net: remove NETIF_F_NO_CSUM feature bit

Only distinct use is checking if NETIF_F_NOCACHE_COPY should be
enabled by default. The check heuristics is altered a bit here,
so it hits other people than before. The default shouldn't be
trusted for performance-critical cases anyway.

For all other uses NETIF_F_NO_CSUM is equivalent to NETIF_F_HW_CSUM.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 6 insertions, 16 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index f1cca59c4638..26c49d55e79d 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5362,12 +5362,6 @@ static netdev_features_t netdev_fix_features(struct net_device *dev,
                 features &= ~(NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM);
         }
 
-        if ((features & NETIF_F_NO_CSUM) &&
-            (features & (NETIF_F_HW_CSUM|NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM))) {
-                netdev_warn(dev, "mixed no checksumming and other settings.\n");
-                features &= ~(NETIF_F_IP_CSUM|NETIF_F_IPV6_CSUM|NETIF_F_HW_CSUM);
-        }
-
         /* Fix illegal SG+CSUM combinations. */
         if ((features & NETIF_F_SG) &&
             !(features & NETIF_F_ALL_CSUM)) {
@@ -5624,11 +5618,12 @@ int register_netdevice(struct net_device *dev)
         dev->wanted_features = dev->features & dev->hw_features;
 
         /* Turn on no cache copy if HW is doing checksum */
-        dev->hw_features |= NETIF_F_NOCACHE_COPY;
-        if ((dev->features & NETIF_F_ALL_CSUM) &&
-            !(dev->features & NETIF_F_NO_CSUM)) {
-                dev->wanted_features |= NETIF_F_NOCACHE_COPY;
-                dev->features |= NETIF_F_NOCACHE_COPY;
+        if (!(dev->flags & IFF_LOOPBACK)) {
+                dev->hw_features |= NETIF_F_NOCACHE_COPY;
+                if (dev->features & NETIF_F_ALL_CSUM) {
+                        dev->wanted_features |= NETIF_F_NOCACHE_COPY;
+                        dev->features |= NETIF_F_NOCACHE_COPY;
+                }
         }
 
         /* Make NETIF_F_HIGHDMA inheritable to VLAN devices.
@@ -6374,10 +6369,6 @@ netdev_features_t netdev_increment_features(netdev_features_t all,
         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_ALL_CSUM & ~NETIF_F_NO_CSUM))
-                all &= ~NETIF_F_NO_CSUM;
-
         /* If one device supports hw checksumming, set for all. */
         if (all & NETIF_F_GEN_CSUM)
                 all &= ~(NETIF_F_ALL_CSUM & ~NETIF_F_GEN_CSUM);
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index bbf84fe0096e..d2eff9ec88be 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -43,7 +43,6 @@ EXPORT_SYMBOL(ethtool_op_get_link);
 static const char netdev_features_strings[NETDEV_FEATURE_COUNT][ETH_GSTRING_LEN] = {
         [NETIF_F_SG_BIT] =               "tx-scatter-gather",
         [NETIF_F_IP_CSUM_BIT] =          "tx-checksum-ipv4",
-        [NETIF_F_NO_CSUM_BIT] =          "tx-checksum-unneeded",
         [NETIF_F_HW_CSUM_BIT] =          "tx-checksum-ip-generic",
         [NETIF_F_IPV6_CSUM_BIT] =        "tx-checksum-ipv6",
         [NETIF_F_HIGHDMA_BIT] =          "highdma",