migration: multi-mode notifier

Allow a notifier to be added for multiple migration modes.
To allow a notifier to appear on multiple per-node lists, use
a generic list type.  We can no longer use NotifierWithReturnList,
because it shoe horns the notifier onto a single list.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/1759332851-370353-2-git-send-email-steven.sistare@oracle.com
Signed-off-by: Peter Xu <peterx@redhat.com>

include/migration/misc.h

@@ -95,7 +95,19 @@ void migration_add_notifier(NotifierWithReturn *notify,
 void migration_add_notifier_mode(NotifierWithReturn *notify,
                                  MigrationNotifyFunc func, MigMode mode);
 
+/*
+ * Same as migration_add_notifier, but applies to all @mode in the argument
+ * list.  The list is terminated by -1 or MIG_MODE_ALL.  For the latter,
+ * the notifier is added for all modes.
+ */
+void migration_add_notifier_modes(NotifierWithReturn *notify,
+                                  MigrationNotifyFunc func, MigMode mode, ...);
+
+/*
+ * Remove a notifier from all modes.
+ */
 void migration_remove_notifier(NotifierWithReturn *notify);
+
 void migration_file_set_error(int ret, Error *err);
 
 /* True if incoming migration entered POSTCOPY_INCOMING_DISCARD */

migration/migration.c

@@ -74,11 +74,7 @@
 
 #define INMIGRATE_DEFAULT_EXIT_ON_ERROR true
 
-static NotifierWithReturnList migration_state_notifiers[] = {
+static GSList *migration_state_notifiers[MIG_MODE__MAX];
-    NOTIFIER_ELEM_INIT(migration_state_notifiers, MIG_MODE_NORMAL),
-    NOTIFIER_ELEM_INIT(migration_state_notifiers, MIG_MODE_CPR_REBOOT),
-    NOTIFIER_ELEM_INIT(migration_state_notifiers, MIG_MODE_CPR_TRANSFER),
-};
 
 /* Messages sent on the return path from destination to source */
 enum mig_rp_message_type {
@@ -1675,23 +1671,51 @@ void migration_cancel(void)
     }
 }
 
+static int get_modes(MigMode mode, va_list ap);
+
+static void add_notifiers(NotifierWithReturn *notify, int modes)
+{
+    for (MigMode mode = 0; mode < MIG_MODE__MAX; mode++) {
+        if (modes & BIT(mode)) {
+            migration_state_notifiers[mode] =
+                g_slist_prepend(migration_state_notifiers[mode], notify);
+        }
+    }
+}
+
+void migration_add_notifier_modes(NotifierWithReturn *notify,
+                                  MigrationNotifyFunc func, MigMode mode, ...)
+{
+    int modes;
+    va_list ap;
+
+    va_start(ap, mode);
+    modes = get_modes(mode, ap);
+    va_end(ap);
+
+    notify->notify = (NotifierWithReturnFunc)func;
+    add_notifiers(notify, modes);
+}
+
 void migration_add_notifier_mode(NotifierWithReturn *notify,
                                  MigrationNotifyFunc func, MigMode mode)
 {
-    notify->notify = (NotifierWithReturnFunc)func;
+    migration_add_notifier_modes(notify, func, mode, -1);
-    notifier_with_return_list_add(&migration_state_notifiers[mode], notify);
 }
 
 void migration_add_notifier(NotifierWithReturn *notify,
                             MigrationNotifyFunc func)
 {
-    migration_add_notifier_mode(notify, func, MIG_MODE_NORMAL);
+    migration_add_notifier_modes(notify, func, MIG_MODE_NORMAL, -1);
 }
 
 void migration_remove_notifier(NotifierWithReturn *notify)
 {
     if (notify->notify) {
-        notifier_with_return_remove(notify);
+        for (MigMode mode = 0; mode < MIG_MODE__MAX; mode++) {
+            migration_blockers[mode] =
+                g_slist_remove(migration_state_notifiers[mode], notify);
+        }
         notify->notify = NULL;
     }
 }
@@ -1701,13 +1725,23 @@ int migration_call_notifiers(MigrationState *s, MigrationEventType type,
 {
     MigMode mode = s->parameters.mode;
     MigrationEvent e;
+    NotifierWithReturn *notifier;
+    GSList *elem, *next;
     int ret;
 
     e.type = type;
-    ret = notifier_with_return_list_notify(&migration_state_notifiers[mode],
+
-                                           &e, errp);
+    for (elem = migration_state_notifiers[mode]; elem; elem = next) {
-    assert(!ret || type == MIG_EVENT_PRECOPY_SETUP);
+        next = elem->next;
-    return ret;
+        notifier = (NotifierWithReturn *)elem->data;
+        ret = notifier->notify(notifier, &e, errp);
+        if (ret) {
+            assert(type == MIG_EVENT_PRECOPY_SETUP);
+            return ret;
+        }
+    }
+
+    return 0;
 }
 
 bool migration_has_failed(MigrationState *s)