Re: [Qemu-devel] [PATCH 2/6] qdev: unref qdev when device_add fails

[Andreas Färber]

Am 10.09.2013 18:49, schrieb Paolo Bonzini:
> Il 10/09/2013 18:21, Stefan Hajnoczi ha scritto:
>> qdev_device_add() leaks the created qdev upon failure.  I suspect this
>> problem crept in because qdev_free() unparents the qdev but does not
>> drop a reference - confusing name.
> 
> Right, the name a leftover from pre-refcounting days.
> 
> BTW, not dropping a reference is the right thing to do because the
> reference is dropped much earlier, typically as soon as qdev_device_add
> returns. The QOM object tree then will still provide means to access
> devices, until they are unparented.
> 
> In this case, however, qdev_device_add's caller does not have a
> reference to free; doing that is the responsibility of qdev_device_add,
> since it returns NULL.
> 
>> Also drop trailing whitespace after curly bracket.
>>
>> Signed-off-by: Stefan Hajnoczi <address@hidden>
>> ---
>>  qdev-monitor.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/qdev-monitor.c b/qdev-monitor.c
>> index 410cdcb..5657cdc 100644
>> --- a/qdev-monitor.c
>> +++ b/qdev-monitor.c
>> @@ -512,6 +512,7 @@ DeviceState *qdev_device_add(QemuOpts *opts)
>>      }
>>      if (qemu_opt_foreach(opts, set_property, qdev, 1) != 0) {
>>          qdev_free(qdev);
>> +        object_unref(OBJECT(qdev));
>>          return NULL;
>>      }
>>      if (qdev->id) {

Given that qdev_free() doesn't do what one might expect, I would suggest
to s/qdev_free/object_unparent/g above.

>> @@ -523,8 +524,9 @@ DeviceState *qdev_device_add(QemuOpts *opts)
>>          object_property_add_child(qdev_get_peripheral_anon(), name,
>>                                    OBJECT(qdev), NULL);
>>          g_free(name);
>> -    }        
>> +    }
>>      if (qdev_init(qdev) < 0) {
>> +        object_unref(OBJECT(qdev));
>>          qerror_report(QERR_DEVICE_INIT_FAILED, driver);
>>          return NULL;
>>      }
>>
> 
> Reviewed-by: Paolo Bonzini <address@hidden>

I would like to take this through qom-next tree since I have pending
variable cleanups there ("qdev" being touched here). Not sure how to
handle that wrt block changes in this series?

Andreas

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