Commit 59811faa authored by David Arinzon's avatar David Arinzon Committed by David S. Miller
Browse files

net: ena: Use bitmask to indicate packet redirection 



Redirecting packets with XDP Redirect is done in two phases:
1. A packet is passed by the driver to the kernel using
   xdp_do_redirect().
2. After finishing polling for new packets the driver lets the kernel
   know that it can now process the redirected packet using
   xdp_do_flush_map().
   The packets' redirection is handled in the napi context of the
   queue that called xdp_do_redirect()

To avoid calling xdp_do_flush_map() each time the driver first checks
whether any packets were redirected, using
	xdp_flags |= xdp_verdict;
and
	if (xdp_flags & XDP_REDIRECT)
	    xdp_do_flush_map()

essentially treating XDP instructions as a bitmask, which isn't the case:
    enum xdp_action {
	    XDP_ABORTED = 0,
	    XDP_DROP,
	    XDP_PASS,
	    XDP_TX,
	    XDP_REDIRECT,
    };

Given the current possible values of xdp_action, the current design
doesn't have a bug (since XDP_REDIRECT = 100b), but it is still
flawed.

This patch makes the driver use a bitmask instead, to avoid future
issues.

Fixes: a318c70a ("net: ena: introduce XDP redirect implementation")
Signed-off-by: default avatarShay Agroskin <shayagr@amazon.com>
Signed-off-by: default avatarDavid Arinzon <darinzon@amazon.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c7f5e34d

drivers/net/ethernet/amazon/ena/ena_netdev.c

+16 −10
Original line number Diff line number Diff line
@@ -374,9 +374,9 @@ static int ena_xdp_xmit(struct net_device *dev, int n, 


static int ena_xdp_execute(struct ena_ring *rx_ring, struct xdp_buff *xdp)

{

	u32 verdict = ENA_XDP_PASS;

	struct bpf_prog *xdp_prog;

	struct ena_ring *xdp_ring;

	u32 verdict = XDP_PASS;

	struct xdp_frame *xdpf;

	u64 *xdp_stat;
@@ -393,7 +393,7 @@ static int ena_xdp_execute(struct ena_ring *rx_ring, struct xdp_buff *xdp) 
		if (unlikely(!xdpf)) {

			trace_xdp_exception(rx_ring->netdev, xdp_prog, verdict);

			xdp_stat = &rx_ring->rx_stats.xdp_aborted;

			verdict = XDP_ABORTED;

			verdict = ENA_XDP_DROP;

			break;

		}
@@ -409,29 +409,35 @@ static int ena_xdp_execute(struct ena_ring *rx_ring, struct xdp_buff *xdp) 


		spin_unlock(&xdp_ring->xdp_tx_lock);

		xdp_stat = &rx_ring->rx_stats.xdp_tx;

		verdict = ENA_XDP_TX;

		break;

	case XDP_REDIRECT:

		if (likely(!xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog))) {

			xdp_stat = &rx_ring->rx_stats.xdp_redirect;

			verdict = ENA_XDP_REDIRECT;

			break;

		}

		trace_xdp_exception(rx_ring->netdev, xdp_prog, verdict);

		xdp_stat = &rx_ring->rx_stats.xdp_aborted;

		verdict = XDP_ABORTED;

		verdict = ENA_XDP_DROP;

		break;

	case XDP_ABORTED:

		trace_xdp_exception(rx_ring->netdev, xdp_prog, verdict);

		xdp_stat = &rx_ring->rx_stats.xdp_aborted;

		verdict = ENA_XDP_DROP;

		break;

	case XDP_DROP:

		xdp_stat = &rx_ring->rx_stats.xdp_drop;

		verdict = ENA_XDP_DROP;

		break;

	case XDP_PASS:

		xdp_stat = &rx_ring->rx_stats.xdp_pass;

		verdict = ENA_XDP_PASS;

		break;

	default:

		bpf_warn_invalid_xdp_action(rx_ring->netdev, xdp_prog, verdict);

		xdp_stat = &rx_ring->rx_stats.xdp_invalid;

		verdict = ENA_XDP_DROP;

