net: fix netdev_increment_features()

Simplify and fix netdev_increment_features() to conform to what is
stated in netdevice.h comments about NETIF_F_ONE_FOR_ALL.
Include FCoE segmentation and VLAN-challedged flags in computation.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index 3bbb4c2..7db99b5 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6164,33 +6164,20 @@
  */
 u32 netdev_increment_features(u32 all, u32 one, u32 mask)
 {
+	if (mask & NETIF_F_GEN_CSUM)
+		mask |= NETIF_F_ALL_CSUM;
+	mask |= NETIF_F_VLAN_CHALLENGED;
+
+	all |= one & (NETIF_F_ONE_FOR_ALL|NETIF_F_ALL_CSUM) & mask;
+	all &= one | ~NETIF_F_ALL_FOR_ALL;
+
 	/* If device needs checksumming, downgrade to it. */
-	if (all & NETIF_F_NO_CSUM && !(one & NETIF_F_NO_CSUM))
-		all ^= NETIF_F_NO_CSUM | (one & NETIF_F_ALL_CSUM);
-	else if (mask & NETIF_F_ALL_CSUM) {
-		/* If one device supports v4/v6 checksumming, set for all. */
-		if (one & (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM) &&
-		    !(all & NETIF_F_GEN_CSUM)) {
-			all &= ~NETIF_F_ALL_CSUM;
-			all |= one & (NETIF_F_IP_CSUM | NETIF_F_IPV6_CSUM);
-		}
+	if (all & (NETIF_F_ALL_CSUM & ~NETIF_F_NO_CSUM))
+		all &= ~NETIF_F_NO_CSUM;
 
-		/* If one device supports hw checksumming, set for all. */
-		if (one & NETIF_F_GEN_CSUM && !(all & NETIF_F_GEN_CSUM)) {
-			all &= ~NETIF_F_ALL_CSUM;
-			all |= NETIF_F_HW_CSUM;
-		}
-	}
-
-	/* If device can't no cache copy, don't do for all */
-	if (!(one & NETIF_F_NOCACHE_COPY))
-		all &= ~NETIF_F_NOCACHE_COPY;
-
-	one |= NETIF_F_ALL_CSUM;
-
-	one |= all & NETIF_F_ONE_FOR_ALL;
-	all &= one | NETIF_F_LLTX | NETIF_F_GSO | NETIF_F_UFO;
-	all |= one & mask & NETIF_F_ONE_FOR_ALL;
+	/* If one device supports hw checksumming, set for all. */
+	if (all & NETIF_F_GEN_CSUM)
+		all &= ~(NETIF_F_ALL_CSUM & ~NETIF_F_GEN_CSUM);
 
 	return all;
 }