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

[Markus Armbruster <armbru@redhat.com>]

Daniel P. Berrangé <berrange@redhat.com> writes:

> 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

As Laurent and Thomas pointed out, this should be "is not usable" or "is
unusable".

> we add a new 'json-cli-hotplug' feature to indicate the
> -device supports JSON without breaking hotplug.
>
> Fixes: https://gitlab.com/qemu-project/qemu/-/issues/802
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  qapi/qdev.json                 |  5 ++++-
>  softmmu/vl.c                   |  4 +++-
>  tests/qtest/device-plug-test.c | 19 +++++++++++++++++++
>  3 files changed, 26 insertions(+), 2 deletions(-)
>
> diff --git a/qapi/qdev.json b/qapi/qdev.json
> index 69656b14df..26cd10106b 100644
> --- a/qapi/qdev.json
> +++ b/qapi/qdev.json
> @@ -44,6 +44,9 @@
>  # @json-cli: If present, the "-device" command line option supports JSON
>  #            syntax with a structure identical to the arguments of this
>  #            command.
> +# @json-cli-hotplug: If present, the "-device" command line option supports JSON
> +#                    syntax without the reference counting leak that broke
> +#                    hot-unplug

For local consistency, please end the sentence with a period and wrap
lines like so:

   # @json-cli-hotplug: If present, the "-device" command line option supports
   #                    JSON syntax without the reference counting leak that
   #                    broke hot-unplug.

>  #
>  # Notes:
>  #
> @@ -74,7 +77,7 @@
>  { 'command': 'device_add',
>    'data': {'driver': 'str', '*bus': 'str', '*id': 'str'},
>    'gen': false, # so we can get the additional arguments
> -  'features': ['json-cli'] }
> +  'features': ['json-cli', 'json-cli-hotplug'] }
>  
>  ##
>  # @device_del:

Kevin, I hope you can apply these touch-ups in your tree.  Then, QAPI
schema
Acked-by: Markus Armbruster <armbru@redhat.com>

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