func, void *opaque)
             }
         }
     }
+    qemu_mutex_unlock(&net_clients_lock);
 }
 
 int qemu_can_send_packet_nolock(NetClientState *sender)
@@ -633,13 +659,17 @@ NetClientState *qemu_find_netdev(const char *id)
 {
     NetClientState *nc;
 
+    qemu_mutex_lock(&net_clients_lock);
     QTAILQ_FOREACH(nc, &net_clients, next) {
         if (nc->info->type == NET_CLIENT_OPTIONS_KIND_NIC)
             continue;
         if (!strcmp(nc->name, id)) {
+            netclient_ref(nc);
+            qemu_mutex_unlock(&net_clients_lock);
             return nc;
         }
     }
+    qemu_mutex_unlock(&net_clients_lock);
 
     return NULL;
 }
@@ -650,6 +680,7 @@ int qemu_find_net_clients_except(const char *id, NetClientState **ncs,
     NetClientState *nc;
     int ret = 0;
 
+    qemu_mutex_lock(&net_clients_lock);
     QTAILQ_FOREACH(nc, &net_clients, next) {
         if (nc->info->type == type) {
             continue;
@@ -661,6 +692,7 @@ int qemu_find_net_clients_except(const char *id, NetClientState **ncs,
             ret++;
         }
     }
+    qemu_mutex_unlock(&net_clients_lock);
 
     return ret;
 }
@@ -969,6 +1001,7 @@ void net_host_device_remove(Monitor *mon, const QDict *qdict)
         return;
     }
     qemu_del_net_client(nc);
+    netclient_unref(nc);
 }
 
 void netdev_add(QemuOpts *opts, Error **errp)
@@ -1024,6 +1057,7 @@ void qmp_netdev_del(const char *id, Error **errp)
     }
 
     qemu_del_net_client(nc);
+    netclient_unref(nc);
     qemu_opts_del(opts);
 }
 
@@ -1042,6 +1076,7 @@ void do_info_network(Monitor *mon, const QDict *qdict)
 
     net_hub_info(mon);
 
+    qemu_mutex_lock(&net_clients_lock);
     QTAILQ_FOREACH(nc, &net_clients, next) {
         peer = nc->peer;
         type = nc->info->type;
@@ -1059,6 +1094,7 @@ void do_info_network(Monitor *mon, const QDict *qdict)
             print_net_client(mon, peer);
         }
     }
+    qemu_mutex_unlock(&net_clients_lock);
 }
 
 void qmp_set_link(const char *name, bool up, Error **errp)
@@ -1112,6 +1148,7 @@ void net_cleanup(void)
             qemu_del_net_client(nc);
         }
     }
+    qemu_mutex_destroy(&net_clients_lock);
 }
 
 void net_check_clients(void)
@@ -1133,6 +1170,7 @@ void net_check_clients(void)
 
     net_hub_check_clients();
 
+    qemu_mutex_lock(&net_clients_lock);
     QTAILQ_FOREACH(nc, &net_clients, next) {
         if (!nc->peer) {
             fprintf(stderr, "Warning: %s %s has no peer\n",
@@ -1140,6 +1178,7 @@ void net_check_clients(void)
                     "nic" : "netdev", nc->name);
         }
     }
+    qemu_mutex_unlock(&net_clients_lock);
 
     /* Check that all NICs requested via -net nic actually got created.
      * NICs created via -device don't need to be checked here because
@@ -1197,6 +1236,7 @@ int net_init_clients(void)
 #endif
     }
 
+    qemu_mutex_init(&net_clients_lock);
     QTAILQ_INIT(&net_clients);
 
     if (qemu_opts_foreach(qemu_find_opts("netdev"), net_init_netdev, NULL, 1) == -1)
diff --git a/net/slirp.c b/net/slirp.c
index 4df550f..a6116d5 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -346,7 +346,7 @@ void net_slirp_hostfwd_remove(Monitor *mon, const QDict *qdict)
 
     err = slirp_remove_hostfwd(QTAILQ_FIRST(&slirp_stacks)->slirp, is_udp,
                                host_addr, host_port);
-
+    netclient_unref(&s->nc);
     monitor_printf(mon, "host forwarding rule for %s %s\n", src_str,
                    err ? "not found" : "removed");
     return;
@@ -437,6 +437,7 @@ void net_slirp_hostfwd_add(Monitor *mon, const QDict *qdict)
     }
     if (s) {
         slirp_hostfwd(s, redir_str, 0);
+        netclient_unref(&s->nc);
     }
 
 }
-- 
1.7.4.4