net: ena: fix continuous keep-alive resets

last_keep_alive_jiffies is updated in probe and when a keep-alive
event is received.  In case the driver times-out on a keep-alive event,
it has high chances of continuously timing-out on keep-alive events.
This is because when the driver recovers from the keep-alive-timeout reset
the value of last_keep_alive_jiffies is very old, and if a keep-alive
event is not received before the next timer expires, the value of
last_keep_alive_jiffies will cause another keep-alive-timeout reset
and so forth in a loop.

Solution:
Update last_keep_alive_jiffies whenever the device is restored after
reset.

Fixes: 1738cd3e ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: Noam Dagan <ndagan@amazon.com>
Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/amazon/ena/ena_netdev.c

@@ -3486,6 +3486,7 @@ static int ena_restore_device(struct ena_adapter *adapter)
 		netif_carrier_on(adapter->netdev);
 
 	mod_timer(&adapter->timer_service, round_jiffies(jiffies + HZ));
+	adapter->last_keep_alive_jiffies = jiffies;
 	dev_err(&pdev->dev,
 		"Device reset completed successfully, Driver info: %s\n",
 		version);