[PATCH net-next] net: lan966x: Don't use xdp_frame when action is XDP_TX

[Horatiu Vultur <horatiu.vultur@microchip.com>]

When the action of an xdp program was XDP_TX, lan966x was creating
a xdp_frame and use this one to send the frame back. But it is also
possible to send back the frame without needing a xdp_frame, because
it possible to send it back using the page.
And then once the frame is transmitted is possible to use directly
page_pool_recycle_direct as lan966x is using page pools.
This would save some CPU usage on this path.

Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
---
 .../ethernet/microchip/lan966x/lan966x_fdma.c | 35 +++++++++++--------
 .../ethernet/microchip/lan966x/lan966x_main.h |  2 ++
 .../ethernet/microchip/lan966x/lan966x_xdp.c  | 11 +++---
 3 files changed, 27 insertions(+), 21 deletions(-)

diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
index 2ed76bb61a731..7947259e67e4e 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c
@@ -390,6 +390,7 @@ static void lan966x_fdma_stop_netdev(struct lan966x *lan966x)
 static void lan966x_fdma_tx_clear_buf(struct lan966x *lan966x, int weight)
 {
 	struct lan966x_tx *tx = &lan966x->tx;
+	struct lan966x_rx *rx = &lan966x->rx;
 	struct lan966x_tx_dcb_buf *dcb_buf;
 	struct xdp_frame_bulk bq;
 	struct lan966x_db *db;
@@ -432,7 +433,8 @@ static void lan966x_fdma_tx_clear_buf(struct lan966x *lan966x, int weight)
 			if (dcb_buf->xdp_ndo)
 				xdp_return_frame_bulk(dcb_buf->data.xdpf, &bq);
 			else
-				xdp_return_frame_rx_napi(dcb_buf->data.xdpf);
+				page_pool_recycle_direct(rx->page_pool,
+							 dcb_buf->data.page);
 		}
 
 		clear = true;
@@ -702,6 +704,7 @@ static void lan966x_fdma_tx_start(struct lan966x_tx *tx, int next_to_use)
 int lan966x_fdma_xmit_xdpf(struct lan966x_port *port,
 			   struct xdp_frame *xdpf,
 			   struct page *page,
+			   u32 len,
 			   bool dma_map)
 {
 	struct lan966x *lan966x = port->lan966x;
@@ -722,6 +725,15 @@ int lan966x_fdma_xmit_xdpf(struct lan966x_port *port,
 		goto out;
 	}
 
+	/* Fill up the buffer */
+	next_dcb_buf = &tx->dcbs_buf[next_to_use];
+	next_dcb_buf->use_skb = false;
+	next_dcb_buf->xdp_ndo = dma_map;
+	next_dcb_buf->len = len + IFH_LEN_BYTES;
+	next_dcb_buf->used = true;
+	next_dcb_buf->ptp = false;
+	next_dcb_buf->dev = port->dev;
+
 	/* Generate new IFH */
 	if (dma_map) {
 		if (xdpf->headroom < IFH_LEN_BYTES) {
@@ -736,16 +748,18 @@ int lan966x_fdma_xmit_xdpf(struct lan966x_port *port,
 
 		dma_addr = dma_map_single(lan966x->dev,
 					  xdpf->data - IFH_LEN_BYTES,
-					  xdpf->len + IFH_LEN_BYTES,
+					  len + IFH_LEN_BYTES,
 					  DMA_TO_DEVICE);
 		if (dma_mapping_error(lan966x->dev, dma_addr)) {
 			ret = NETDEV_TX_OK;
 			goto out;
 		}
 
+		next_dcb_buf->data.xdpf = xdpf;
+
 		/* Setup next dcb */
 		lan966x_fdma_tx_setup_dcb(tx, next_to_use,
-					  xdpf->len + IFH_LEN_BYTES,
+					  len + IFH_LEN_BYTES,
 					  dma_addr);
 	} else {
 		ifh = page_address(page) + XDP_PACKET_HEADROOM;
@@ -756,25 +770,18 @@ int lan966x_fdma_xmit_xdpf(struct lan966x_port *port,
 		dma_addr = page_pool_get_dma_addr(page);
 		dma_sync_single_for_device(lan966x->dev,
 					   dma_addr + XDP_PACKET_HEADROOM,
-					   xdpf->len + IFH_LEN_BYTES,
+					   len + IFH_LEN_BYTES,
 					   DMA_TO_DEVICE);
 
