Re: [Xen-devel] [PATCH net-next V2 2/3] xen-netback: avoid allocating variable size array on stack

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 02.05.13 at 12:43, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
> @@ -934,11 +934,14 @@ static int netbk_count_requests(struct xenvif *vif,
>       RING_IDX cons = vif->tx.req_cons;
>       int slots = 0;
>       int drop_err = 0;
> +     int more_data;
>  
>       if (!(first->flags & XEN_NETTXF_more_data))
>               return 0;
>  
>       do {
> +             struct xen_netif_tx_request dropped_tx = { 0 };
> +

No need for an initializer here.

>               if (slots >= work_to_do) {
>                       netdev_err(vif->dev,
>                                  "Asked for %d slots but exceeds this 
> limit\n",
> @@ -972,6 +975,9 @@ static int netbk_count_requests(struct xenvif *vif,
>                       drop_err = -E2BIG;
>               }
>  
> +             if (drop_err)
> +                     txp = &dropped_tx;
> +
>               memcpy(txp, RING_GET_REQUEST(&vif->tx, cons + slots),
>                      sizeof(*txp));
>  
> @@ -1001,7 +1007,13 @@ static int netbk_count_requests(struct xenvif *vif,
>                       netbk_fatal_tx_err(vif);
>                       return -EINVAL;
>               }
> -     } while ((txp++)->flags & XEN_NETTXF_more_data);
> +
> +             more_data = txp->flags & XEN_NETTXF_more_data;
> +
> +             if (!drop_err)
> +                     txp++;

And no need for the conditional here afaict.

Jan

> +
> +     } while (more_data);
>  
>       if (drop_err) {
>               netbk_tx_err(vif, first, cons + slots);



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