[PATCH V9 16/46] migration: simplify notifiers

[Steve Sistare <steven.sistare@oracle.com>]

Pass the callback function to add_migration_state_change_notifier so
that migration can initialize the notifier on add and clear it on
delete, which simplifies the call sites.  Also shorten the function
names.

No functional change.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 hw/net/virtio-net.c      |  6 +++---
 hw/vfio/migration.c      |  6 +++---
 include/migration/misc.h |  6 ++++--
 migration/migration.c    | 22 ++++++++++++++++------
 ui/spice-core.c          |  3 +--
 5 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index dd0d056..29af1a5 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -3443,8 +3443,8 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
         n->primary_listener.hide_device = failover_hide_primary_device;
         qatomic_set(&n->failover_primary_hidden, true);
         device_listener_register(&n->primary_listener);
-        n->migration_state.notify = virtio_net_migration_state_notifier;
-        add_migration_state_change_notifier(&n->migration_state);
+        migration_add_notifier(&n->migration_state,
+                               virtio_net_migration_state_notifier);
         n->host_features |= (1ULL << VIRTIO_NET_F_STANDBY);
     }
 
@@ -3607,7 +3607,7 @@ static void virtio_net_device_unrealize(DeviceState *dev)
     if (n->failover) {
         qobject_unref(n->primary_opts);
         device_listener_unregister(&n->primary_listener);
-        remove_migration_state_change_notifier(&n->migration_state);
+        migration_remove_notifier(&n->migration_state);
     } else {
         assert(n->primary_opts == NULL);
     }
diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c
index d6f9e29..5109124 100644
--- a/hw/vfio/migration.c
+++ b/hw/vfio/migration.c
@@ -839,8 +839,8 @@ static int vfio_migration_init(VFIODevice *vbasedev,
     migration->vm_state = qdev_add_vm_change_state_handler(vbasedev->dev,
                                                            vfio_vmstate_change,
                                                            vbasedev);
-    migration->migration_state.notify = vfio_migration_state_notifier;
-    add_migration_state_change_notifier(&migration->migration_state);
+    migration_add_notifier(&migration->migration_state,
+                           vfio_migration_state_notifier);
     return 0;
 
 err:
@@ -895,7 +895,7 @@ void vfio_migration_finalize(VFIODevice *vbasedev)
     if (vbasedev->migration) {
         VFIOMigration *migration = vbasedev->migration;
 
-        remove_migration_state_change_notifier(&migration->migration_state);
+        migration_remove_notifier(&migration->migration_state);
         qemu_del_vm_change_state_handler(migration->vm_state);
         unregister_savevm(VMSTATE_IF(vbasedev->dev), "vfio", vbasedev);
         vfio_migration_exit(vbasedev);
diff --git a/include/migration/misc.h b/include/migration/misc.h
index 71b6285..d4c2d7d 100644
--- a/include/migration/misc.h
+++ b/include/migration/misc.h
@@ -60,8 +60,10 @@ void migration_object_init(void);
 void migration_shutdown(void);
 bool migration_is_idle(void);
 bool migration_is_active(MigrationState *);
-void add_migration_state_change_notifier(Notifier *notify);
-void remove_migration_state_change_notifier(Notifier *notify);
+void migration_add_notifier(Notifier *notify,
+                            void (*func)(Notifier *notifier, void *data));
+void migration_remove_notifier(Notifier *notify);
+void migration_call_notifiers(MigrationState *s);
 bool migration_in_setup(MigrationState *);
 bool migration_has_finished(MigrationState *);
 bool migration_has_failed(MigrationState *);
diff --git a/migration/migration.c b/migration/migration.c
index 80b7d09..d7c6902 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1962,7 +1962,7 @@ static void migrate_fd_cleanup(MigrationState *s)
         /* It is used on info migrate.  We can't free it */
         error_report_err(error_copy(s->error));
     }
-    notifier_list_notify(&migration_state_notifiers, s);
+    migration_call_notifiers(s);
     block_cleanup_parameters(s);
     yank_unregister_instance(MIGRATION_YANK_INSTANCE);
 }
@@ -2057,14 +2057,24 @@ static void migrate_fd_cancel(MigrationState *s)
     }
 }
 
-void add_migration_state_change_notifier(Notifier *notify)
+void migration_add_notifier(Notifier *notify,
+                            void (*func)(Notifier *notifier, void *data))
 {
+    notify->notify = func;
     notifier_list_add(&migration_state_notifiers, notify);
 }
 
-void remove_migration_state_change_notifier(Notifier *notify)
+void migration_remove_notifier(Notifier *notify)
+{
+    if (notify->notify) {
+        notifier_remove(notify);
+        notify->notify = NULL;
+    }
+}
+
+void migration_call_notifiers(MigrationState *s)
 {
-    notifier_remove(notify);
+    notifier_list_notify(&migration_state_notifiers, s);
 }
 
 bool migration_in_setup(MigrationState *s)
@@ -3341,7 +3351,7 @@ static int postcopy_start(MigrationState *ms)
      * spice needs to trigger a transition now
      */
     ms->postcopy_after_devices = true;
-    notifier_list_notify(&migration_state_notifiers, ms);
+    migration_call_notifiers(ms);
 
     ms->downtime =  qemu_clock_get_ms(QEMU_CLOCK_REALTIME) - time_at_stop;
 
@@ -4378,7 +4388,7 @@ void migrate_fd_connect(MigrationState *s, Error *error_in)
         rate_limit = s->parameters.max_bandwidth / XFER_LIMIT_RATIO;
 
         /* Notify before starting migration thread */
-        notifier_list_notify(&migration_state_notifiers, s);
+        migration_call_notifiers(s);
     }
 
     qemu_file_set_rate_limit(s->to_dst_file, rate_limit);
diff --git a/ui/spice-core.c b/ui/spice-core.c
index c3ac20a..62b7893 100644
--- a/ui/spice-core.c
+++ b/ui/spice-core.c
@@ -819,8 +819,7 @@ static void qemu_spice_init(void)
     };
     using_spice = 1;
 
-    migration_state.notify = migration_state_notifier;
-    add_migration_state_change_notifier(&migration_state);
+    migration_add_notifier(&migration_state, migration_state_notifier);
     spice_migrate.base.sif = &migrate_interface.base;
     qemu_spice.add_interface(&spice_migrate.base);
 
-- 
1.8.3.1