xen: Use ERRP_GUARD()

If we want to check error after errp-function call, we need to
introduce local_err and then propagate it to errp. Instead, use
the ERRP_GUARD() macro, benefits are:
1. No need of explicit error_propagate call
2. No need of explicit local_err variable: use errp directly
3. ERRP_GUARD() leaves errp as is if it's not NULL or
   &error_fatal, this means that we don't break error_abort
   (we'll abort on error_set, not on error_propagate)

If we want to add some info to errp (by error_prepend() or
error_append_hint()), we must use the ERRP_GUARD() macro.
Otherwise, this info will not be added when errp == &error_fatal
(the program will exit prior to the error_append_hint() or
error_prepend() call).  No such cases are being fixed here.

This commit is generated by command

    sed -n '/^X86 Xen CPUs$/,/^$/{s/^F: //p}' MAINTAINERS | \
    xargs git ls-files | grep '\.[hc]$' | \
    xargs spatch \
        --sp-file scripts/coccinelle/errp-guard.cocci \
        --macro-file scripts/cocci-macro-file.h \
        --in-place --no-show-diff --max-width 80

Reported-by: Kevin Wolf <kwolf@redhat.com>
Reported-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20200707165037.1026246-9-armbru@redhat.com>
[ERRP_AUTO_PROPAGATE() renamed to ERRP_GUARD(), and
auto-propagated-errp.cocci to errp-guard.cocci.  Commit message
tweaked again.]

2 files changed, 50 insertions, 69 deletions

diff --git a/hw/block/dataplane/xen-block.c b/hw/block/dataplane/xen-block.c
index 5f8f15778b..71c337c7b7 100644
--- a/hw/block/dataplane/xen-block.c
+++ b/hw/block/dataplane/xen-block.c
@@ -723,8 +723,8 @@ void xen_block_dataplane_start(XenBlockDataPlane *dataplane,
                                unsigned int protocol,
                                Error **errp)
 {
+    ERRP_GUARD();
     XenDevice *xendev = dataplane->xendev;
-    Error *local_err = NULL;
     unsigned int ring_size;
     unsigned int i;
 
@@ -760,9 +760,8 @@ void xen_block_dataplane_start(XenBlockDataPlane *dataplane,
     }
 
     xen_device_set_max_grant_refs(xendev, dataplane->nr_ring_ref,
-                                  &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+                                  errp);
+    if (*errp) {
         goto stop;
     }
 
@@ -770,9 +769,8 @@ void xen_block_dataplane_start(XenBlockDataPlane *dataplane,
                                               dataplane->ring_ref,
                                               dataplane->nr_ring_ref,
                                               PROT_READ | PROT_WRITE,
-                                              &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+                                              errp);
+    if (*errp) {
         goto stop;
     }
 
@@ -805,9 +803,8 @@ void xen_block_dataplane_start(XenBlockDataPlane *dataplane,
     dataplane->event_channel =
         xen_device_bind_event_channel(xendev, event_channel,
                                       xen_block_dataplane_event, dataplane,
-                                      &local_err);
-    if (local_err) {
-        error_propagate(errp, local_err);
+                                      errp);
+    if (*errp) {
         goto stop;
     }
 
diff --git a/hw/block/xen-block.c b/hw/block/xen-block.c
index a775fba7c0..8a7a3f5452 100644
--- a/hw/block/xen-block.c
+++ b/hw/block/xen-block.c
@@ -195,6 +195,7 @@ static const BlockDevOps xen_block_dev_ops = {
 
 static void xen_block_realize(XenDevice *xendev, Error **errp)
 {
+    ERRP_GUARD();
     XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
     XenBlockDeviceClass *blockdev_class =
         XEN_BLOCK_DEVICE_GET_CLASS(xendev);
@@ -202,7 +203,6 @@ static void xen_block_realize(XenDevice *xendev, Error **errp)
     XenBlockVdev *vdev = &blockdev->props.vdev;
     BlockConf *conf = &blockdev->props.conf;
     BlockBackend *blk = conf->blk;
-    Error *local_err = NULL;
 
     if (vdev->type == XEN_BLOCK_VDEV_TYPE_INVALID) {
         error_setg(errp, "vdev property not set");
@@ -212,9 +212,8 @@ static void xen_block_realize(XenDevice *xendev, Error **errp)
     trace_xen_block_realize(type, vdev->disk, vdev->partition);
 
     if (blockdev_class->realize) {
-        blockdev_class->realize(blockdev, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        blockdev_class->realize(blockdev, errp);
+        if (*errp) {
             return;
         }
     }
@@ -280,8 +279,8 @@ static void xen_block_frontend_changed(XenDevice *xendev,
                                        enum xenbus_state frontend_state,
                                        Error **errp)
 {
+    ERRP_GUARD();
     enum xenbus_state backend_state = xen_device_backend_get_state(xendev);
-    Error *local_err = NULL;
 
     switch (frontend_state) {
     case XenbusStateInitialised:
@@ -290,15 +289,13 @@ static void xen_block_frontend_changed(XenDevice *xendev,
             break;
         }
 
