linux-kernel - [PATCH 5.7 109/163] ionic: wait on queue start until after IFF

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Date:   Tue, 16 Jun 2020 17:34:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Shannon Nelson <snelson@...sando.io>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.7 109/163] ionic: wait on queue start until after IFF_UP

From: Shannon Nelson <snelson@...sando.io>

[ Upstream commit 976ee3b21119dcf5c6d96233d688a1453f29fa83 ]

The netif_running() test looks at __LINK_STATE_START which
gets set before ndo_open() is called, there is a window of
time between that and when the queues are actually ready to
be run.  If ionic_check_link_status() notices that the link is
up very soon after netif_running() becomes true, it might try
to run the queues before they are ready, causing all manner of
potential issues.  Since the netdev->flags IFF_UP isn't set
until after ndo_open() returns, we can wait for that before
we allow ionic_check_link_status() to start the queues.

On the way back to close, __LINK_STATE_START is cleared before
calling ndo_stop(), and IFF_UP is cleared after.  Both of
these need to be true in order to safely stop the queues
from ionic_check_link_status().

Fixes: 49d3b493673a ("ionic: disable the queues on link down")
Signed-off-by: Shannon Nelson <snelson@...sando.io>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/ethernet/pensando/ionic/ionic_lif.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/pensando/ionic/ionic_lif.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
@@ -105,7 +105,7 @@ static void ionic_link_status_check(stru
 			netif_carrier_on(netdev);
 		}

-		if (netif_running(lif->netdev))
+		if (lif->netdev->flags & IFF_UP && netif_running(lif->netdev))
 			ionic_start_queues(lif);
 	} else {
 		if (netif_carrier_ok(netdev)) {
@@ -113,7 +113,7 @@ static void ionic_link_status_check(stru
 			netif_carrier_off(netdev);
 		}

-		if (netif_running(lif->netdev))
+		if (lif->netdev->flags & IFF_UP && netif_running(lif->netdev))
 			ionic_stop_queues(lif);
 	}