Re: [Qemu-devel] [PATCH 10/14] qio: refcount QIOTask

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Feb 28, 2018 at 01:06:29PM +0800, Peter Xu wrote:
> It will be used in multiple threads in follow-up patches.  Let it start
> to have refcounts.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  include/io/task.h |  3 +++
>  io/task.c         | 23 ++++++++++++++++++++++-
>  2 files changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/include/io/task.h b/include/io/task.h
> index 9dbe3758d7..c6acd6489c 100644
> --- a/include/io/task.h
> +++ b/include/io/task.h
> @@ -322,4 +322,7 @@ gpointer qio_task_get_result_pointer(QIOTask *task);
>   */
>  Object *qio_task_get_source(QIOTask *task);
>  
> +void qio_task_ref(QIOTask *task);
> +void qio_task_unref(QIOTask *task);

It should just be turned back into a QObject as it was originally,
so we get refcounting for free.

> diff --git a/io/task.c b/io/task.c
> index 204c0be286..00d3a5096a 100644
> --- a/io/task.c
> +++ b/io/task.c
> @@ -32,6 +32,7 @@ struct QIOTask {
>      Error *err;
>      gpointer result;
>      GDestroyNotify destroyResult;
> +    uint32_t refcount;
>  
>      /* Threaded QIO task specific fields */
>      GSource *idle_source;  /* The idle task to run complete routine */
> @@ -57,6 +58,8 @@ QIOTask *qio_task_new(Object *source,
>  
>      trace_qio_task_new(task, source, func, opaque);
>  
> +    qio_task_ref(task);
> +
>      return task;
>  }
>  
> @@ -165,7 +168,7 @@ void qio_task_complete(QIOTask *task)
>  {
>      task->func(task, task->opaque);
>      trace_qio_task_complete(task);
> -    qio_task_free(task);
> +    qio_task_unref(task);
>  }
>  
>  
> @@ -208,3 +211,21 @@ Object *qio_task_get_source(QIOTask *task)
>  {
>      return task->source;
>  }
> +
> +void qio_task_ref(QIOTask *task)
> +{
> +    if (!task) {
> +        return;
> +    }
> +    atomic_inc(&task->refcount);
> +}
> +
> +void qio_task_unref(QIOTask *task)
> +{
> +    if (!task) {
> +        return;
> +    }
> +    if (atomic_fetch_dec(&task->refcount) == 1) {
> +        qio_task_free(task);
> +    }
> +}
> -- 
> 2.14.3
> 

Regards,
Daniel
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