Re: [PATCH v3 4/4] block: Mark 'block_resize' as coroutine

From: Markus Armbruster <armbru@redhat.com>
To: Kevin Wolf <kwolf@redhat.com>
Cc: stefanha@redhat.com, marcandre.lureau@gmail.com,
	qemu-devel@nongnu.org, qemu-block@nongnu.org
Subject: Re: [PATCH v3 4/4] block: Mark 'block_resize' as coroutine
Date: Thu, 16 Jan 2020 10:45:40 +0100	[thread overview]
Message-ID: <87tv4vzqd7.fsf@dusky.pond.sub.org> (raw)
In-Reply-To: <20200115122326.26393-5-kwolf@redhat.com> (Kevin Wolf's message of "Wed, 15 Jan 2020 13:23:26 +0100")

Kevin Wolf <kwolf@redhat.com> writes:

> block_resize is safe to run in a coroutine, so use it as an example for
> the new 'coroutine': true annotation in the QAPI schema.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> ---
>  qapi/block-core.json | 3 ++-
>  blockdev.c           | 6 +++---
>  2 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/qapi/block-core.json b/qapi/block-core.json
> index 7ff5e5edaf..1dbb2a9901 100644
> --- a/qapi/block-core.json
> +++ b/qapi/block-core.json
> @@ -1341,7 +1341,8 @@
>  { 'command': 'block_resize',
>    'data': { '*device': 'str',
>              '*node-name': 'str',
> -            'size': 'int' } }
> +            'size': 'int' },
> +  'coroutine': true }
>  
>  ##
>  # @NewImageMode:
> diff --git a/blockdev.c b/blockdev.c
> index 8e029e9c01..b5e5d1e072 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -3161,9 +3161,9 @@ void hmp_drive_del(Monitor *mon, const QDict *qdict)
>      aio_context_release(aio_context);
>  }
>  
> -void qmp_block_resize(bool has_device, const char *device,
> -                      bool has_node_name, const char *node_name,
> -                      int64_t size, Error **errp)
> +void coroutine_fn qmp_block_resize(bool has_device, const char *device,
> +                                   bool has_node_name, const char *node_name,
> +                                   int64_t size, Error **errp)
>  {
>      Error *local_err = NULL;
>      BlockBackend *blk = NULL;

Pardon my ignorant question: what exactly makes a function a
coroutine_fn?