[PATCH net-next v2 8/8] net: xilinx: tsn: deliver endpoint RX frames to DSA user ports
From: Srinivas Neeli <srinivas.neeli@amd.com>
Date: 2026-09-08 19:21:01
Also in:
linux-arm-kernel, linux-devicetree, linux-rt-devel, lkml
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Nagadheeraj Rottela <redacted> The DSA core routes an RX frame to a user port from the port metadata attached to the skb. Without that metadata, frames from the two MACs cannot reach their swpN netdevs. Allocate a METADATA_HW_PORT_MUX entry per MAC port at probe and attach the matching entry to each RX frame by its TUSER port_id. Frames from MAC1 and MAC2 now reach the correct user netdev, which completes the conduit data path. The RX callback runs in softirq and hands the frame to __netif_rx(), which queues it on the backlog instead of consuming it inline, so the attached dst must be a counted reference (dst_hold() + skb_dst_set()) to survive the handoff. Signed-off-by: Nagadheeraj Rottela <redacted> Co-developed-by: Srinivas Neeli <srinivas.neeli@amd.com> Signed-off-by: Srinivas Neeli <srinivas.neeli@amd.com> --- Changes in v2: - Attach the RX port metadata only when the netdev is a DSA conduit (netdev_uses_dsa()), so no dev-less dst leaks into the stack when no switch is bound. - Take a real reference on the per-port metadata_dst with dst_hold() + skb_dst_set() before the __netif_rx() backlog handoff, instead of skb_dst_set_noref() + skb_dst_force(). The entries stay live for the driver lifetime, so this drops the rcu_read_lock() that skb_dst_force() would need in the softirq callback. - Release the per-port metadata_dst with dst_release() at teardown, not metadata_dst_free(), so an skb still referencing it is not freed early. --- drivers/net/ethernet/xilinx/tsn/xilinx_tsn_ep.c | 55 ++++++++++++++++++++++++- 1 file changed, 54 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/xilinx/tsn/xilinx_tsn_ep.c b/drivers/net/ethernet/xilinx/tsn/xilinx_tsn_ep.c
index 9e9a45169681..db7da26521d0 100644
--- a/drivers/net/ethernet/xilinx/tsn/xilinx_tsn_ep.c
+++ b/drivers/net/ethernet/xilinx/tsn/xilinx_tsn_ep.c@@ -29,6 +29,8 @@ #include <linux/timer.h> #include <linux/types.h> +#include <net/dsa.h> +#include <net/dst_metadata.h> #include <net/netdev_queues.h> #include "xilinx_tsn.h"
@@ -58,6 +60,9 @@ #define TSN_TUSER_PORT_MAC1 0x1 #define TSN_TUSER_PORT_MAC2 0x2 +/* Sized to index port_md[] by TUSER port_id (1 or 2, slot 0 unused) */ +#define XLNX_TSN_EP_PORT_MD_SLOTS (TSN_TUSER_PORT_MAC2 + 1) + /** * struct skbuf_dma_descriptor - skb container for each in-flight DMA descriptor * @sgl: scatter-gather list backing the DMA mapping
@@ -114,6 +119,8 @@ struct xlnx_tsn_ep_dma_chan { * @tx_chans: array of TX channels (size @num_tx_queues) * @rx_chans: array of RX channels (size @num_rx_queues) * @closing: set in ndo_stop so the RX completion callback stops re-arming + * @port_md: per-TUSER-port METADATA_HW_PORT_MUX entries attached on RX, + * indexed by port_id (1 for MAC1, 2 for MAC2) */ struct xlnx_tsn_ep { struct net_device *ndev;
@@ -128,6 +135,8 @@ struct xlnx_tsn_ep { struct xlnx_tsn_ep_dma_chan **rx_chans; bool closing; + + struct metadata_dst *port_md[XLNX_TSN_EP_PORT_MD_SLOTS]; }; static inline struct skbuf_dma_descriptor *
@@ -292,6 +301,10 @@ static void ep_dma_rx_cb(void *data, const struct dmaengine_result *result) } skb_put(skb, rx_len); + if (netdev_uses_dsa(ndev)) { + dst_hold(&ep->port_md[port_id]->dst); + skb_dst_set(skb, &ep->port_md[port_id]->dst); + } skb->dev = ndev; skb->protocol = eth_type_trans(skb, ndev); skb->ip_summed = CHECKSUM_NONE;
@@ -854,6 +867,37 @@ static int ep_count_dma_queues(struct device *dev, u32 *out_tx, u32 *out_rx, return 0; } +static void ep_free_port_md(struct xlnx_tsn_ep *ep) +{ + int i; + + for (i = 0; i < XLNX_TSN_EP_PORT_MD_SLOTS; i++) { + if (ep->port_md[i]) { + dst_release(&ep->port_md[i]->dst); + ep->port_md[i] = NULL; + } + } +} + +static int ep_alloc_port_md(struct xlnx_tsn_ep *ep) +{ + int i; + + for (i = TSN_TUSER_PORT_MAC1; i <= TSN_TUSER_PORT_MAC2; i++) { + struct metadata_dst *md; + + md = metadata_dst_alloc(0, METADATA_HW_PORT_MUX, GFP_KERNEL); + if (!md) { + ep_free_port_md(ep); + return -ENOMEM; + } + md->u.port_info.port_id = i; + ep->port_md[i] = md; + } + + return 0; +} + static int xlnx_tsn_ep_probe(struct platform_device *pdev) { u32 rx_chan_num[TSN_MAX_RX_QUEUE];
@@ -939,16 +983,24 @@ static int xlnx_tsn_ep_probe(struct platform_device *pdev) ndev->dev_addr); } + ret = ep_alloc_port_md(ep); + if (ret) { + dev_err_probe(dev, ret, "failed to allocate per-port metadata\n"); + goto err_free_ndev; + } + platform_set_drvdata(pdev, ep); ret = register_netdev(ndev); if (ret) { dev_err_probe(dev, ret, "failed to register net device\n"); - goto err_free_ndev; + goto err_free_md; } return 0; +err_free_md: + ep_free_port_md(ep); err_free_ndev: free_netdev(ndev); return ret;
@@ -962,6 +1014,7 @@ static void xlnx_tsn_ep_remove(struct platform_device *pdev) return; unregister_netdev(ep->ndev); + ep_free_port_md(ep); free_netdev(ep->ndev); }
--
2.43.0