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net: enetc: block concurrent XDP transmissions during ring reconfiguration

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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: c33bfaf91c ("net: enetc: set up XDP program under enetc_reconfigure()")
Cc: stable@vger.kernel.org
Signed-off-by: Wei Fang <wei.fang@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20241010092056.298128-3-wei.fang@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Wei Fang 2024-10-10 17:20:54 +08:00 committed by Jakub Kicinski
parent 412950d574
commit c728a95ccf
2 changed files with 15 additions and 0 deletions
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14
drivers/net/ethernet/freescale/enetc/enetc.c
View File

@ -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);

1
drivers/net/ethernet/freescale/enetc/enetc.h
View File

@ -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 */