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, 8 insertions, 12 deletions

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
index 641303894341..ec9564e584e0 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_xdp.c
@@ -217,7 +217,7 @@ int bnxt_xdp_xmit(struct net_device *dev, int num_frames,
 	struct pci_dev *pdev = bp->pdev;
 	struct bnxt_tx_ring_info *txr;
 	dma_addr_t mapping;
-	int drops = 0;
+	int nxmit = 0;
 	int ring;
 	int i;
 
@@ -233,21 +233,17 @@ int bnxt_xdp_xmit(struct net_device *dev, int num_frames,
 		struct xdp_frame *xdp = frames[i];
 
 		if (!txr || !bnxt_tx_avail(bp, txr) ||
-		    !(bp->bnapi[ring]->flags & BNXT_NAPI_FLAG_XDP)) {
-			xdp_return_frame_rx_napi(xdp);
-			drops++;
-			continue;
-		}
+		    !(bp->bnapi[ring]->flags & BNXT_NAPI_FLAG_XDP))
+			break;
 
 		mapping = dma_map_single(&pdev->dev, xdp->data, xdp->len,
 					 DMA_TO_DEVICE);
 
-		if (dma_mapping_error(&pdev->dev, mapping)) {
-			xdp_return_frame_rx_napi(xdp);
-			drops++;
-			continue;
-		}
+		if (dma_mapping_error(&pdev->dev, mapping))
+			break;
+
 		__bnxt_xmit_xdp_redirect(bp, txr, mapping, xdp->len, xdp);
+		nxmit++;
 	}
 
 	if (flags & XDP_XMIT_FLUSH) {
@@ -256,7 +252,7 @@ int bnxt_xdp_xmit(struct net_device *dev, int num_frames,
 		bnxt_db_write(bp, &txr->tx_db, txr->tx_prod);
 	}
 
-	return num_frames - drops;
+	return nxmit;
 }
 
 /* Under rtnl_lock */