Re: [RFC 1/8] memory: Allow eventfd add/del without starting a transaction

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Thu, Mar 25, 2021 at 04:07:28PM +0100, Greg Kurz wrote:
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 5728a681b27d..98ed552e001c 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -1848,13 +1848,25 @@ void memory_region_clear_flush_coalesced(MemoryRegion *mr);
>   * @match_data: whether to match against @data, instead of just @addr
>   * @data: the data to match against the guest write
>   * @e: event notifier to be triggered when @addr, @size, and @data all match.
> + * @transaction: whether to start a transaction for the change

"start" is unclear. Does it begin a transaction and return with the
transaction unfinished? I think instead the function performs the
eventfd addition within a transaction. It would be nice to clarify this.

>   **/
> -void memory_region_add_eventfd(MemoryRegion *mr,
> -                               hwaddr addr,
> -                               unsigned size,
> -                               bool match_data,
> -                               uint64_t data,
> -                               EventNotifier *e);
> +void memory_region_add_eventfd_full(MemoryRegion *mr,
> +                                    hwaddr addr,
> +                                    unsigned size,
> +                                    bool match_data,
> +                                    uint64_t data,
> +                                    EventNotifier *e,
> +                                    bool transaction);
> +
> +static inline void memory_region_add_eventfd(MemoryRegion *mr,
> +                                             hwaddr addr,
> +                                             unsigned size,
> +                                             bool match_data,
> +                                             uint64_t data,
> +                                             EventNotifier *e)
> +{
> +    memory_region_add_eventfd_full(mr, addr, size, match_data, data, e, true);
> +}
>  
>  /**
>   * memory_region_del_eventfd: Cancel an eventfd.
> @@ -1868,13 +1880,25 @@ void memory_region_add_eventfd(MemoryRegion *mr,
>   * @match_data: whether to match against @data, instead of just @addr
>   * @data: the data to match against the guest write
>   * @e: event notifier to be triggered when @addr, @size, and @data all match.
> + * @transaction: whether to start a transaction for the change

Same here.

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