Re: [PATCH 02/11] xen: Fix and improve handling of device_add usb-host errors

[Markus Armbruster <armbru@xxxxxxxxxx>]

Paul Durrant <xadimgnik@xxxxxxxxx> writes:

>> -----Original Message-----
>> From: Markus Armbruster <armbru@xxxxxxxxxx>
>> Sent: 24 April 2020 20:20
>> To: qemu-devel@xxxxxxxxxx
>> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>; Anthony Perard 
>> <anthony.perard@xxxxxxxxxx>; Paul
>> Durrant <paul@xxxxxxx>; Gerd Hoffmann <kraxel@xxxxxxxxxx>; 
>> xen-devel@xxxxxxxxxxxxxxxxxxxx
>> Subject: [PATCH 02/11] xen: Fix and improve handling of device_add usb-host 
>> errors
>> 
>> usbback_portid_add() leaks the error when qdev_device_add() fails.
>> Fix that.  While there, use the error to improve the error message.
>> 
>> The qemu_opts_from_qdict() similarly leaks on failure.  But any
>> failure there is a programming error.  Pass &error_abort.
>> 
>> Fixes: 816ac92ef769f9ffc534e49a1bb6177bddce7aa2
>> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
>> Cc: Anthony Perard <anthony.perard@xxxxxxxxxx>
>> Cc: Paul Durrant <paul@xxxxxxx>
>> Cc: Gerd Hoffmann <kraxel@xxxxxxxxxx>
>> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
>> Signed-off-by: Markus Armbruster <armbru@xxxxxxxxxx>
>> ---
>>  hw/usb/xen-usb.c | 18 ++++++++----------
>>  1 file changed, 8 insertions(+), 10 deletions(-)
>> 
>> diff --git a/hw/usb/xen-usb.c b/hw/usb/xen-usb.c
>> index 961190d0f7..42643c3390 100644
>> --- a/hw/usb/xen-usb.c
>> +++ b/hw/usb/xen-usb.c
>> @@ -30,6 +30,7 @@
>>  #include "hw/usb.h"
>>  #include "hw/xen/xen-legacy-backend.h"
>>  #include "monitor/qdev.h"
>> +#include "qapi/error.h"
>>  #include "qapi/qmp/qdict.h"
>>  #include "qapi/qmp/qstring.h"
>> 
>> @@ -755,13 +756,15 @@ static void usbback_portid_add(struct usbback_info 
>> *usbif, unsigned port,
>>      qdict_put_int(qdict, "port", port);
>>      qdict_put_int(qdict, "hostbus", atoi(busid));
>>      qdict_put_str(qdict, "hostport", portname);
>> -    opts = qemu_opts_from_qdict(qemu_find_opts("device"), qdict, 
>> &local_err);
>> -    if (local_err) {
>> -        goto err;
>> -    }
>> +    opts = qemu_opts_from_qdict(qemu_find_opts("device"), qdict,
>> +                                &error_abort);
>>      usbif->ports[port - 1].dev = USB_DEVICE(qdev_device_add(opts, 
>> &local_err));
>>      if (!usbif->ports[port - 1].dev) {
>> -        goto err;
>> +        qobject_unref(qdict);
>> +        xen_pv_printf(&usbif->xendev, 0,
>> +                      "device %s could not be opened: %s\n",
>> +                      busid, error_get_pretty(local_err));
>> +        error_free(local_err);
>
> Previously the goto caused the function to bail out. Should there not be a 
> 'return' here?

Owww, of course.  Thanks!

>
>>      }
>>      qobject_unref(qdict);
>>      speed = usbif->ports[port - 1].dev->speed;
>> @@ -793,11 +796,6 @@ static void usbback_portid_add(struct usbback_info 
>> *usbif, unsigned port,
>>      usbback_hotplug_enq(usbif, port);
>> 
>>      TR_BUS(&usbif->xendev, "port %d attached\n", port);
>> -    return;
>> -
>> -err:
>> -    qobject_unref(qdict);
>> -    xen_pv_printf(&usbif->xendev, 0, "device %s could not be opened\n", 
>> busid);
>>  }
>> 
>>  static void usbback_process_port(struct usbback_info *usbif, unsigned port)
>> --
>> 2.21.1