Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> writes:
We'll need this for realizing qdev_find_child() in the next commit.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
softmmu/qdev-monitor.c | 48 +++++++++++++++++++++++++++++-------------
1 file changed, 33 insertions(+), 15 deletions(-)
diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c
index 721dec2d82..0117989009 100644
--- a/softmmu/qdev-monitor.c
+++ b/softmmu/qdev-monitor.c
@@ -819,7 +819,12 @@ void qmp_device_add(QDict *qdict, QObject **ret_data,
Error **errp)
object_unref(OBJECT(dev));
}
-static DeviceState *find_device_state(const char *id, Error **errp)
+/*
+ * Returns: 1 when found, @dev set
+ * 0 not found, @dev and @errp untouched
+ * <0 error, or id is ambiguous, @errp set
+ */
+static int find_device_state(const char *id, DeviceState **dev, Error **errp)
{
Object *obj;
@@ -835,17 +840,16 @@ static DeviceState *find_device_state(const char *id, Error **errp)
}
if (!obj) {
- error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
- "Device '%s' not found", id);
- return NULL;
+ return 0;
}
if (!object_dynamic_cast(obj, TYPE_DEVICE)) {
error_setg(errp, "%s is not a hotpluggable device", id);
- return NULL;
+ return -EINVAL;
}
- return DEVICE(obj);
+ *dev = DEVICE(obj);
+ return 1;
}
void qdev_unplug(DeviceState *dev, Error **errp)
@@ -894,16 +898,25 @@ void qdev_unplug(DeviceState *dev, Error **errp)
void qmp_device_del(const char *id, Error **errp)
{
- DeviceState *dev = find_device_state(id, errp);
- if (dev != NULL) {
- if (dev->pending_deleted_event) {
- error_setg(errp, "Device %s is already in the "
- "process of unplug", id);
- return;
+ int ret;
+ DeviceState *dev;
+
+ ret = find_device_state(id, &dev, errp);
+ if (ret <= 0) {
+ if (ret == 0) {
+ error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
+ "Device '%s' not found", id);
}
+ return;
+ }
- qdev_unplug(dev, errp);
+ if (dev->pending_deleted_event) {
+ error_setg(errp, "Device %s is already in the "
+ "process of unplug", id);
+ return;
}
+
+ qdev_unplug(dev, errp);
}
void hmp_device_add(Monitor *mon, const QDict *qdict)
@@ -925,11 +938,16 @@ void hmp_device_del(Monitor *mon, const QDict *qdict)
BlockBackend *blk_by_qdev_id(const char *id, Error **errp)
{
+ int ret;
DeviceState *dev;
BlockBackend *blk;
- dev = find_device_state(id, errp);
- if (dev == NULL) {
+ ret = find_device_state(id, &dev, errp);
+ if (ret <= 0) {
+ if (ret == 0) {
+ error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
+ "Device '%s' not found", id);
+ }
return NULL;
}
Awkward.
Before, find_device_state() either finds something (and returns it) or
doesn't (and sets @errp).
Afterward, it can fail to find in two ways, and only one of it sets
@errp. The existing callers laboriously fuse the two back together.
The next commit adds a caller that doesn't.
Failure modes that need to be handled differently are often the result
of a function doing too much. Let's have a closer look at this one
before the patch:
static DeviceState *find_device_state(const char *id, Error **errp)
{
Object *obj;
if (id[0] == '/') {
obj = object_resolve_path(id, NULL);
This interprets @id as a QOM path, and tries to resolve it.
On failure, @obj becomes NULL. On success, it points to an object of
arbitrary type.
} else {
char *root_path = object_get_canonical_path(qdev_get_peripheral());
char *path = g_strdup_printf("%s/%s", root_path, id);
g_free(root_path);
obj = object_resolve_path_type(path, TYPE_DEVICE, NULL);
g_free(path);
This interprets @id as qdev ID, maps it to a QOM path, and tries to
resolve it to a TYPE_DEVICE. Fails when the path doesn't resolve, and
when it resolves to something that isn't a TYPE_DEVICE. The latter
can't happen as long as we put only devices under /machine/peripheral/.
On failure, @obj becomes NULL. On success, it points to a TYPE_DEVICE
object.
}
if (!obj) {
error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
"Device '%s' not found", id);
return NULL;
}
if (!object_dynamic_cast(obj, TYPE_DEVICE)) {
error_setg(errp, "%s is not a hotpluggable device", id);
return NULL;
}
Unclean.
If we somehow ended up with a non-device /machine/peripheral/foo, then
find_device_state("foo", errp) would fail the first way, but
find_device_state("/machine/peripheral/foo", errp) would fail the second
way. They should fail the exact same way instead.
return DEVICE(obj);
}
Better:
static DeviceState *find_device_state(const char *id, Error **errp)
{
Object *obj;
DeviceState *dev;
if (id[0] == '/') {
obj = object_resolve_path(id, NULL);
} else {
obj = object_resolve_path_component(qdev_get_peripheral(), id);
}
if (!obj) {
error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND,
"Device '%s' not found", id);
return NULL;
}
dev = (DeviceState *)object_dynamic_cast(obj, TYPE_DEVICE);
if (!dev) {
error_setg(errp, "%s is not a hotpluggable device", id);
return NULL;
}
return dev;
}