migration: simplify blockers

Modify migrate_add_blocker and migrate_del_blocker to take an Error **
reason.  This allows migration to own the Error object, so that if
an error occurs in migrate_add_blocker, migration code can free the Error
and clear the client handle, simplifying client code.  It also simplifies
the migrate_del_blocker call site.

In addition, this is a pre-requisite for a proposed future patch that would
add a mode argument to migration requests to support live update, and
maintain a list of blockers for each mode.  A blocker may apply to a single
mode or to multiple modes, and passing Error** will allow one Error object
to be registered for multiple modes.

No functional change.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Tested-by: Michael Galaxy <mgalaxy@akamai.com>
Reviewed-by: Michael Galaxy <mgalaxy@akamai.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <1697634216-84215-1-git-send-email-steven.sistare@oracle.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/dump/dump.c b/dump/dump.c
index d3578ddc62..d355ada62e 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -111,7 +111,7 @@ static int dump_cleanup(DumpState *s)
             qemu_mutex_unlock_iothread();
         }
     }
-    migrate_del_blocker(dump_migration_blocker);
+    migrate_del_blocker(&dump_migration_blocker);
 
     return 0;
 }
@@ -2158,7 +2158,7 @@ void qmp_dump_guest_memory(bool paging, const char *file,
      * Allows even for -only-migratable, but forbid migration during the
      * process of dump guest memory.
      */
-    if (migrate_add_blocker_internal(dump_migration_blocker, errp)) {
+    if (migrate_add_blocker_internal(&dump_migration_blocker, errp)) {
         /* Remember to release the fd before passing it over to dump state */
         close(fd);
         return;