netdev - [PATCH net 1/1] ionic: wait on queue start until after IFF

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Date:   Mon,  8 Jun 2020 20:41:43 -0700
From:   Shannon Nelson <snelson@...sando.io>
To:     netdev@...r.kernel.org, davem@...emloft.net
Cc:     Shannon Nelson <snelson@...sando.io>
Subject: [PATCH net 1/1] ionic: wait on queue start until after IFF_UP

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>
---
 drivers/net/ethernet/pensando/ionic/ionic_lif.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/pensando/ionic/ionic_lif.c b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
index 7321a92f8395..fbc36e9e4729 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_lif.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_lif.c
@@ -116,7 +116,7 @@ static void ionic_link_status_check(struct ionic_lif *lif)
 			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)) {
@@ -124,7 +124,7 @@ static void ionic_link_status_check(struct ionic_lif *lif)
 			netif_carrier_off(netdev);
 		}

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

-- 
2.17.1