net-bnx2x: dont reload on GRO change

bnx2x_set_features() forces a driver reload if GRO setting is changed.

A reload makes the ethernet port unresponsive for about 5 seconds.

This is not needed in the common case LRO is enabled, as LRO
(TPA_ENABLE_FLAG) has precedence over GRO (GRO_ENABLE_FLAG)

Tested:
 Verified that "ethtool -K eth0 gro {on|off}" doesn't blackout
 the NIC anymore

Google-Bug-Id: 8440442
Signed-off-by: NEric Dumazet <edumazet@google.com>
Cc: Dmitry Kravkov <dmitry@broadcom.com>
Acked-by: NDmitry Kravkov <dmitry@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c

@@ -4599,6 +4599,7 @@ int bnx2x_set_features(struct net_device *dev, netdev_features_t features)
 {
 	struct bnx2x *bp = netdev_priv(dev);
 	u32 flags = bp->flags;
+	u32 changes;
 	bool bnx2x_reload = false;
 
 	if (features & NETIF_F_LRO)
@@ -4623,10 +4624,16 @@ int bnx2x_set_features(struct net_device *dev, netdev_features_t features)
 		}
 	}
 
-	if (flags ^ bp->flags) {
-		bp->flags = flags;
+	changes = flags ^ bp->flags;
+
+	/* if GRO is changed while LRO is enabled, dont force a reload */
+	if ((changes & GRO_ENABLE_FLAG) && (flags & TPA_ENABLE_FLAG))
+		changes &= ~GRO_ENABLE_FLAG;
+
+	if (changes)
 		bnx2x_reload = true;
-	}
+
+	bp->flags = flags;
 
 	if (bnx2x_reload) {
 		if (bp->recovery_state == BNX2X_RECOVERY_DONE)