bpf, devmap: Move drop error path to devmap for XDP_REDIRECT

We want to change the current ndo_xdp_xmit drop semantics because it will
allow us to implement better queue overflow handling. This is working
towards the larger goal of a XDP TX queue-hook. Move XDP_REDIRECT error
path handling from each XDP ethernet driver to devmap code. According to
the new APIs, the driver running the ndo_xdp_xmit pointer, will break tx
loop whenever the hw reports a tx error and it will just return to devmap
caller the number of successfully transmitted frames. It will be devmap
responsibility to free dropped frames.

Move each XDP ndo_xdp_xmit capable driver to the new APIs:

- veth
- virtio-net
- mvneta
- mvpp2
- socionext
- amazon ena
- bnxt
- freescale (dpaa2, dpaa)
- xen-frontend
- qede
- ice
- igb
- ixgbe
- i40e
- mlx5
- ti (cpsw, cpsw-new)
- tun
- sfc

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Camelia Groza <camelia.groza@nxp.com>
Acked-by: Edward Cree <ecree.xilinx@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Shay Agroskin <shayagr@amazon.com>
Link: https://lore.kernel.org/bpf/ed670de24f951cfd77590decf0229a0ad7fd12f6.1615201152.git.lorenzo@kernel.org

1 files changed, 9 insertions, 12 deletions

diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
index 102f2c91fdb8..5c062c51b4cb 100644
--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -300,7 +300,7 @@ static int ena_xdp_xmit_frame(struct ena_ring *xdp_ring,
 
 	rc = ena_xdp_tx_map_frame(xdp_ring, tx_info, xdpf, &push_hdr, &push_len);
 	if (unlikely(rc))
-		goto error_drop_packet;
+		return rc;
 
 	ena_tx_ctx.ena_bufs = tx_info->bufs;
 	ena_tx_ctx.push_header = push_hdr;
@@ -330,8 +330,6 @@ static int ena_xdp_xmit_frame(struct ena_ring *xdp_ring,
 error_unmap_dma:
 	ena_unmap_tx_buff(xdp_ring, tx_info);
 	tx_info->xdpf = NULL;
-error_drop_packet:
-	xdp_return_frame(xdpf);
 	return rc;
 }
 
@@ -339,8 +337,8 @@ static int ena_xdp_xmit(struct net_device *dev, int n,
 			struct xdp_frame **frames, u32 flags)
 {
 	struct ena_adapter *adapter = netdev_priv(dev);
-	int qid, i, err, drops = 0;
 	struct ena_ring *xdp_ring;
+	int qid, i, nxmit = 0;
 
 	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
 		return -EINVAL;
@@ -360,12 +358,9 @@ static int ena_xdp_xmit(struct net_device *dev, int n,
 	spin_lock(&xdp_ring->xdp_tx_lock);
 
 	for (i = 0; i < n; i++) {
-		err = ena_xdp_xmit_frame(xdp_ring, dev, frames[i], 0);
-		/* The descriptor is freed by ena_xdp_xmit_frame in case
-		 * of an error.
-		 */
-		if (err)
-			drops++;
+		if (ena_xdp_xmit_frame(xdp_ring, dev, frames[i], 0))
+			break;
+		nxmit++;
 	}
 
 	/* Ring doorbell to make device aware of the packets */
@@ -378,7 +373,7 @@ static int ena_xdp_xmit(struct net_device *dev, int n,
 	spin_unlock(&xdp_ring->xdp_tx_lock);
 
 	/* Return number of packets sent */
-	return n - drops;
+	return nxmit;
 }
 
 static int ena_xdp_execute(struct ena_ring *rx_ring, struct xdp_buff *xdp)
@@ -415,7 +410,9 @@ static int ena_xdp_execute(struct ena_ring *rx_ring, struct xdp_buff *xdp)
 		/* The XDP queues are shared between XDP_TX and XDP_REDIRECT */
 		spin_lock(&xdp_ring->xdp_tx_lock);
 
-		ena_xdp_xmit_frame(xdp_ring, rx_ring->netdev, xdpf, XDP_XMIT_FLUSH);
+		if (ena_xdp_xmit_frame(xdp_ring, rx_ring->netdev, xdpf,
+				       XDP_XMIT_FLUSH))
+			xdp_return_frame(xdpf);
 
 		spin_unlock(&xdp_ring->xdp_tx_lock);
 		xdp_stat = &rx_ring->rx_stats.xdp_tx;