Re: [Qemu-devel] [PATCH v2 7/7] qdev-monitor: Propagate errors through qdev_device_add()

["Andreas Färber" <afaerber@suse.de>]

Am 13.06.2015 um 13:18 schrieb Markus Armbruster:
> Also polish an error message while I'm touching the line anyway,
> 
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> Reviewed-by: Eric Blake <eblake@redhat.com>
> ---
>  include/monitor/qdev.h |  2 +-
>  qdev-monitor.c         | 36 +++++++++++++++---------------------
>  vl.c                   |  7 +++++--
>  3 files changed, 21 insertions(+), 24 deletions(-)
> 
> diff --git a/include/monitor/qdev.h b/include/monitor/qdev.h
> index 7190752..2ce8578 100644
> --- a/include/monitor/qdev.h
> +++ b/include/monitor/qdev.h
> @@ -11,6 +11,6 @@ void hmp_info_qdm(Monitor *mon, const QDict *qdict);
>  void hmp_info_qom_tree(Monitor *mon, const QDict *dict);
>  int do_device_add(Monitor *mon, const QDict *qdict, QObject **ret_data);
>  int qdev_device_help(QemuOpts *opts);
> -DeviceState *qdev_device_add(QemuOpts *opts);
> +DeviceState *qdev_device_add(QemuOpts *opts, Error **errp);
>  
>  #endif
> diff --git a/qdev-monitor.c b/qdev-monitor.c
> index e7e9a50..686c9df 100644
> --- a/qdev-monitor.c
> +++ b/qdev-monitor.c
> @@ -516,7 +516,7 @@ static BusState *qbus_find(const char *path, Error **errp)
>      return bus;
>  }
>  
> -DeviceState *qdev_device_add(QemuOpts *opts)
> +DeviceState *qdev_device_add(QemuOpts *opts, Error **errp)
>  {
>      DeviceClass *dc;
>      const char *driver, *path, *id;
> @@ -526,44 +526,38 @@ DeviceState *qdev_device_add(QemuOpts *opts)
>  
>      driver = qemu_opt_get(opts, "driver");
>      if (!driver) {
> -        qerror_report(QERR_MISSING_PARAMETER, "driver");
> +        error_set(errp, QERR_MISSING_PARAMETER, "driver");
>          return NULL;
>      }
>  
>      /* find driver */
> -    dc = qdev_get_device_class(&driver, &err);
> -    if (err) {
> -        qerror_report_err(err);
> -        error_free(err);
> +    dc = qdev_get_device_class(&driver, errp);
> +    if (!dc) {

Here ...

>          return NULL;
>      }
>  
>      /* find bus */
>      path = qemu_opt_get(opts, "bus");
>      if (path != NULL) {
> -        bus = qbus_find(path, &err);
> +        bus = qbus_find(path, errp);
>          if (!bus) {
> -            qerror_report_err(err);
> -            error_free(err);

... and here you've elegantly eliminated assumptions about return value
and errp relations. Before, we were accessing err without checking that
it is non-NULL - error_free() shouldn't care but qerror_report_err()
might and just out of design principle.

>              return NULL;
>          }
>          if (!object_dynamic_cast(OBJECT(bus), dc->bus_type)) {
> -            qerror_report(ERROR_CLASS_GENERIC_ERROR,
> -                          "Device '%s' can't go on a %s bus",
> -                          driver, object_get_typename(OBJECT(bus)));
> +            error_setg(errp, "Device '%s' can't go on %s bus",
> +                       driver, object_get_typename(OBJECT(bus)));
>              return NULL;
>          }
>      } else if (dc->bus_type != NULL) {
>          bus = qbus_find_recursive(sysbus_get_default(), NULL, dc->bus_type);
>          if (!bus || qbus_is_full(bus)) {
> -            qerror_report(ERROR_CLASS_GENERIC_ERROR,
> -                          "No '%s' bus found for device '%s'",
> -                          dc->bus_type, driver);
> +            error_setg(errp, "No '%s' bus found for device '%s'",
> +                       dc->bus_type, driver);
>              return NULL;
>          }
>      }
>      if (qdev_hotplug && bus && !qbus_is_hotpluggable(bus)) {
> -        qerror_report(QERR_BUS_NO_HOTPLUG, bus->name);
> +        error_set(errp, QERR_BUS_NO_HOTPLUG, bus->name);
>          return NULL;
>      }
>  
> @@ -592,7 +586,7 @@ DeviceState *qdev_device_add(QemuOpts *opts)
>  
>      /* set properties */
>      if (qemu_opt_foreach(opts, set_property, dev, &err)) {
> -        qerror_report_err(err);
> +        error_propagate(errp, err);
>          object_unparent(OBJECT(dev));
>          object_unref(OBJECT(dev));
>          return NULL;
> @@ -601,12 +595,10 @@ DeviceState *qdev_device_add(QemuOpts *opts)
>      dev->opts = opts;
>      object_property_set_bool(OBJECT(dev), true, "realized", &err);
>      if (err != NULL) {
> -        qerror_report_err(err);
> -        error_free(err);
> +        error_propagate(errp, err);
>          dev->opts = NULL;
>          object_unparent(OBJECT(dev));
>          object_unref(OBJECT(dev));
> -        qerror_report(QERR_DEVICE_INIT_FAILED, driver);
>          return NULL;
>      }
>      return dev;
> @@ -779,8 +771,10 @@ int do_device_add(Monitor *mon, const QDict *qdict, QObject **ret_data)
>          qemu_opts_del(opts);
>          return 0;
>      }
> -    dev = qdev_device_add(opts);
> +    dev = qdev_device_add(opts, &local_err);
>      if (!dev) {

Would seem safer to change this to "if (local_err) {" now that it is
dealing with local_err.

> +        qerror_report_err(local_err);
> +        error_free(local_err);
>          qemu_opts_del(opts);
>          return -1;
>      }
> diff --git a/vl.c b/vl.c
> index 9542095..f0dcb6b 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -2185,11 +2185,14 @@ static int device_help_func(void *opaque, QemuOpts *opts, Error **errp)
>  
>  static int device_init_func(void *opaque, QemuOpts *opts, Error **errp)
>  {
> +    Error *err = NULL;
>      DeviceState *dev;
>  
> -    dev = qdev_device_add(opts);
> -    if (!dev)
> +    dev = qdev_device_add(opts, &err);
> +    if (!dev) {
> +        error_report_err(err);
>          return -1;
> +    }
>      object_unref(OBJECT(dev));
>      return 0;
>  }

Anyway,

Reviewed-by: Andreas Färber <afaerber@suse.de>

Regards,
Andreas

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