When testing the XDP_REDIRECT function on the LS1028A platform, we found a very reproducible issue that the Tx frames can no longer be sent out even if XDP_REDIRECT is turned off. Specifically, if there is a lot of traffic on Rx direction, when XDP_REDIRECT is turned on, the console may display some warnings like "timeout for tx ring #6 clear", and all redirected frames will be dropped, the detailed log is as follows.
root@ls1028ardb:~# ./xdp-bench redirect eno0 eno2 Redirecting from eno0 (ifindex 3; driver fsl_enetc) to eno2 (ifindex 4; driver fsl_enetc) [203.849809] fsl_enetc 0000:00:00.2 eno2: timeout for tx ring #5 clear [204.006051] fsl_enetc 0000:00:00.2 eno2: timeout for tx ring #6 clear [204.161944] fsl_enetc 0000:00:00.2 eno2: timeout for tx ring #7 clear eno0->eno2 1420505 rx/s 1420590 err,drop/s 0 xmit/s xmit eno0->eno2 0 xmit/s 1420590 drop/s 0 drv_err/s 15.71 bulk-avg eno0->eno2 1420484 rx/s 1420485 err,drop/s 0 xmit/s xmit eno0->eno2 0 xmit/s 1420485 drop/s 0 drv_err/s 15.71 bulk-avg
By analyzing the XDP_REDIRECT implementation of enetc driver, the driver will reconfigure Tx and Rx BD rings when a bpf program is installed or uninstalled, but there is no mechanisms to block the redirected frames when enetc driver reconfigures rings. Similarly, XDP_TX verdicts on received frames can also lead to frames being enqueued in the Tx rings. Because XDP ignores the state set by the netif_tx_wake_queue() API, so introduce the ENETC_TX_DOWN flag to suppress transmission of XDP frames.
Fixes: c33bfaf91c4c ("net: enetc: set up XDP program under enetc_reconfigure()") Cc: stable@vger.kernel.org Signed-off-by: Wei Fang wei.fang@nxp.com --- v2 changes: Remove a blank line from the end of enetc_disable_tx_bdrs(). v3 changes: Block the XDP_TX frames when ENETC_TX_DOWN flag is set. v4 changes: 1. Modify the title and rephrase the commit message. 2. Move the changes of operation order in enect_stop() and enetc_stop() to a separated patch (patch 3). --- drivers/net/ethernet/freescale/enetc/enetc.c | 14 ++++++++++++++ drivers/net/ethernet/freescale/enetc/enetc.h | 1 + 2 files changed, 15 insertions(+)
diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c index 56e59721ec7d..482c44ed9d46 100644 --- a/drivers/net/ethernet/freescale/enetc/enetc.c +++ b/drivers/net/ethernet/freescale/enetc/enetc.c @@ -902,6 +902,7 @@ static bool enetc_clean_tx_ring(struct enetc_bdr *tx_ring, int napi_budget)
if (unlikely(tx_frm_cnt && netif_carrier_ok(ndev) && __netif_subqueue_stopped(ndev, tx_ring->index) && + !test_bit(ENETC_TX_DOWN, &priv->flags) && (enetc_bd_unused(tx_ring) >= ENETC_TXBDS_MAX_NEEDED))) { netif_wake_subqueue(ndev, tx_ring->index); } @@ -1377,6 +1378,9 @@ int enetc_xdp_xmit(struct net_device *ndev, int num_frames, int xdp_tx_bd_cnt, i, k; int xdp_tx_frm_cnt = 0;
+ if (unlikely(test_bit(ENETC_TX_DOWN, &priv->flags))) + return -ENETDOWN; + enetc_lock_mdio();
tx_ring = priv->xdp_tx_ring[smp_processor_id()]; @@ -1602,6 +1606,12 @@ static int enetc_clean_rx_ring_xdp(struct enetc_bdr *rx_ring, break; case XDP_TX: tx_ring = priv->xdp_tx_ring[rx_ring->index]; + if (unlikely(test_bit(ENETC_TX_DOWN, &priv->flags))) { + enetc_xdp_drop(rx_ring, orig_i, i); + tx_ring->stats.xdp_tx_drops++; + break; + } + xdp_tx_bd_cnt = enetc_rx_swbd_to_xdp_tx_swbd(xdp_tx_arr, rx_ring, orig_i, i); @@ -2463,6 +2473,8 @@ void enetc_start(struct net_device *ndev) enetc_enable_bdrs(priv);
netif_tx_start_all_queues(ndev); + + clear_bit(ENETC_TX_DOWN, &priv->flags); } EXPORT_SYMBOL_GPL(enetc_start);
@@ -2520,6 +2532,8 @@ void enetc_stop(struct net_device *ndev) struct enetc_ndev_priv *priv = netdev_priv(ndev); int i;
+ set_bit(ENETC_TX_DOWN, &priv->flags); + netif_tx_stop_all_queues(ndev);
enetc_disable_bdrs(priv); diff --git a/drivers/net/ethernet/freescale/enetc/enetc.h b/drivers/net/ethernet/freescale/enetc/enetc.h index 97524dfa234c..fb7d98d57783 100644 --- a/drivers/net/ethernet/freescale/enetc/enetc.h +++ b/drivers/net/ethernet/freescale/enetc/enetc.h @@ -325,6 +325,7 @@ enum enetc_active_offloads {
enum enetc_flags_bit { ENETC_TX_ONESTEP_TSTAMP_IN_PROGRESS = 0, + ENETC_TX_DOWN, };
/* interrupt coalescing modes */