migration: Introduce migrate_has_error()

Introduce a helper to detect whether MigrationState.error is set for
whatever reason.

This is preparation work for any thread (e.g. source return path thread) to
setup errors in an unified way to MigrationState, rather than relying on
its own way to set errors (mark_source_rp_bad()).

Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20231004220240.167175-3-peterx@redhat.com>

2 files changed, 8 insertions, 0 deletions

diff --git a/migration/migration.c b/migration/migration.c
index 57f9e9e..409eb3e 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1234,6 +1234,13 @@ void migrate_set_error(MigrationState *s, const Error *error)
     }
 }
 
+bool migrate_has_error(MigrationState *s)
+{
+    /* The lock is not helpful here, but still follow the rule */
+    QEMU_LOCK_GUARD(&s->error_mutex);
+    return qatomic_read(&s->error);
+}
+
 static void migrate_error_free(MigrationState *s)
 {
     QEMU_LOCK_GUARD(&s->error_mutex);
diff --git a/migration/migration.h b/migration/migration.h
index 972597f..4106a1d 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -476,6 +476,7 @@ bool  migration_has_all_channels(void);
 uint64_t migrate_max_downtime(void);
 
 void migrate_set_error(MigrationState *s, const Error *error);
+bool migrate_has_error(MigrationState *s);
 
 void migrate_fd_connect(MigrationState *s, Error *error_in);