[PATCH] virtio-serial-bus: do cleanup on the error path in realize() to avoid memleaks

[Pan Nengyuan]

port->bh forgot to delete on the error path, this patch add it to fix memleaks. 
It's easy to reproduce as follow(add a same nr port):
    {'execute': 'device_add', 'arguments': {'id': 'virtio_serial_pci0', 
'driver': 'virtio-serial-pci', 'bus': 'pci.0', 'addr': '0x5'}, 'id': 'yVkZcGgV'}
    {'execute': 'device_add', 'arguments': {'id': 'port1', 'driver': 
'virtserialport', 'name': 'port1', 'chardev': 'channel1', 'bus': 
'virtio_serial_pci0.0', 'nr': 1}, 'id': '3dXdUgJA'}
    {'execute': 'device_add', 'arguments': {'id': 'port2', 'driver': 
'virtserialport', 'name': 'port2', 'chardev': 'channel2', 'bus': 
'virtio_serial_pci0.0', 'nr': 1}, 'id': 'qLzcCkob'}
    {'execute': 'device_add', 'arguments': {'id': 'port2', 'driver': 
'virtserialport', 'name': 'port2', 'chardev': 'channel2', 'bus': 
'virtio_serial_pci0.0', 'nr': 2}, 'id': 'qLzcCkob'}

The leak stack:
Direct leak of 40 byte(s) in 1 object(s) allocated from:
    #0 0x7f04a8008ae8 in __interceptor_malloc (/lib64/libasan.so.5+0xefae8)
    #1 0x7f04a73cf1d5 in g_malloc (/lib64/libglib-2.0.so.0+0x531d5)
    #2 0x56273eaee484 in aio_bh_new /mnt/sdb/backup/qemu/util/async.c:125
    #3 0x56273eafe9a8 in qemu_bh_new /mnt/sdb/backup/qemu/util/main-loop.c:532
    #4 0x56273d52e62e in virtser_port_device_realize 
/mnt/sdb/backup/qemu/hw/char/virtio-serial-bus.c:946
    #5 0x56273dcc5040 in device_set_realized 
/mnt/sdb/backup/qemu/hw/core/qdev.c:891
    #6 0x56273e5ebbce in property_set_bool 
/mnt/sdb/backup/qemu/qom/object.c:2238
    #7 0x56273e5e5a9c in object_property_set 
/mnt/sdb/backup/qemu/qom/object.c:1324
    #8 0x56273e5ef5f8 in object_property_set_qobject 
/mnt/sdb/backup/qemu/qom/qom-qobject.c:26
    #9 0x56273e5e5e6a in object_property_set_bool 
/mnt/sdb/backup/qemu/qom/object.c:1390
    #10 0x56273daa40de in qdev_device_add 
/mnt/sdb/backup/qemu/qdev-monitor.c:680
    #11 0x56273daa53e9 in qmp_device_add /mnt/sdb/backup/qemu/qdev-monitor.c:805

Reported-by: Euler Robot <euler.ro...@huawei.com>
Signed-off-by: Pan Nengyuan <pannengy...@huawei.com>
---
 hw/char/virtio-serial-bus.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
index 941ed5aca9..563b845f71 100644
--- a/hw/char/virtio-serial-bus.c
+++ b/hw/char/virtio-serial-bus.c
@@ -957,13 +957,13 @@ static void virtser_port_device_realize(DeviceState *dev, 
Error **errp)
     if (find_port_by_id(port->vser, port->id)) {
         error_setg(errp, "virtio-serial-bus: A port already exists at id %u",
                    port->id);
-        return;
+        goto fail;
     }
 
     if (port->name != NULL && find_port_by_name(port->name)) {
         error_setg(errp, "virtio-serial-bus: A port already exists by name %s",
                    port->name);
-        return;
+        goto fail;
     }
 
     if (port->id == VIRTIO_CONSOLE_BAD_ID) {
@@ -974,7 +974,7 @@ static void virtser_port_device_realize(DeviceState *dev, 
Error **errp)
             if (port->id == VIRTIO_CONSOLE_BAD_ID) {
                 error_setg(errp, "virtio-serial-bus: Maximum port limit for "
                                  "this device reached");
-                return;
+                goto fail;
             }
         }
     }
@@ -983,16 +983,20 @@ static void virtser_port_device_realize(DeviceState *dev, 
Error **errp)
     if (port->id >= max_nr_ports) {
         error_setg(errp, "virtio-serial-bus: Out-of-range port id specified, "
                          "max. allowed: %u", max_nr_ports - 1);
-        return;
+        goto fail;
     }
 
     vsc->realize(dev, &err);
     if (err != NULL) {
         error_propagate(errp, err);
-        return;
+        goto fail;
     }
 
     port->elem = NULL;
+    return;
+
+fail:
+    qemu_bh_delete(port->bh);
 }
 
 static void virtser_port_device_plug(HotplugHandler *hotplug_dev,
-- 
2.18.2