igc: Add ndo_tx_timeout support

On some platforms, 100/1000/2500 speeds seem to have sometimes problems
reporting false positive tx unit hang during stressful UDP traffic. Likely
other Intel drivers introduce responses to a tx hang. Update the 'tx hang'
comparator with the comparison of the head and tail of ring pointers and
restore the tx_timeout_factor to the previous value (one).

This can be test by using netperf or iperf3 applications.
Example:
iperf3 -s -p 5001
iperf3 -c 192.168.0.2 --udp -p 5001 --time 600 -b 0

netserver -p 16604
netperf -H 192.168.0.2 -l 600 -p 16604 -t UDP_STREAM -- -m 64000

Fixes: b27b8dc ("igc: Increase timeout value for Speed 100/1000/2500")
Signed-off-by: Sasha Neftin <[email protected]>
Tested-by: Naama Meir <[email protected]>
Signed-off-by: Tony Nguyen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: aneftin

drivers/net/ethernet/intel/igc/igc_main.c

@@ -2942,7 +2942,9 @@ static bool igc_clean_tx_irq(struct igc_q_vector *q_vector, int napi_budget)
 		if (tx_buffer->next_to_watch &&
 		    time_after(jiffies, tx_buffer->time_stamp +
 		    (adapter->tx_timeout_factor * HZ)) &&
-		    !(rd32(IGC_STATUS) & IGC_STATUS_TXOFF)) {
+		    !(rd32(IGC_STATUS) & IGC_STATUS_TXOFF) &&
+		    (rd32(IGC_TDH(tx_ring->reg_idx)) !=
+		     readl(tx_ring->tail))) {
 			/* detected Tx unit hang */
 			netdev_err(tx_ring->netdev,
 				   "Detected Tx Unit Hang\n"
@@ -5068,6 +5070,24 @@ static int igc_change_mtu(struct net_device *netdev, int new_mtu)
 	return 0;
 }
 
+/**
+ * igc_tx_timeout - Respond to a Tx Hang
+ * @netdev: network interface device structure
+ * @txqueue: queue number that timed out
+ **/
+static void igc_tx_timeout(struct net_device *netdev,
+			   unsigned int __always_unused txqueue)
+{
+	struct igc_adapter *adapter = netdev_priv(netdev);
+	struct igc_hw *hw = &adapter->hw;
+
+	/* Do the reset outside of interrupt context */
+	adapter->tx_timeout_count++;
+	schedule_work(&adapter->reset_task);
+	wr32(IGC_EICS,
+	     (adapter->eims_enable_mask & ~adapter->eims_other));
+}
+
 /**
  * igc_get_stats64 - Get System Network Statistics
  * @netdev: network interface device structure
@@ -5495,7 +5515,7 @@ static void igc_watchdog_task(struct work_struct *work)
 			case SPEED_100:
 			case SPEED_1000:
 			case SPEED_2500:
-				adapter->tx_timeout_factor = 7;
+				adapter->tx_timeout_factor = 1;
 				break;
 			}
 
@@ -6320,6 +6340,7 @@ static const struct net_device_ops igc_netdev_ops = {
 	.ndo_set_rx_mode	= igc_set_rx_mode,
 	.ndo_set_mac_address	= igc_set_mac,
 	.ndo_change_mtu		= igc_change_mtu,
+	.ndo_tx_timeout		= igc_tx_timeout,
 	.ndo_get_stats64	= igc_get_stats64,
 	.ndo_fix_features	= igc_fix_features,
 	.ndo_set_features	= igc_set_features,