[PATCH v9 03/11] migration: stop returning errno from load_snapshot()

From: "Daniel P. Berrangé" <berrange@redhat.com>
To: qemu-devel@nongnu.org
Cc: "Kevin Wolf" <kwolf@redhat.com>,
	"Daniel P. Berrangé" <berrange@redhat.com>,
	qemu-block@nongnu.org, "Juan Quintela" <quintela@redhat.com>,
	"John Snow" <jsnow@redhat.com>,
	"Philippe Mathieu-Daudé" <philmd@redhat.com>,
	"Markus Armbruster" <armbru@redhat.com>,
	"Max Reitz" <mreitz@redhat.com>,
	"Pavel Dovgalyuk" <pavel.dovgaluk@ispras.ru>,
	"Pavel Dovgalyuk" <pavel.dovgalyuk@ispras.ru>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>
Subject: [PATCH v9 03/11] migration: stop returning errno from load_snapshot()
Date: Wed, 20 Jan 2021 10:44:03 +0000	[thread overview]
Message-ID: <20210120104411.3084801-4-berrange@redhat.com> (raw)
In-Reply-To: <20210120104411.3084801-1-berrange@redhat.com>

None of the callers care about the errno value since there is a full
Error object populated. This gives consistency with save_snapshot()
which already just returns a boolean value.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
[PMD: Return false/true instead of -1/0, document function]
Acked-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 include/migration/snapshot.h | 10 +++++++++-
 migration/savevm.c           | 19 +++++++++----------
 monitor/hmp-cmds.c           |  2 +-
 replay/replay-snapshot.c     |  2 +-
 softmmu/vl.c                 |  2 +-
 5 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/include/migration/snapshot.h b/include/migration/snapshot.h
index 0eaf1ba0b1..d7d210820c 100644
--- a/include/migration/snapshot.h
+++ b/include/migration/snapshot.h
@@ -23,6 +23,14 @@
  * On failure, store an error through @errp and return %false.
  */
 bool save_snapshot(const char *name, Error **errp);
-int load_snapshot(const char *name, Error **errp);
+
+/**
+ * load_snapshot: Load an internal snapshot.
+ * @name: name of internal snapshot
+ * @errp: pointer to error object
+ * On success, return %true.
+ * On failure, store an error through @errp and return %false.
+ */
+bool load_snapshot(const char *name, Error **errp);
 
 #endif
diff --git a/migration/savevm.c b/migration/savevm.c
index ef7963f6c9..e6972b56b3 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2930,7 +2930,7 @@ void qmp_xen_load_devices_state(const char *filename, Error **errp)
     migration_incoming_state_destroy();
 }
 
-int load_snapshot(const char *name, Error **errp)
+bool load_snapshot(const char *name, Error **errp)
 {
     BlockDriverState *bs_vm_state;
     QEMUSnapshotInfo sn;
@@ -2940,16 +2940,16 @@ int load_snapshot(const char *name, Error **errp)
     MigrationIncomingState *mis = migration_incoming_get_current();
 
     if (!bdrv_all_can_snapshot(errp)) {
-        return -ENOTSUP;
+        return false;
     }
     ret = bdrv_all_find_snapshot(name, errp);
     if (ret < 0) {
-        return ret;
+        return false;
     }
 
     bs_vm_state = bdrv_all_find_vmstate_bs(errp);
     if (!bs_vm_state) {
-        return -ENOTSUP;
+        return false;
     }
     aio_context = bdrv_get_aio_context(bs_vm_state);
 
@@ -2958,11 +2958,11 @@ int load_snapshot(const char *name, Error **errp)
     ret = bdrv_snapshot_find(bs_vm_state, &sn, name);
     aio_context_release(aio_context);
     if (ret < 0) {
-        return ret;
+        return false;
     } else if (sn.vm_state_size == 0) {
         error_setg(errp, "This is a disk-only snapshot. Revert to it "
                    " offline using qemu-img");
-        return -EINVAL;
+        return false;
     }
 
     /*
@@ -2983,7 +2983,6 @@ int load_snapshot(const char *name, Error **errp)
     f = qemu_fopen_bdrv(bs_vm_state, 0);
     if (!f) {
         error_setg(errp, "Could not open VM state file");
-        ret = -EINVAL;
         goto err_drain;
     }
 
@@ -3003,14 +3002,14 @@ int load_snapshot(const char *name, Error **errp)
 
     if (ret < 0) {
         error_setg(errp, "Error %d while loading VM state", ret);
-        return ret;
+        return false;
     }
 
-    return 0;
+    return true;
 
 err_drain:
     bdrv_drain_all_end();
-    return ret;
+    return false;
 }
 
 void vmstate_register_ram(MemoryRegion *mr, DeviceState *dev)
diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
index 1c4fd5cd61..8c68c05dec 100644
--- a/monitor/hmp-cmds.c
+++ b/monitor/hmp-cmds.c
@@ -1130,7 +1130,7 @@ void hmp_loadvm(Monitor *mon, const QDict *qdict)
 
     vm_stop(RUN_STATE_RESTORE_VM);
 
-    if (load_snapshot(name, &err) == 0 && saved_vm_running) {
+    if (!load_snapshot(name, &err) && saved_vm_running) {
         vm_start();
     }
     hmp_handle_error(mon, err);
diff --git a/replay/replay-snapshot.c b/replay/replay-snapshot.c
index 4f2560d156..b289365937 100644
--- a/replay/replay-snapshot.c
+++ b/replay/replay-snapshot.c
@@ -83,7 +83,7 @@ void replay_vmstate_init(void)
                 exit(1);
             }
         } else if (replay_mode == REPLAY_MODE_PLAY) {
-            if (load_snapshot(replay_snapshot, &err) != 0) {
+            if (!load_snapshot(replay_snapshot, &err)) {
                 error_report_err(err);
                 error_report("Could not load snapshot for icount replay");
                 exit(1);
diff --git a/softmmu/vl.c b/softmmu/vl.c
index 7ddf405d76..6bd7bd07c7 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -2529,7 +2529,7 @@ void qmp_x_exit_preconfig(Error **errp)
 
     if (loadvm) {
         Error *local_err = NULL;
-        if (load_snapshot(loadvm, &local_err) < 0) {
+        if (!load_snapshot(loadvm, &local_err)) {
             error_report_err(local_err);
             autostart = 0;
             exit(1);
-- 
2.29.2


