Subject: [PATCH AUTOSEL 5.1 042/219] Revert "e1000e: fix cyclic resets at link up with active tx"

From: Sasha Levin <[email-masked]>
Date: Mon, 15 Jul 2019 10:00:43 -0400

From: Konstantin Khlebnikov <[email-masked]>

[ Upstream commit caff422ea81e144842bc44bab408d85ac449377b ]

This reverts commit 0f9e980bf5ee1a97e2e401c846b2af989eb21c61.

That change cased false-positive warning about hardware hang:

e1000e: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx
IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
e1000e 0000:00:1f.6 eth0: Detected Hardware Unit Hang:
   TDH                  <0>
   TDT                  <1>
   next_to_use          <1>
   next_to_clean        <0>
buffer_info[next_to_clean]:
   time_stamp           <fffba7a7>
   next_to_watch        <0>
   jiffies              <fffbb140>
   next_to_watch.status <0>
MAC Status             <40080080>
PHY Status             <7949>
PHY 1000BASE-T Status  <0>
PHY Extended Status    <3000>
PCI Status             <10>
e1000e: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: Rx/Tx

Besides warning everything works fine.
Original issue will be fixed property in following patch.

Signed-off-by: Konstantin Khlebnikov <[email-masked]>
Reported-by: Joseph Yasi <[email-masked]>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=203175
Tested-by: Joseph Yasi <[email-masked]>
Tested-by: Aaron Brown <[email-masked]>
Tested-by: Oleksandr Natalenko <[email-masked]>
Signed-off-by: Jeff Kirsher <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
---
 drivers/net/ethernet/intel/e1000e/netdev.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index c10c9d7eadaa..6230b4bb1699 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -5309,13 +5309,8 @@ static void e1000_watchdog_task(struct work_struct *work)
 			/* 8000ES2LAN requires a Rx packet buffer work-around
 			 * on link down event; reset the controller to flush
 			 * the Rx packet buffer.
-			 *
-			 * If the link is lost the controller stops DMA, but
-			 * if there is queued Tx work it cannot be done.  So
-			 * reset the controller to flush the Tx packet buffers.
 			 */
-			if ((adapter->flags & FLAG_RX_NEEDS_RESTART) ||
-			    e1000_desc_unused(tx_ring) + 1 < tx_ring->count)
+			if (adapter->flags & FLAG_RX_NEEDS_RESTART)
 				adapter->flags |= FLAG_RESTART_NOW;
 			else
 				pm_schedule_suspend(netdev->dev.parent,
@@ -5338,6 +5333,14 @@ static void e1000_watchdog_task(struct work_struct *work)
 	adapter->gotc_old = adapter->stats.gotc;
 	spin_unlock(&adapter->stats64_lock);
 
+	/* If the link is lost the controller stops DMA, but
+	 * if there is queued Tx work it cannot be done.  So
+	 * reset the controller to flush the Tx packet buffers.
+	 */
+	if (!netif_carrier_ok(netdev) &&
+	    (e1000_desc_unused(tx_ring) + 1 < tx_ring->count))
+		adapter->flags |= FLAG_RESTART_NOW;
+
 	/* If reset is necessary, do it outside of interrupt context. */
 	if (adapter->flags & FLAG_RESTART_NOW) {
 		schedule_work(&adapter->reset_task);
-- 
2.20.1