virtio-serial: create a linked list of all active devices

To ensure two virtserialports don't get added to the system with the
same 'name' parameter, we need to access all the ports on all the
devices added, and compare the names.

We currently don't have a list of all VirtIOSerial devices added to the
system.  This commit adds a simple linked list in which devices are put
when they're initialized, and removed when they go away.
Signed-off-by: NAmit Shah <amit.shah@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>

hw/char/virtio-serial-bus.c

@@ -26,6 +26,10 @@
 #include "hw/virtio/virtio-serial.h"
 #include "hw/virtio/virtio-access.h"
 
+struct VirtIOSerialDevices {
+    QLIST_HEAD(, VirtIOSerial) devices;
+} vserdevices;
+
 static VirtIOSerialPort *find_port_by_id(VirtIOSerial *vser, uint32_t id)
 {
     VirtIOSerialPort *port;
@@ -983,6 +987,8 @@ static void virtio_serial_device_realize(DeviceState *dev, Error **errp)
      */
     register_savevm(dev, "virtio-console", -1, 3, virtio_serial_save,
                     virtio_serial_load, vser);
+
+    QLIST_INSERT_HEAD(&vserdevices.devices, vser, next);
 }
 
 static void virtio_serial_port_class_init(ObjectClass *klass, void *data)
@@ -1011,6 +1017,8 @@ static void virtio_serial_device_unrealize(DeviceState *dev, Error **errp)
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
     VirtIOSerial *vser = VIRTIO_SERIAL(dev);
 
+    QLIST_REMOVE(vser, next);
+
     unregister_savevm(dev, "virtio-console", vser);
 
     g_free(vser->ivqs);
@@ -1035,6 +1043,8 @@ static void virtio_serial_class_init(ObjectClass *klass, void *data)
     DeviceClass *dc = DEVICE_CLASS(klass);
     VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
 
+    QLIST_INIT(&vserdevices.devices);
+
     dc->props = virtio_serial_properties;
     set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
     vdc->realize = virtio_serial_device_realize;

include/hw/virtio/virtio-serial.h

@@ -202,6 +202,8 @@ struct VirtIOSerial {
 
     QTAILQ_HEAD(, VirtIOSerialPort) ports;
 
+    QLIST_ENTRY(VirtIOSerial) next;
+
     /* bitmap for identifying active ports */
     uint32_t *ports_map;