The Tx BD rings are disabled first in enetc_stop() and the driver waits for them to become empty. This operation is not safe while the ring is actively transmitting frames, and will cause the ring to not be empty and hardware exception. As described in the NETC block guide, software should only disable an active Tx ring after all pending ring entries have been consumed (i.e. when PI = CI). Disabling a transmit ring that is actively processing BDs risks a HW-SW race hazard whereby a hardware resource becomes assigned to work on one or more ring entries only to have those entries be removed due to the ring becoming disabled.
When testing XDP_REDIRECT feautre, although all frames were blocked from being put into Tx rings during ring reconfiguration, the similar warning log was still encountered:
fsl_enetc 0000:00:00.2 eno2: timeout for tx ring #6 clear fsl_enetc 0000:00:00.2 eno2: timeout for tx ring #7 clear
The reason is that when there are still unsent frames in the Tx ring, disabling the Tx ring causes the remaining frames to be unable to be sent out. And the Tx ring cannot be restored, which means that even if the xdp program is uninstalled, the Tx frames cannot be sent out anymore. Therefore, correct the operation order in enect_start() and enect_stop().
Fixes: ff58fda09096 ("net: enetc: prioritize ability to go down over packet processing") Cc: stable@vger.kernel.org Signed-off-by: Wei Fang wei.fang@nxp.com --- v4 changes: new patch --- drivers/net/ethernet/freescale/enetc/enetc.c | 36 ++++++++++++++------ 1 file changed, 26 insertions(+), 10 deletions(-)
diff --git a/drivers/net/ethernet/freescale/enetc/enetc.c b/drivers/net/ethernet/freescale/enetc/enetc.c index 482c44ed9d46..52da10f62430 100644 --- a/drivers/net/ethernet/freescale/enetc/enetc.c +++ b/drivers/net/ethernet/freescale/enetc/enetc.c @@ -2233,18 +2233,24 @@ static void enetc_enable_rxbdr(struct enetc_hw *hw, struct enetc_bdr *rx_ring) enetc_rxbdr_wr(hw, idx, ENETC_RBMR, rbmr); }
-static void enetc_enable_bdrs(struct enetc_ndev_priv *priv) +static void enetc_enable_rx_bdrs(struct enetc_ndev_priv *priv) { struct enetc_hw *hw = &priv->si->hw; int i;
- for (i = 0; i < priv->num_tx_rings; i++) - enetc_enable_txbdr(hw, priv->tx_ring[i]); - for (i = 0; i < priv->num_rx_rings; i++) enetc_enable_rxbdr(hw, priv->rx_ring[i]); }
+static void enetc_enable_tx_bdrs(struct enetc_ndev_priv *priv) +{ + struct enetc_hw *hw = &priv->si->hw; + int i; + + for (i = 0; i < priv->num_tx_rings; i++) + enetc_enable_txbdr(hw, priv->tx_ring[i]); +} + static void enetc_disable_rxbdr(struct enetc_hw *hw, struct enetc_bdr *rx_ring) { int idx = rx_ring->index; @@ -2261,18 +2267,24 @@ static void enetc_disable_txbdr(struct enetc_hw *hw, struct enetc_bdr *rx_ring) enetc_txbdr_wr(hw, idx, ENETC_TBMR, 0); }
-static void enetc_disable_bdrs(struct enetc_ndev_priv *priv) +static void enetc_disable_rx_bdrs(struct enetc_ndev_priv *priv) { struct enetc_hw *hw = &priv->si->hw; int i;
- for (i = 0; i < priv->num_tx_rings; i++) - enetc_disable_txbdr(hw, priv->tx_ring[i]); - for (i = 0; i < priv->num_rx_rings; i++) enetc_disable_rxbdr(hw, priv->rx_ring[i]); }
+static void enetc_disable_tx_bdrs(struct enetc_ndev_priv *priv) +{ + struct enetc_hw *hw = &priv->si->hw; + int i; + + for (i = 0; i < priv->num_tx_rings; i++) + enetc_disable_txbdr(hw, priv->tx_ring[i]); +} + static void enetc_wait_txbdr(struct enetc_hw *hw, struct enetc_bdr *tx_ring) { int delay = 8, timeout = 100; @@ -2462,6 +2474,8 @@ void enetc_start(struct net_device *ndev)
enetc_setup_interrupts(priv);
+ enetc_enable_tx_bdrs(priv); + for (i = 0; i < priv->bdr_int_num; i++) { int irq = pci_irq_vector(priv->si->pdev, ENETC_BDR_INT_BASE_IDX + i); @@ -2470,7 +2484,7 @@ void enetc_start(struct net_device *ndev) enable_irq(irq); }
- enetc_enable_bdrs(priv); + enetc_enable_rx_bdrs(priv);
netif_tx_start_all_queues(ndev);
@@ -2536,7 +2550,7 @@ void enetc_stop(struct net_device *ndev)
netif_tx_stop_all_queues(ndev);
- enetc_disable_bdrs(priv); + enetc_disable_rx_bdrs(priv);
for (i = 0; i < priv->bdr_int_num; i++) { int irq = pci_irq_vector(priv->si->pdev, @@ -2549,6 +2563,8 @@ void enetc_stop(struct net_device *ndev)
enetc_wait_bdrs(priv);
+ enetc_disable_tx_bdrs(priv); + enetc_clear_interrupts(priv); } EXPORT_SYMBOL_GPL(enetc_stop);