Cleaned up implementation of netfront.c:network_rx()

gistfile1.c

void network_rx(struct netfront_dev *dev)
{
    RING_IDX i, resp_prod, req_prod;
    int more_to_do, nr_consumed, notify;

    nr_consumed = 0;
again:
    resp_prod = dev->rx.sring->rsp_prod;
    rmb(); /* Ensure we see queued responses up to 'resp_prod'. */

    for (i = dev->rx.rsp_cons; i != resp_prod; i++, nr_consumed++)
    {
        struct netif_rx_response *rx = RING_GET_RESPONSE(&dev->rx, i);
        struct net_buffer* buf;
        unsigned char* page;
        
        BUG_ON(rx->id >= NET_RX_RING_SIZE);

        buf = &dev->rx_buffers[rx->id];
        page = (unsigned char*)buf->page;
        gnttab_end_access(buf->gref);
        if (rx->status > 0)
            dev->netif_rx(dev, page + rx->offset, rx->status);
    }

    rmb();
    dev->rx.rsp_cons = i;
    RING_FINAL_CHECK_FOR_RESPONSES(&dev->rx, more_to_do);
    if (more_to_do)
        goto again;

    /* We must push the same amount of request slots onto the ring as we 
     * consumed in this run, otherwise they will eventually run out. */
    req_prod = dev->rx.req_prod_pvt;
    for(i=0; i < nr_consumed; i++)
    {
        int id = xennet_rxidx(req_prod + i);
        netif_rx_request_t *req = RING_GET_REQUEST(&dev->rx, req_prod + i);
        struct net_buffer* buf = &dev->rx_buffers[id];
        void* page = buf->page;
        req->id = id;

        /* We are sure to have free gnttab entries since they got released above */
        buf->gref = req->gref = 
            gnttab_grant_access(dev->dom, virt_to_mfn(page),0);
    }

    wmb();
    dev->rx.req_prod_pvt = req_prod + i;
    
    RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&dev->rx, notify);
    if (notify)
        notify_remote_via_evtchn(dev->evtchn);
}