+		next_dcb_buf->data.page = page;
+
 		/* Setup next dcb */
 		lan966x_fdma_tx_setup_dcb(tx, next_to_use,
-					  xdpf->len + IFH_LEN_BYTES,
+					  len + IFH_LEN_BYTES,
 					  dma_addr + XDP_PACKET_HEADROOM);
 	}
 
-	/* Fill up the buffer */
-	next_dcb_buf = &tx->dcbs_buf[next_to_use];
-	next_dcb_buf->use_skb = false;
-	next_dcb_buf->data.xdpf = xdpf;
-	next_dcb_buf->xdp_ndo = dma_map;
-	next_dcb_buf->len = xdpf->len + IFH_LEN_BYTES;
 	next_dcb_buf->dma_addr = dma_addr;
-	next_dcb_buf->used = true;
-	next_dcb_buf->ptp = false;
-	next_dcb_buf->dev = port->dev;
 
 	/* Start the transmission */
 	lan966x_fdma_tx_start(tx, next_to_use);
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
index 851afb0166b19..59da35a2c93d4 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_main.h
@@ -243,6 +243,7 @@ struct lan966x_tx_dcb_buf {
 	union {
 		struct sk_buff *skb;
 		struct xdp_frame *xdpf;
+		struct page *page;
 	} data;
 	u32 len;
 	u32 used : 1;
@@ -544,6 +545,7 @@ int lan966x_fdma_xmit(struct sk_buff *skb, __be32 *ifh, struct net_device *dev);
 int lan966x_fdma_xmit_xdpf(struct lan966x_port *port,
 			   struct xdp_frame *frame,
 			   struct page *page,
+			   u32 len,
 			   bool dma_map);
 int lan966x_fdma_change_mtu(struct lan966x *lan966x);
 void lan966x_fdma_netdev_init(struct lan966x *lan966x, struct net_device *dev);
diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_xdp.c b/drivers/net/ethernet/microchip/lan966x/lan966x_xdp.c
index 2e6f486ec67d7..a8ad1f4e431cb 100644
--- a/drivers/net/ethernet/microchip/lan966x/lan966x_xdp.c
+++ b/drivers/net/ethernet/microchip/lan966x/lan966x_xdp.c
@@ -62,7 +62,7 @@ int lan966x_xdp_xmit(struct net_device *dev,
 		struct xdp_frame *xdpf = frames[i];
 		int err;
 
-		err = lan966x_fdma_xmit_xdpf(port, xdpf, NULL, true);
+		err = lan966x_fdma_xmit_xdpf(port, xdpf, NULL, xdpf->len, true);
 		if (err)
 			break;
 
@@ -76,7 +76,6 @@ int lan966x_xdp_run(struct lan966x_port *port, struct page *page, u32 data_len)
 {
 	struct bpf_prog *xdp_prog = port->xdp_prog;
 	struct lan966x *lan966x = port->lan966x;
-	struct xdp_frame *xdpf;
 	struct xdp_buff xdp;
 	u32 act;
 
@@ -90,11 +89,9 @@ int lan966x_xdp_run(struct lan966x_port *port, struct page *page, u32 data_len)
 	case XDP_PASS:
 		return FDMA_PASS;
 	case XDP_TX:
-		xdpf = xdp_convert_buff_to_frame(&xdp);
-		if (!xdpf)
-			return FDMA_DROP;
-
-		return lan966x_fdma_xmit_xdpf(port, xdpf, page, false) ?
+		return lan966x_fdma_xmit_xdpf(port, NULL, page,
+					      data_len - IFH_LEN_BYTES,
+					      false) ?
 		       FDMA_DROP : FDMA_TX;
 	case XDP_REDIRECT:
 		if (xdp_do_redirect(port->dev, &xdp, xdp_prog))
-- 
2.38.0