-        xen_block_disconnect(xendev, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        xen_block_disconnect(xendev, errp);
+        if (*errp) {
             break;
         }
 
-        xen_block_connect(xendev, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        xen_block_connect(xendev, errp);
+        if (*errp) {
             break;
         }
 
@@ -311,9 +308,8 @@ static void xen_block_frontend_changed(XenDevice *xendev,
 
     case XenbusStateClosed:
     case XenbusStateUnknown:
-        xen_block_disconnect(xendev, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        xen_block_disconnect(xendev, errp);
+        if (*errp) {
             break;
         }
 
@@ -665,9 +661,9 @@ static void xen_block_blockdev_del(const char *node_name, Error **errp)
 static char *xen_block_blockdev_add(const char *id, QDict *qdict,
                                     Error **errp)
 {
+    ERRP_GUARD();
     const char *driver = qdict_get_try_str(qdict, "driver");
     BlockdevOptions *options = NULL;
-    Error *local_err = NULL;
     char *node_name;
     Visitor *v;
 
@@ -688,10 +684,9 @@ static char *xen_block_blockdev_add(const char *id, QDict *qdict,
         goto fail;
     }
 
-    qmp_blockdev_add(options, &local_err);
+    qmp_blockdev_add(options, errp);
 
-    if (local_err) {
-        error_propagate(errp, local_err);
+    if (*errp) {
         goto fail;
     }
 
@@ -710,14 +705,12 @@ fail:
 
 static void xen_block_drive_destroy(XenBlockDrive *drive, Error **errp)
 {
+    ERRP_GUARD();
     char *node_name = drive->node_name;
 
     if (node_name) {
-        Error *local_err = NULL;
-
-        xen_block_blockdev_del(node_name, &local_err);
-        if (local_err) {
-            error_propagate(errp, local_err);
+        xen_block_blockdev_del(node_name, errp);
+        if (*errp) {
             return;
         }
         g_free(node_name);
@@ -731,6 +724,7 @@ static XenBlockDrive *xen_block_drive_create(const char *id,
                                              const char *device_type,
                                              QDict *opts, Error **errp)
 {
+    ERRP_GUARD();
     const char *params = qdict_get_try_str(opts, "params");
     const char *mode = qdict_get_try_str(opts, "mode");
     const char *direct_io_safe = qdict_get_try_str(opts, "direct-io-safe");
@@ -738,7 +732,6 @@ static XenBlockDrive *xen_block_drive_create(const char *id,
     char *driver = NULL;
     char *filename = NULL;
     XenBlockDrive *drive = NULL;
-    Error *local_err = NULL;
     QDict *file_layer;
     QDict *driver_layer;
 
@@ -817,13 +810,12 @@ static XenBlockDrive *xen_block_drive_create(const char *id,
 
     g_assert(!drive->node_name);
     drive->node_name = xen_block_blockdev_add(drive->id, driver_layer,
-                                              &local_err);
+                                              errp);
 
     qobject_unref(driver_layer);
 
 done:
-    if (local_err) {
-        error_propagate(errp, local_err);
+    if (*errp) {
         xen_block_drive_destroy(drive, NULL);
         return NULL;
     }
@@ -848,8 +840,8 @@ static void xen_block_iothread_destroy(XenBlockIOThread *iothread,
 static XenBlockIOThread *xen_block_iothread_create(const char *id,
                                                    Error **errp)
 {
+    ERRP_GUARD();
     XenBlockIOThread *iothread = g_new(XenBlockIOThread, 1);
-    Error *local_err = NULL;
     QDict *opts;
     QObject *ret_data = NULL;
 
@@ -858,13 +850,11 @@ static XenBlockIOThread *xen_block_iothread_create(const char *id,
     opts = qdict_new();
     qdict_put_str(opts, "qom-type", TYPE_IOTHREAD);
     qdict_put_str(opts, "id", id);
-    qmp_object_add(opts, &ret_data, &local_err);
+    qmp_object_add(opts, &ret_data, errp);
     qobject_unref(opts);
     qobject_unref(ret_data);
 
