qemu: Preserve original error during migration

In some cases (spotted with broken connection during tunneled migration)
we were overwriting the original error with worse or even misleading
errors generated when we were cleaning up after failed migration.

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index fc8380546b85b355d9c5c3b790454ae470b19b7d..1bee66acfdac02f160d8265c254ca9026e4867a2 100644 (file)
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -1733,6 +1733,7 @@ qemuMigrationRun(struct qemud_driver *driver,
     qemuMigrationIOThreadPtr iothread = NULL;
     int fd = -1;
     unsigned long migrate_speed = resource ? resource : priv->migMaxBandwidth;
+    virErrorPtr orig_err = NULL;
 
     VIR_DEBUG("driver=%p, vm=%p, cookiein=%s, cookieinlen=%d, "
               "cookieout=%p, cookieoutlen=%p, flags=%lx, resource=%lu, "
@@ -1874,6 +1875,9 @@ qemuMigrationRun(struct qemud_driver *driver,
     ret = 0;
 
 cleanup:
+    if (ret < 0 && !orig_err)
+        orig_err = virSaveLastError();
+
     if (spec->fwdType != MIGRATION_FWD_DIRECT) {
         /* Close now to ensure the IO thread quits & is joinable */
         VIR_FORCE_CLOSE(fd);
@@ -1888,9 +1892,16 @@ cleanup:
 
     qemuMigrationCookieFree(mig);
 
+    if (orig_err) {
+        virSetError(orig_err);
+        virFreeError(orig_err);
+    }
+
     return ret;
 
 cancel:
+    orig_err = virSaveLastError();
+
     if (virDomainObjIsActive(vm)) {
         if (qemuDomainObjEnterMonitorAsync(driver, vm,
                                            QEMU_ASYNC_JOB_MIGRATION_OUT) == 0) {
@@ -2495,6 +2506,7 @@ qemuMigrationPerformJob(struct qemud_driver *driver,
     virDomainEventPtr event = NULL;
     int ret = -1;
     int resume = 0;
+    virErrorPtr orig_err = NULL;
 
     if (qemuMigrationJobStart(driver, vm, QEMU_ASYNC_JOB_MIGRATION_OUT) < 0)
         goto cleanup;
@@ -2540,6 +2552,9 @@ qemuMigrationPerformJob(struct qemud_driver *driver,
     resume = 0;
 
 endjob:
+    if (ret < 0)
+        orig_err = virSaveLastError();
+
     if (resume && virDomainObjGetState(vm, NULL) == VIR_DOMAIN_PAUSED) {
         /* we got here through some sort of failure; start the domain again */
         if (qemuProcessStartCPUs(driver, vm, conn,
@@ -2569,6 +2584,11 @@ endjob:
         vm = NULL;
     }
 
+    if (orig_err) {
+        virSetError(orig_err);
+        virFreeError(orig_err);
+    }
+
 cleanup:
     if (vm)
         virDomainObjUnlock(vm);