Re: [PATCH 1/1] softmmu: fix device deletion events with -device JSON syntax

[Thomas Huth <thuth@redhat.com>]

On 05/01/2022 16.18, Daniel P. Berrangé wrote:
> On Wed, Jan 05, 2022 at 04:00:54PM +0100, Laurent Vivier wrote:
>> On 05/01/2022 15:55, Daniel P. Berrangé wrote:
>>> On Wed, Jan 05, 2022 at 03:49:12PM +0100, Laurent Vivier wrote:
>>>> On 05/01/2022 13:38, Daniel P. Berrangé wrote:
>>>>> The -device JSON syntax impl leaks a reference on the created
>>>>> DeviceState instance. As a result when you hot-unplug the
>>>>> device, the device_finalize method won't be called and thus
>>>>> it will fail to emit the required DEVICE_DELETED event.
>>>>>
>>>>> A 'json-cli' feature was previously added against the
>>>>> 'device_add' QMP command QAPI schema to indicated to mgmt
>>>>> apps that -device supported JSON syntax. Given the hotplug
>>>>> bug that feature flag is no unusable for its purpose, so
>>>>
>>>> Not sure to understand: do you mean "now unusable"?
>>>
>>> An application wants to known whether QEMU can support JSON
>>> syntax with -device. If they look for the 'json-cli' feature
>>> as a witness, they'll end up using JSON with QEMU 6.2 which
>>> is giving them broken hotplug. This is unusable for any
>>> non-trivial use cases. So we need a new witness to indicate
>>> whether JSON is viable with -device, that only the newly
>>> fixed QEMU will report.
>>
>> I understand that, my problem was with your sentence:
>>
>> "Given the hotplug bug that feature flag is no unusable for its purpose"
> 
> What's the problem with that ? It is reasonabled to say a -device impl
> which is broken for hotplug is not usable for non-toy use cases.

So it should be "not usable" instead of "no usable" in the commit description.

  Thomas