On Fri, 2016-09-09 at 14:29 -0700, John Fastabend wrote:
> From: Alexei Starovoitov <[email protected]>
>
So it looks like e1000_xmit_raw_frame() can return early,
say if there is no available descriptor.
> +static void e1000_xmit_raw_frame(struct e1000_rx_buffer *rx_buffer_info,
> + unsigned int len,
> + struct net_device *netdev,
> + struct e1000_adapter *adapter)
> +{
> + struct netdev_queue *txq = netdev_get_tx_queue(netdev, 0);
> + struct e1000_hw *hw = &adapter->hw;
> + struct e1000_tx_ring *tx_ring;
> +
> + if (len > E1000_MAX_DATA_PER_TXD)
> + return;
> +
> + /* e1000 only support a single txq at the moment so the queue is being
> + * shared with stack. To support this requires locking to ensure the
> + * stack and XDP are not running at the same time. Devices with
> + * multiple queues should allocate a separate queue space.
> + */
> + HARD_TX_LOCK(netdev, txq, smp_processor_id());
> +
> + tx_ring = adapter->tx_ring;
> +
> + if (E1000_DESC_UNUSED(tx_ring) < 2) {
> + HARD_TX_UNLOCK(netdev, txq);
> + return;
> + }
> +
> + e1000_tx_map_rxpage(tx_ring, rx_buffer_info, len);
> + e1000_tx_queue(adapter, tx_ring, 0/*tx_flags*/, 1);
> +
> + writel(tx_ring->next_to_use, hw->hw_addr + tx_ring->tdt);
> + mmiowb();
> +
> + HARD_TX_UNLOCK(netdev, txq);
> +}
> +
> #define NUM_REGS 38 /* 1 based count */
> static void e1000_regdump(struct e1000_adapter *adapter)
> {
> @@ -4142,6 +4247,19 @@ static struct sk_buff *e1000_alloc_rx_skb(struct
> e1000_adapter *adapter,
> return skb;
> }
> + act = e1000_call_bpf(prog, page_address(p), length);
> + switch (act) {
> + case XDP_PASS:
> + break;
> + case XDP_TX:
> + dma_sync_single_for_device(&pdev->dev,
> + dma,
> + length,
> + DMA_TO_DEVICE);
> + e1000_xmit_raw_frame(buffer_info, length,
> + netdev, adapter);
> + buffer_info->rxbuf.page = NULL;
So I am trying to understand how pages are not leaked ?