	}



	ena_increase_stat(xdp_stat, 1, &rx_ring->syncp);
@@ -1621,12 +1627,12 @@ static int ena_xdp_handle_buff(struct ena_ring *rx_ring, struct xdp_buff *xdp) 
	 * we expect, then we simply drop it

	 */

	if (unlikely(rx_ring->ena_bufs[0].len > ENA_XDP_MAX_MTU))

		return XDP_DROP;

		return ENA_XDP_DROP;



	ret = ena_xdp_execute(rx_ring, xdp);



	/* The xdp program might expand the headers */

	if (ret == XDP_PASS) {

	if (ret == ENA_XDP_PASS) {

		rx_info->page_offset = xdp->data - xdp->data_hard_start;

		rx_ring->ena_bufs[0].len = xdp->data_end - xdp->data;

	}
@@ -1665,7 +1671,7 @@ static int ena_clean_rx_irq(struct ena_ring *rx_ring, struct napi_struct *napi, 
	xdp_init_buff(&xdp, ENA_PAGE_SIZE, &rx_ring->xdp_rxq);



	do {

		xdp_verdict = XDP_PASS;

		xdp_verdict = ENA_XDP_PASS;

		skb = NULL;

		ena_rx_ctx.ena_bufs = rx_ring->ena_bufs;

		ena_rx_ctx.max_bufs = rx_ring->sgl_size;
@@ -1693,7 +1699,7 @@ static int ena_clean_rx_irq(struct ena_ring *rx_ring, struct napi_struct *napi, 
			xdp_verdict = ena_xdp_handle_buff(rx_ring, &xdp);



		/* allocate skb and fill it */

		if (xdp_verdict == XDP_PASS)

		if (xdp_verdict == ENA_XDP_PASS)

			skb = ena_rx_skb(rx_ring,

					 rx_ring->ena_bufs,

					 ena_rx_ctx.descs,
@@ -1711,13 +1717,13 @@ static int ena_clean_rx_irq(struct ena_ring *rx_ring, struct napi_struct *napi, 
				/* Packets was passed for transmission, unmap it

				 * from RX side.

				 */

				if (xdp_verdict == XDP_TX || xdp_verdict == XDP_REDIRECT) {

				if (xdp_verdict & ENA_XDP_FORWARDED) {

					ena_unmap_rx_buff(rx_ring,

							  &rx_ring->rx_buffer_info[req_id]);

					rx_ring->rx_buffer_info[req_id].page = NULL;

				}

			}

			if (xdp_verdict != XDP_PASS) {

			if (xdp_verdict != ENA_XDP_PASS) {

				xdp_flags |= xdp_verdict;

				total_len += ena_rx_ctx.ena_bufs[0].len;

				res_budget--;
@@ -1763,7 +1769,7 @@ static int ena_clean_rx_irq(struct ena_ring *rx_ring, struct napi_struct *napi, 
		ena_refill_rx_bufs(rx_ring, refill_required);

	}



	if (xdp_flags & XDP_REDIRECT)

	if (xdp_flags & ENA_XDP_REDIRECT)

		xdp_do_flush_map();



	return work_done;

drivers/net/ethernet/amazon/ena/ena_netdev.h

+9 −0
Original line number Diff line number Diff line
@@ -409,6 +409,15 @@ enum ena_xdp_errors_t { 
	ENA_XDP_NO_ENOUGH_QUEUES,

};



enum ENA_XDP_ACTIONS {

	ENA_XDP_PASS		= 0,

	ENA_XDP_TX		= BIT(0),

	ENA_XDP_REDIRECT	= BIT(1),

	ENA_XDP_DROP		= BIT(2)

};



#define ENA_XDP_FORWARDED (ENA_XDP_TX | ENA_XDP_REDIRECT)



static inline bool ena_xdp_present(struct ena_adapter *adapter)

{

	return !!adapter->xdp_bpf_prog;