Re: [Qemu-block] [RFC PATCH 3/5] job: Drop AioContext lock around aio_poll()

[Fam Zheng]

On Fri, 08/17 19:02, Kevin Wolf wrote:
> Simimlar to AIO_WAIT_WHILE(), job_finish_sync() needs to release the
> AioContext lock of the job before calling aio_poll(). Otherwise,
> callbacks called by aio_poll() would possibly take the lock a second
> time and run into a deadlock with a nested AIO_WAIT_WHILE() call.
> 
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
>  job.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/job.c b/job.c
> index a746bfe70b..6acf55bceb 100644
> --- a/job.c
> +++ b/job.c
> @@ -1016,7 +1016,10 @@ int job_finish_sync(Job *job, void (*finish)(Job *, 
> Error **errp), Error **errp)
>          job_drain(job);
>      }
>      while (!job_is_completed(job)) {
> +        AioContext *aio_context = job->aio_context;
> +        aio_context_release(aio_context);
>          aio_poll(qemu_get_aio_context(), true);
> +        aio_context_acquire(aio_context);
>      }
>      ret = (job_is_cancelled(job) && job->ret == 0) ? -ECANCELED : job->ret;
>      job_unref(job);

Why doesn't this function just use AIO_WAIT_WHILE()?

Fam