Re: [PATCH 04/11] job: add .cancel handler for the driver

[Eric Blake]

On 11/18/20 12:04 PM, Vladimir Sementsov-Ogievskiy wrote:
> To be used in mirror in the following commit to cancel in-flight io on
> target to not waste the time.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  include/qemu/job.h | 5 +++++
>  job.c              | 3 +++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/include/qemu/job.h b/include/qemu/job.h
> index 32aabb1c60..efc6fa7544 100644
> --- a/include/qemu/job.h
> +++ b/include/qemu/job.h
> @@ -251,6 +251,11 @@ struct JobDriver {
>       */
>      void (*clean)(Job *job);
>  
> +    /**
> +     * If the callback is not NULL, it will be invoked in job_cancel_async
> +     */
> +    void (*cancel)(Job *job);
> +

Does the call need to be re-entrant or even worry about being invoked
more than once on the same BDS?  Or worded differently,

> +++ b/job.c
> @@ -712,6 +712,9 @@ static int job_finalize_single(Job *job)
>  
>  static void job_cancel_async(Job *job, bool force)
>  {
> +    if (job->driver->cancel) {
> +        job->driver->cancel(job);
> +    }
>      if (job->user_paused) {

can job_cancel_async be reached more than once on the same BDS?

>          /* Do not call job_enter here, the caller will handle it.  */
>          if (job->driver->user_resume) {
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org