migration: Handle migration_incoming_setup() errors consistently

Commit b673eab "multifd: Make multifd_load_setup() get an Error
parameter" changed migration_incoming_setup() to take an Error **
argument, and adjusted the callers accordingly.  It neglected to
change adjust multifd_load_setup(): it still exit()s on error.  Clean
that up.

The error now gets propagated up two call chains: via
migration_fd_process_incoming() to rdma_accept_incoming_migration(),
and via migration_ioc_process_incoming() to
migration_channel_process_incoming().  Both chain ends report the
error with error_report_err(), but otherwise ignore it.  Behavioral
change: we no longer exit() on this error.

This is consistent with how we handle other errors here, e.g. from
multifd_recv_new_channel() via migration_ioc_process_incoming() to
migration_channel_process_incoming().  Whether it's consistently right
or consistently wrong I can't tell.

Also clean up the return value from the unusual 0 on success, 1 on
error to the more common true on success, false on error.

Cc: Juan Quintela <[email protected]>
Cc: Dr. David Alan Gilbert <[email protected]>
Signed-off-by: Markus Armbruster <[email protected]>
Message-Id: <[email protected]>
Reviewed-by: Eric Blake <[email protected]>
Reviewed-by: Pankaj Gupta <[email protected]>
Acked-by: Michael S. Tsirkin <[email protected]>

Author: Markus Armbruster

migration/migration.c

@@ -611,30 +611,25 @@ static void process_incoming_migration_co(void *opaque)
 }
 
 /**
- * @migration_incoming_setup: Setup incoming migration
- *
- * Returns 0 for no error or 1 for error
- *
+ * migration_incoming_setup: Setup incoming migration
  * @f: file for main migration channel
  * @errp: where to put errors
+ *
+ * Returns: %true on success, %false on error.
  */
-static int migration_incoming_setup(QEMUFile *f, Error **errp)
+static bool migration_incoming_setup(QEMUFile *f, Error **errp)
 {
     MigrationIncomingState *mis = migration_incoming_get_current();
-    Error *local_err = NULL;
 
-    if (multifd_load_setup(&local_err) != 0) {
-        /* We haven't been able to create multifd threads
-           nothing better to do */
-        error_report_err(local_err);
-        exit(EXIT_FAILURE);
+    if (multifd_load_setup(errp) != 0) {
+        return false;
     }
 
     if (!mis->from_src_file) {
         mis->from_src_file = f;
     }
     qemu_file_set_blocking(f, false);
-    return 0;
+    return true;
 }
 
 void migration_incoming_process(void)
@@ -677,14 +672,11 @@ static bool postcopy_try_recover(QEMUFile *f)
 
 void migration_fd_process_incoming(QEMUFile *f, Error **errp)
 {
-    Error *local_err = NULL;
-
     if (postcopy_try_recover(f)) {
         return;
     }
 
-    if (migration_incoming_setup(f, &local_err)) {
-        error_propagate(errp, local_err);
+    if (!migration_incoming_setup(f, errp)) {
         return;
     }
     migration_incoming_process();
@@ -705,8 +697,7 @@ void migration_ioc_process_incoming(QIOChannel *ioc, Error **errp)
             return;
         }
 
-        if (migration_incoming_setup(f, &local_err)) {
-            error_propagate(errp, local_err);
+        if (!migration_incoming_setup(f, errp)) {
             return;
         }