migration: Improve migration thread error handling

We now report errors also when we finish migration, not only on info
migrate.  We plan to use this error from several places, and we want
the first error to happen to win, so we add an mutex to order it.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

diff --git a/migration/migration.c b/migration/migration.c
index a058f8b46dfbd37fea0727c4ee79e9e587ecfa40..62761d570519de07d8f7a709feb37c6c8df0c620 100644 (file)
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1084,19 +1084,30 @@ static void migrate_fd_cleanup(void *opaque)
                           MIGRATION_STATUS_CANCELLED);
     }
 
+    if (s->error) {
+        /* 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);
     block_cleanup_parameters(s);
 }
 
+void migrate_set_error(MigrationState *s, const Error *error)
+{
+    qemu_mutex_lock(&s->error_mutex);
+    if (!s->error) {
+        s->error = error_copy(error);
+    }
+    qemu_mutex_unlock(&s->error_mutex);
+}
+
 void migrate_fd_error(MigrationState *s, const Error *error)
 {
     trace_migrate_fd_error(error_get_pretty(error));
     assert(s->to_dst_file == NULL);
     migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
                       MIGRATION_STATUS_FAILED);
-    if (!s->error) {
-        s->error = error_copy(error);
-    }
+    migrate_set_error(s, error);
     notifier_list_notify(&migration_state_notifiers, s);
     block_cleanup_parameters(s);
 }
@@ -2427,6 +2438,7 @@ static void migration_instance_finalize(Object *obj)
     MigrationState *ms = MIGRATION_OBJ(obj);
     MigrationParameters *params = &ms->parameters;
 
+    qemu_mutex_destroy(&ms->error_mutex);
     g_free(params->tls_hostname);
     g_free(params->tls_creds);
     qemu_sem_destroy(&ms->pause_sem);
@@ -2441,6 +2453,7 @@ static void migration_instance_init(Object *obj)
     ms->xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE;
     ms->mbps = -1;
     qemu_sem_init(&ms->pause_sem, 0);
+    qemu_mutex_init(&ms->error_mutex);
 
     params->tls_hostname = g_strdup("");
     params->tls_creds = g_strdup("");

diff --git a/migration/migration.h b/migration/migration.h
index cd988a99b99d06c04b5b8e881b638a6a3343681e..8ccdd7a5771a9de3aac0d8d54f3acbce80c7bce2 100644 (file)
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -132,8 +132,12 @@ struct MigrationState
     int64_t colo_checkpoint_time;
     QEMUTimer *colo_delay_timer;
 
-    /* The last error that occurred */
+    /* The first error that has occurred.
+       We used the mutex to be able to return the 1st error message */
     Error *error;
+    /* mutex to protect errp */
+    QemuMutex error_mutex;
+
     /* Do we have to clean up -b/-i from old migrate parameters */
     /* This feature is deprecated and will be removed */
     bool must_remove_block_options;
@@ -162,6 +166,7 @@ bool  migration_has_all_channels(void);
 
 uint64_t migrate_max_downtime(void);
 
+void migrate_set_error(MigrationState *s, const Error *error);
 void migrate_fd_error(MigrationState *s, const Error *error);
 
 void migrate_fd_connect(MigrationState *s);

diff --git a/migration/tls.c b/migration/tls.c
index 596e8790bdf8d129426865c83a322f1cdd6946c3..026a0086677541333f2976ea60936990e61f447c 100644 (file)
--- a/migration/tls.c
+++ b/migration/tls.c
@@ -119,7 +119,6 @@ static void migration_tls_outgoing_handshake(QIOTask *task,
     if (qio_task_propagate_error(task, &err)) {
         trace_migration_tls_outgoing_handshake_error(error_get_pretty(err));
         migrate_fd_error(s, err);
-        error_free(err);
     } else {
         trace_migration_tls_outgoing_handshake_complete();
         migration_channel_connect(s, ioc, NULL);