Re: [PATCH] as i/o hang with aacraid driver 2.6.0-test1

[Daniel McNeil <daniel@osdl.org>]

On Thu, 2003-07-17 at 15:39, Mark Haverkamp wrote:
> 
> ===== drivers/block/as-iosched.c 1.5 vs edited =====
> --- 1.5/drivers/block/as-iosched.c	Sat Jul 12 04:28:01 2003
> +++ edited/drivers/block/as-iosched.c	Thu Jul 17 15:31:27 2003
> @@ -1306,6 +1306,29 @@
>  	as_update_arq(ad, arq); /* keep state machine up to date */
>  }
>  
> +/*
> + * requeue the request. The request has not been completed, nor is it a
> + * new request, so don't touch accounting.
> + */
> +static void as_requeue_request(request_queue_t *q, struct request *rq)
> +{
> +	struct as_data *ad = q->elevator.elevator_data;
> +	struct as_rq *arq = RQ_DATA(rq);
> +
> +	if (arq && arq->io_context && arq->io_context->aic)
> +		atomic_inc(&arq->io_context->aic->nr_dispatched);
> +
> +	list_add(&rq->queuelist, ad->dispatch->prev);
> +
> +	/* Stop anticipating - let this request get through */
> +	if (!list_empty(ad->dispatch)
> +		&& (ad->antic_status == ANTIC_WAIT_REQ
> +			|| ad->antic_status == ANTIC_WAIT_NEXT))
> +		as_antic_stop(ad);
> +
> +	return;
> +}
> +

2 questions:

Should	
	list_add(&rq->queuelist, ad->dispatch->prev);
be
	list_add_tail(&rq->queuelist, ad->dispatch);

It is equivalent, but makes the code clearer that we're adding to the
end.

Also, isn't the: !list_empty(ad->dispatch) unnecessary since a
list_add was just done, so the list cannot be empty?

Daniel <daniel@osdl.org>