-    if (local_err) {
-        error_propagate(errp, local_err);
-
+    if (*errp) {
         g_free(iothread->id);
         g_free(iothread);
         return NULL;
@@ -876,6 +866,7 @@ static XenBlockIOThread *xen_block_iothread_create(const char *id,
 static void xen_block_device_create(XenBackendInstance *backend,
                                     QDict *opts, Error **errp)
 {
+    ERRP_GUARD();
     XenBus *xenbus = xen_backend_get_bus(backend);
     const char *name = xen_backend_get_name(backend);
     unsigned long number;
@@ -883,7 +874,6 @@ static void xen_block_device_create(XenBackendInstance *backend,
     XenBlockDrive *drive = NULL;
     XenBlockIOThread *iothread = NULL;
     XenDevice *xendev = NULL;
-    Error *local_err = NULL;
     const char *type;
     XenBlockDevice *blockdev;
 
@@ -915,16 +905,15 @@ static void xen_block_device_create(XenBackendInstance *backend,
         goto fail;
     }
 
-    drive = xen_block_drive_create(vdev, device_type, opts, &local_err);
+    drive = xen_block_drive_create(vdev, device_type, opts, errp);
     if (!drive) {
-        error_propagate_prepend(errp, local_err, "failed to create drive: ");
+        error_prepend(errp, "failed to create drive: ");
         goto fail;
     }
 
-    iothread = xen_block_iothread_create(vdev, &local_err);
-    if (local_err) {
-        error_propagate_prepend(errp, local_err,
-                                "failed to create iothread: ");
+    iothread = xen_block_iothread_create(vdev, errp);
+    if (*errp) {
+        error_prepend(errp, "failed to create iothread: ");
         goto fail;
     }
 
@@ -932,32 +921,29 @@ static void xen_block_device_create(XenBackendInstance *backend,
     blockdev = XEN_BLOCK_DEVICE(xendev);
 
     if (!object_property_set_str(OBJECT(xendev), "vdev", vdev,
-                                 &local_err)) {
-        error_propagate_prepend(errp, local_err, "failed to set 'vdev': ");
+                                 errp)) {
+        error_prepend(errp, "failed to set 'vdev': ");
         goto fail;
     }
 
     if (!object_property_set_str(OBJECT(xendev), "drive",
                                  xen_block_drive_get_node_name(drive),
-                                 &local_err)) {
-        error_propagate_prepend(errp, local_err, "failed to set 'drive': ");
+                                 errp)) {
+        error_prepend(errp, "failed to set 'drive': ");
         goto fail;
     }
 
     if (!object_property_set_str(OBJECT(xendev), "iothread", iothread->id,
-                                 &local_err)) {
-        error_propagate_prepend(errp, local_err,
-                                "failed to set 'iothread': ");
+                                 errp)) {
+        error_prepend(errp, "failed to set 'iothread': ");
         goto fail;
     }
 
     blockdev->iothread = iothread;
     blockdev->drive = drive;
 
-    if (!qdev_realize_and_unref(DEVICE(xendev), BUS(xenbus), &local_err)) {
-        error_propagate_prepend(errp, local_err,
-                                "realization of device %s failed: ",
-                                type);
+    if (!qdev_realize_and_unref(DEVICE(xendev), BUS(xenbus), errp)) {
+        error_prepend(errp, "realization of device %s failed: ", type);
         goto fail;
     }
 
@@ -981,31 +967,29 @@ fail:
 static void xen_block_device_destroy(XenBackendInstance *backend,
                                      Error **errp)
 {
+    ERRP_GUARD();
     XenDevice *xendev = xen_backend_get_device(backend);
     XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
     XenBlockVdev *vdev = &blockdev->props.vdev;
     XenBlockDrive *drive = blockdev->drive;
     XenBlockIOThread *iothread = blockdev->iothread;
-    Error *local_err = NULL;
 
     trace_xen_block_device_destroy(vdev->number);
 
     object_unparent(OBJECT(xendev));
 
     if (iothread) {
-        xen_block_iothread_destroy(iothread, &local_err);
-        if (local_err) {
-            error_propagate_prepend(errp, local_err,
-                                    "failed to destroy iothread: ");
+        xen_block_iothread_destroy(iothread, errp);
+        if (*errp) {
+            error_prepend(errp, "failed to destroy iothread: ");
             return;
         }
     }
 
     if (drive) {
-        xen_block_drive_destroy(drive, &local_err);
-        if (local_err) {
-            error_propagate_prepend(errp, local_err,
-                                    "failed to destroy drive: ");
+        xen_block_drive_destroy(drive, errp);
+        if (*errp) {
+            error_prepend(errp, "failed to destroy drive: ");
             return;
         }
     }