monitor: Make client_migrate_info synchronous

Live migration with spice works like this today:

  (1) client_migrate_info monitor cmd
  (2) spice server notifies client, client connects to target host.
  (3) qemu waits until spice client connect is finished.
  (4) send over vmstate (i.e. main part of live migration).
  (5) spice handover to target host.

(3) is implemented by making client_migrate_info a async monitor
command.  This is the only async monitor command we have.

The original reason to implement this dance was that qemu did not accept
new tcp connections while the incoming migration was running, so (2) and
(4) could not be done in parallel.  That issue was fixed long ago though.
Qemu version 1.3.0 (released Dec 2012) and newer happily accept tcp
connects while the incoming migration runs.

Time to drop step (3).  This patch does exactly that, by making the
monitor command synchronous and removing the code needed to handle the
async monitor command in ui/spice-core.c

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

hmp-commands.hx

@@ -998,8 +998,7 @@ ETEXI
         .params     = "protocol hostname port tls-port cert-subject",
         .help       = "send migration info to spice/vnc client",
         .user_print = monitor_user_noop,
-        .mhandler.cmd_async = client_migrate_info,
+        .mhandler.cmd_new = client_migrate_info,
-        .flags      = MONITOR_CMD_ASYNC,
     },
 
 STEXI

include/ui/qemu-spice.h

@@ -42,8 +42,7 @@ int qemu_spice_set_passwd(const char *passwd,
                           bool fail_if_connected, bool disconnect_if_connected);
 int qemu_spice_set_pw_expire(time_t expires);
 int qemu_spice_migrate_info(const char *hostname, int port, int tls_port,
-                            const char *subject,
+                            const char *subject);
-                            MonitorCompletion cb, void *opaque);
 
 CharDriverState *qemu_chr_open_spice_vmc(const char *type);
 #if SPICE_SERVER_VERSION >= 0x000c02
@@ -70,10 +69,8 @@ static inline int qemu_spice_set_pw_expire(time_t expires)
     return -1;
 }
 static inline int qemu_spice_migrate_info(const char *h, int p, int t,
-                                          const char *s,
+                                          const char *s)
-                                          MonitorCompletion cb, void *opaque)
 {
-    cb(opaque, NULL);
     return -1;
 }
 

monitor.c

@@ -1086,7 +1086,7 @@ static void hmp_info_trace_events(Monitor *mon, const QDict *qdict)
 }
 
 static int client_migrate_info(Monitor *mon, const QDict *qdict,
-                               MonitorCompletion cb, void *opaque)
+                               QObject **ret_data)
 {
     const char *protocol = qdict_get_str(qdict, "protocol");
     const char *hostname = qdict_get_str(qdict, "hostname");
@@ -1108,8 +1108,7 @@ static int client_migrate_info(Monitor *mon, const QDict *qdict,
             return -1;
         }
 
-        ret = qemu_spice_migrate_info(hostname, port, tls_port, subject,
+        ret = qemu_spice_migrate_info(hostname, port, tls_port, subject);
-                                      cb, opaque);
         if (ret != 0) {
             qerror_report(QERR_UNDEFINED_ERROR);
             return -1;

qmp-commands.hx

@@ -785,8 +785,7 @@ EQMP
         .args_type  = "protocol:s,hostname:s,port:i?,tls-port:i?,cert-subject:s?",
         .params     = "protocol hostname port tls-port cert-subject",
         .help       = "send migration info to spice/vnc client",
-        .mhandler.cmd_async = client_migrate_info,
+        .mhandler.cmd_new = client_migrate_info,
-        .flags      = MONITOR_CMD_ASYNC,
     },
 
 SQMP

ui/spice-core.c

@@ -273,14 +273,6 @@ static SpiceCoreInterface core_interface = {
     .channel_event      = channel_event,
 };
 
-typedef struct SpiceMigration {
-    SpiceMigrateInstance sin;
-    struct {
-        MonitorCompletion *cb;
-        void *opaque;
-    } connect_complete;
-} SpiceMigration;
-
 static void migrate_connect_complete_cb(SpiceMigrateInstance *sin);
 static void migrate_end_complete_cb(SpiceMigrateInstance *sin);
 
@@ -293,15 +285,11 @@ static const SpiceMigrateInterface migrate_interface = {
     .migrate_end_complete = migrate_end_complete_cb,
 };
 
-static SpiceMigration spice_migrate;
+static SpiceMigrateInstance spice_migrate;
 
 static void migrate_connect_complete_cb(SpiceMigrateInstance *sin)
 {
-    SpiceMigration *sm = container_of(sin, SpiceMigration, sin);
+    /* nothing, but libspice-server expects this cb being present. */
-    if (sm->connect_complete.cb) {
-        sm->connect_complete.cb(sm->connect_complete.opaque, NULL);
-    }
-    sm->connect_complete.cb = NULL;
 }
 
 static void migrate_end_complete_cb(SpiceMigrateInstance *sin)
@@ -585,13 +573,10 @@ static void migration_state_notifier(Notifier *notifier, void *data)
 }
 
 int qemu_spice_migrate_info(const char *hostname, int port, int tls_port,
-                            const char *subject,
+                            const char *subject)
-                            MonitorCompletion *cb, void *opaque)
 {
     int ret;
 
-    spice_migrate.connect_complete.cb = cb;
-    spice_migrate.connect_complete.opaque = opaque;
     ret = spice_server_migrate_connect(spice_server, hostname,
                                        port, tls_port, subject);
     spice_have_target_host = true;
@@ -812,9 +797,8 @@ void qemu_spice_init(void)
 
     migration_state.notify = migration_state_notifier;
     add_migration_state_change_notifier(&migration_state);
-    spice_migrate.sin.base.sif = &migrate_interface.base;
+    spice_migrate.base.sif = &migrate_interface.base;
-    spice_migrate.connect_complete.cb = NULL;
+    qemu_spice_add_interface(&spice_migrate.base);
-    qemu_spice_add_interface(&spice_migrate.sin.base);
 
     qemu_spice_input_init();
     qemu_spice_audio_init();