Re: [PATCH v4 3/6] block-copy: improve comments of BlockCopyTask and BlockCopyState types and functions

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

14.06.2021 10:33, Emanuele Giuseppe Esposito wrote:
> As done in BlockCopyCallState, categorize BlockCopyTask
> and BlockCopyState in IN, State and OUT fields.
> This is just to understand which field has to be protected with a lock.
> 
> .sleep_state is handled in the series "coroutine: new sleep/wake API"
> and thus here left as TODO.
> 
> Signed-off-by: Emanuele Giuseppe Esposito<eesposit@redhat.com>
> ---
>   block/block-copy.c | 49 +++++++++++++++++++++++++++++-----------------
>   1 file changed, 31 insertions(+), 18 deletions(-)
> 
> diff --git a/block/block-copy.c b/block/block-copy.c
> index 3f26be8ddc..5ff7764e87 100644
> --- a/block/block-copy.c
> +++ b/block/block-copy.c
> @@ -52,29 +52,35 @@ typedef struct BlockCopyCallState {
>       /* Coroutine where async block-copy is running */
>       Coroutine *co;
>   
> -    /* To reference all call states from BlockCopyState */
> -    QLIST_ENTRY(BlockCopyCallState) list;
> -
>       /* State */
> -    int ret;
>       bool finished;
> -    QemuCoSleep sleep;
> -    bool cancelled;
> +    QemuCoSleep sleep; /* TODO: protect API with a lock */
> +
> +    /* To reference all call states from BlockCopyState */
> +    QLIST_ENTRY(BlockCopyCallState) list;
>   
>       /* OUT parameters */
> +    bool cancelled;

actually, cancelled is not OUT field. It's set by user to cancel the operation. And block-copy tracks the field to understand should it cancel at the moment or not. So, it's part of state.

Also, I just now understand, that "out parameter" sounds strange here. As "parameter" is an input by general meaning.. We may have "out parameters" for functions, as all parameters of a function are generally called "parameters" anyway. I think "OUT fields" is more correct here. I don't insist, as I'm not an expert in English (for sure, you'll find mistakes even in this paragraph :\

-- 
Best regards,
Vladimir