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

3 files changed, 16 insertions, 23 deletions

diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
index fd966567464c..074702af3dc6 100644
--- a/drivers/net/ethernet/ti/cpsw.c
+++ b/drivers/net/ethernet/ti/cpsw.c
@@ -1123,25 +1123,23 @@ static int cpsw_ndo_xdp_xmit(struct net_device *ndev, int n,
 	struct cpsw_priv *priv = netdev_priv(ndev);
 	struct cpsw_common *cpsw = priv->cpsw;
 	struct xdp_frame *xdpf;
-	int i, drops = 0, port;
+	int i, nxmit = 0, port;
 
 	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
 		return -EINVAL;
 
 	for (i = 0; i < n; i++) {
 		xdpf = frames[i];
-		if (xdpf->len < CPSW_MIN_PACKET_SIZE) {
-			xdp_return_frame_rx_napi(xdpf);
-			drops++;
-			continue;
-		}
+		if (xdpf->len < CPSW_MIN_PACKET_SIZE)
+			break;
 
 		port = priv->emac_port + cpsw->data.dual_emac;
 		if (cpsw_xdp_tx_frame(priv, xdpf, NULL, port))
-			drops++;
+			break;
+		nxmit++;
 	}
 
-	return n - drops;
+	return nxmit;
 }
 
 #ifdef CONFIG_NET_POLL_CONTROLLER
diff --git a/drivers/net/ethernet/ti/cpsw_new.c b/drivers/net/ethernet/ti/cpsw_new.c
index 58a64313ac00..0751f77de2c7 100644
--- a/drivers/net/ethernet/ti/cpsw_new.c
+++ b/drivers/net/ethernet/ti/cpsw_new.c
@@ -1093,24 +1093,22 @@ static int cpsw_ndo_xdp_xmit(struct net_device *ndev, int n,
 {
 	struct cpsw_priv *priv = netdev_priv(ndev);
 	struct xdp_frame *xdpf;
-	int i, drops = 0;
+	int i, nxmit = 0;
 
 	if (unlikely(flags & ~XDP_XMIT_FLAGS_MASK))
 		return -EINVAL;
 
 	for (i = 0; i < n; i++) {
 		xdpf = frames[i];
-		if (xdpf->len < CPSW_MIN_PACKET_SIZE) {
-			xdp_return_frame_rx_napi(xdpf);
-			drops++;
-			continue;
-		}
+		if (xdpf->len < CPSW_MIN_PACKET_SIZE)
+			break;
 
 		if (cpsw_xdp_tx_frame(priv, xdpf, NULL, priv->emac_port))
-			drops++;
+			break;
+		nxmit++;
 	}
 
-	return n - drops;
+	return nxmit;
 }
 
 static int cpsw_get_port_parent_id(struct net_device *ndev,
diff --git a/drivers/net/ethernet/ti/cpsw_priv.c b/drivers/net/ethernet/ti/cpsw_priv.c
index bb59e768915e..5862f0a4a975 100644
--- a/drivers/net/ethernet/ti/cpsw_priv.c
+++ b/drivers/net/ethernet/ti/cpsw_priv.c
@@ -1305,19 +1305,15 @@ int cpsw_xdp_tx_frame(struct cpsw_priv *priv, struct xdp_frame *xdpf,
 		ret = cpdma_chan_submit_mapped(txch, cpsw_xdpf_to_handle(xdpf),
 					       dma, xdpf->len, port);
 	} else {
-		if (sizeof(*xmeta) > xdpf->headroom) {
-			xdp_return_frame_rx_napi(xdpf);
+		if (sizeof(*xmeta) > xdpf->headroom)
 			return -EINVAL;
-		}
 
 		ret = cpdma_chan_submit(txch, cpsw_xdpf_to_handle(xdpf),
 					xdpf->data, xdpf->len, port);
 	}
 
-	if (ret) {
+	if (ret)
 		priv->ndev->stats.tx_dropped++;
-		xdp_return_frame_rx_napi(xdpf);
-	}
 
 	return ret;
 }
@@ -1353,7 +1349,8 @@ int cpsw_run_xdp(struct cpsw_priv *priv, int ch, struct xdp_buff *xdp,
 		if (unlikely(!xdpf))
 			goto drop;
 
-		cpsw_xdp_tx_frame(priv, xdpf, page, port);
+		if (cpsw_xdp_tx_frame(priv, xdpf, page, port))
+			xdp_return_frame_rx_napi(xdpf);
 		break;
 	case XDP_REDIRECT:
 		if (xdp_do_redirect(ndev, xdp, prog))