From ce3192e0dafa829e76edefecc16a32589b53c875 Mon Sep 17 00:00:00 2001 From: Daniel Machon Date: Mon, 26 Oct 2026 14:46:39 +0100 Subject: [PATCH] net: lan966x: fix the DB dataptr of frames from ndo_xdp_xmit lan966x_fdma_xmit_xdpf() transmits both XDP_TX frames and xdp_frames from ndo_xdp_xmit, and builds the DB with lan966x_fdma_xdp_tx_dataptr_cb(), which adds XDP_PACKET_HEADROOM to the stored DMA address. Before this patch, the headroom is also added for xdp_frames. For XDP_TX the stored address is the start of the page pool page, but for an xdp_frame it is the mapping of the IFH placed in front of the frame data, so frames from ndo_xdp_xmit are read from XDP_PACKET_HEADROOM bytes after their IFH. Use the plain tx dataptr callback for xdp_frames. Found by an AI code review agent. Reproduced on a lan9668 board with an XDP program redirecting frames from one port to another: none of the 20 frames arrived intact on the link partner. With the fix all 20 did. Fixes: 29cc3a66a81d ("net: lan966x: use FDMA library for adding DCB's in the tx path") Signed-off-by: Daniel Machon Link: https://patch.msgid.link/20261026-lan966x-xdp-xmit-dataptr-v1-1-d0dd068324de@microchip.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c index a7940eca5df3..8ea86b800af7 100644 --- a/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c +++ b/drivers/net/ethernet/microchip/lan966x/lan966x_fdma.c @@ -686,7 +686,8 @@ int lan966x_fdma_xmit_xdpf(struct lan966x_port *port, void *ptr, u32 len) FDMA_DCB_STATUS_BLOCKO(0) | FDMA_DCB_STATUS_BLOCKL(next_dcb_buf->len), &fdma_nextptr_cb, - &lan966x_fdma_xdp_tx_dataptr_cb); + len ? &lan966x_fdma_xdp_tx_dataptr_cb : + &lan966x_fdma_tx_dataptr_cb); /* Start the transmission */ lan966x_fdma_tx_start(tx);