5:33 a.m.
Hi Kevin,
I proposed a very similar patch in our rfc series because we needed some
of the cleaning you do here.
https://lists.gnu.org/archive/html/qemu-devel/2021-09/msg05679.html
I've added a bit of doc for the function, feel free to take it if you want.
On 9/24/21 16:09, Vladimir Sementsov-Ogievskiy wrote:
24.09.2021 12:04, Kevin Wolf wrote:
> object_property_add_child() fails (with &error_abort) if an object with
> the same name already exists. As long as QemuOpts is in use for -device
> and device_add, it catches duplicate IDs before qdev_set_id() is even
> called. However, for enabling non-QemuOpts code paths, we need to make
> sure that the condition doesn't cause a crash, but fails gracefully.
>
> Signed-off-by: Kevin Wolf <kwolf(a)redhat.com>
> ---
> include/monitor/qdev.h | 2 +-
> hw/xen/xen-legacy-backend.c | 3 ++-
> softmmu/qdev-monitor.c | 16 ++++++++++------
> 3 files changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/include/monitor/qdev.h b/include/monitor/qdev.h
> index 389287eb44..7961308c75 100644
> --- a/include/monitor/qdev.h
> +++ b/include/monitor/qdev.h
> @@ -9,6 +9,6 @@ void qmp_device_add(QDict *qdict, QObject **ret_data,
> Error **errp);
> int qdev_device_help(QemuOpts *opts);
> DeviceState *qdev_device_add(QemuOpts *opts, Error **errp);
> -void qdev_set_id(DeviceState *dev, char *id);
> +void qdev_set_id(DeviceState *dev, char *id, Error **errp);
> #endif
> diff --git a/hw/xen/xen-legacy-backend.c b/hw/xen/xen-legacy-backend.c
> index dd8ae1452d..17aca85ddc 100644
> --- a/hw/xen/xen-legacy-backend.c
> +++ b/hw/xen/xen-legacy-backend.c
> @@ -276,7 +276,8 @@ static struct XenLegacyDevice
> *xen_be_get_xendev(const char *type, int dom,
> xendev = g_malloc0(ops->size);
> object_initialize(&xendev->qdev, ops->size, TYPE_XENBACKEND);
> OBJECT(xendev)->free = g_free;
> - qdev_set_id(DEVICE(xendev), g_strdup_printf("xen-%s-%d", type,
> dev));
> + qdev_set_id(DEVICE(xendev), g_strdup_printf("xen-%s-%d", type, dev),
> + &error_abort);
> qdev_realize(DEVICE(xendev), xen_sysbus, &error_fatal);
> object_unref(OBJECT(xendev));
> diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c
> index 1207e57a46..c2af906df0 100644
> --- a/softmmu/qdev-monitor.c
> +++ b/softmmu/qdev-monitor.c
> @@ -593,26 +593,27 @@ static BusState *qbus_find(const char *path,
> Error **errp)
> }
> /* Takes ownership of @id, will be freed when deleting the device */
> -void qdev_set_id(DeviceState *dev, char *id)
> +void qdev_set_id(DeviceState *dev, char *id, Error **errp)
According to recommendations in error.h, worth adding also return value
(for example true=success false=failure), so [..]
> {
> if (id) {
> dev->id = id;
> }
Unrelated but.. What's the strange logic?
Is it intended that with passed id=NULL we don't update dev->id variable
but try to do following logic with old dev->id?
dev->id is expected to be NULL. The object is created just before
calling this function so it is always the case. We could probably assert
this.
> if (dev->id) {
> - object_property_add_child(qdev_get_peripheral(), dev->id,
> - OBJECT(dev));
> + object_property_try_add_child(qdev_get_peripheral(), dev->id,
> + OBJECT(dev), errp);
> } else {
> static int anon_count;
> gchar *name = g_strdup_printf("device[%d]", anon_count++);
> - object_property_add_child(qdev_get_peripheral_anon(), name,
> - OBJECT(dev));
> + object_property_try_add_child(qdev_get_peripheral_anon(), name,
> + OBJECT(dev), errp);
> g_free(name);
> }
> }
> DeviceState *qdev_device_add(QemuOpts *opts, Error **errp)
> {
> + ERRP_GUARD();
> DeviceClass *dc;
> const char *driver, *path;
> DeviceState *dev = NULL;
> @@ -691,7 +692,10 @@ DeviceState *qdev_device_add(QemuOpts *opts,
> Error **errp)
> }
> }
> - qdev_set_id(dev, g_strdup(qemu_opts_id(opts)));
> + qdev_set_id(dev, g_strdup(qemu_opts_id(opts)), errp);
> + if (*errp) {
> + goto err_del_dev;
> + }
[..] here we'll have
if (!qdev_set_id(...)) {
goto err_del_dev;
}
and no need for ERRP_GUARD.
> /* set properties */
> if (qemu_opt_foreach(opts, set_property, dev, errp)) {
>