Re: [Qemu-devel] [PATCH 07/14] aio-wait: Increase num_waiters even in home thread

[Fam Zheng <famz@redhat.com>]

On Fri, 09/07 18:15, Kevin Wolf wrote:
> Even if AIO_WAIT_WHILE() is called in the home context of the
> AioContext, we still want to allow the condition to change depending on
> other threads as long as they kick the AioWait. Specfically block jobs
> can be running in an I/O thread and should then be able to kick a drain
> in the main loop context.

We can now move the atomic_inc/atomic_dec pair outside the if/else block,
but that's cosmetic.

Reviewed-by: Fam Zheng <famz@redhat.com>


> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>  include/block/aio-wait.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/include/block/aio-wait.h b/include/block/aio-wait.h
> index c85a62f798..46ba7f9111 100644
> --- a/include/block/aio-wait.h
> +++ b/include/block/aio-wait.h
> @@ -77,10 +77,12 @@ typedef struct {
>      AioWait *wait_ = (wait);                                       \
>      AioContext *ctx_ = (ctx);                                      \
>      if (ctx_ && in_aio_context_home_thread(ctx_)) {                \
> +        atomic_inc(&wait_->num_waiters);                           \
>          while ((cond)) {                                           \
>              aio_poll(ctx_, true);                                  \
>              waited_ = true;                                        \
>          }                                                          \
> +        atomic_dec(&wait_->num_waiters);                           \
>      } else {                                                       \
>          assert(qemu_get_current_aio_context() ==                   \
>                 qemu_get_aio_context());                            \
> -- 
> 2.13.6
>