ixgbevf: Add flag to indicate when rx is in net poll

napi_gro_receive shouldn't be called from netpoll context.  Doing
so was causing kernel panics when jumbo frames larger than 2K were set.
Add a flag to check if the Rx ring processing is occurring from interrupt
context or from netpoll context and call netif_rx() if in the polling
context.

Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/ixgbevf/ixgbevf.h

@@ -229,6 +229,7 @@ struct ixgbevf_adapter {
 	 */
 	u32 flags;
 #define IXGBE_FLAG_IN_WATCHDOG_TASK             (u32)(1)
+#define IXGBE_FLAG_IN_NETPOLL                   (u32)(1 << 1)
 
 	/* OS defined structs */
 	struct net_device *netdev;

drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c

@@ -288,7 +288,10 @@ static void ixgbevf_receive_skb(struct ixgbevf_q_vector *q_vector,
 	if (is_vlan && test_bit(tag & VLAN_VID_MASK, adapter->active_vlans))
 		__vlan_hwaccel_put_tag(skb, tag);
 
-	napi_gro_receive(&q_vector->napi, skb);
+	if (!(adapter->flags & IXGBE_FLAG_IN_NETPOLL))
+		napi_gro_receive(&q_vector->napi, skb);
+	else
+		netif_rx(skb);
 }
 
 /**
@@ -550,9 +553,11 @@ static int ixgbevf_poll(struct napi_struct *napi, int budget)
 	else
 		per_ring_budget = budget;
 
+	adapter->flags |= IXGBE_FLAG_IN_NETPOLL;
 	ixgbevf_for_each_ring(ring, q_vector->rx)
 		clean_complete &= ixgbevf_clean_rx_irq(q_vector, ring,
 						       per_ring_budget);
+	adapter->flags &= ~IXGBE_FLAG_IN_NETPOLL;
 
 	/* If all work not completed, return budget and keep polling */
 	if (!clean_complete)