linux-kernel - [PATCH 2/2] e1000e: start network tx queue only when link is up

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Message-ID: <155548880068.3454.1621821881762819373.stgit@buzz>
Date:   Wed, 17 Apr 2019 11:13:20 +0300
From:   Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:     netdev@...r.kernel.org, intel-wired-lan@...ts.osuosl.org,
        linux-kernel@...r.kernel.org,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Cc:     Sasha Levin <sashal@...nel.org>, Joseph Yasi <joe.yasi@...il.com>,
        Aaron Brown <aaron.f.brown@...el.com>,
        Alexander Duyck <alexander.duyck@...il.com>,
        e1000-devel@...ts.sourceforge.net
Subject: [PATCH 2/2] e1000e: start network tx queue only when link is up

Driver does not want to keep packets in tx queue when link is lost.
But present code only reset NIC to flush them, but does not prevent
queuing new packets. Moreover reset sequence itself could generate
new packets via netconsole and NIC falls into endless reset loop.

This patch wakes tx queue only when NIC is ready to send packets.

This is proper fix for problem addressed by commit 0f9e980bf5ee
("e1000e: fix cyclic resets at link up with active tx").

Signed-off-by: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
Suggested-by: Alexander Duyck <alexander.duyck@...il.com>
---
 drivers/net/ethernet/intel/e1000e/netdev.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index ba96e52aa8d1..fe643d66aa10 100644
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -4209,7 +4209,7 @@ void e1000e_up(struct e1000_adapter *adapter)
 		e1000_configure_msix(adapter);
 	e1000_irq_enable(adapter);
 
-	netif_start_queue(adapter->netdev);
+	/* tx queue started by watchdog timer when link is up */
 
 	e1000e_trigger_lsc(adapter);
 }
@@ -4607,6 +4607,7 @@ int e1000e_open(struct net_device *netdev)
 	pm_runtime_get_sync(&pdev->dev);
 
 	netif_carrier_off(netdev);
+	netif_stop_queue(netdev);
 
 	/* allocate transmit descriptors */
 	err = e1000e_setup_tx_resources(adapter->tx_ring);
@@ -4667,7 +4668,6 @@ int e1000e_open(struct net_device *netdev)
 	e1000_irq_enable(adapter);
 
 	adapter->tx_hang_recheck = false;
-	netif_start_queue(netdev);
 
 	hw->mac.get_link_status = true;
 	pm_runtime_put(&pdev->dev);
@@ -5289,6 +5289,7 @@ static void e1000_watchdog_task(struct work_struct *work)
 			if (phy->ops.cfg_on_link_up)
 				phy->ops.cfg_on_link_up(hw);
 
+			netif_wake_queue(netdev);
 			netif_carrier_on(netdev);
 
 			if (!test_bit(__E1000_DOWN, &adapter->state))
@@ -5302,6 +5303,7 @@ static void e1000_watchdog_task(struct work_struct *work)
 			/* Link status message must follow this format */
 			pr_info("%s NIC Link is Down\n", adapter->netdev->name);
 			netif_carrier_off(netdev);
+			netif_stop_queue(netdev);
 			if (!test_bit(__E1000_DOWN, &adapter->state))
 				mod_timer(&adapter->phy_info_timer,
 					  round_jiffies(jiffies + 2 * HZ));