net: add busy_poll device feature

Currently there is no way how to find out if a device supports busy
polling. So add a feature and make it dependent on ndo_busy_poll
existence.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 8 insertions, 0 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index 757063420ce0..75e88e0372cb 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5696,6 +5696,13 @@ static netdev_features_t netdev_fix_features(struct net_device *dev,
                 }
         }
 
+#ifdef CONFIG_NET_RX_BUSY_POLL
+        if (dev->netdev_ops->ndo_busy_poll)
+                features |= NETIF_F_BUSY_POLL;
+        else
+#endif
+                features &= ~NETIF_F_BUSY_POLL;
+
         return features;
 }
 
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 30071dec287a..640ba0e5831c 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -97,6 +97,7 @@ static const char netdev_features_strings[NETDEV_FEATURE_COUNT][ETH_GSTRING_LEN]
         [NETIF_F_RXFCS_BIT] =            "rx-fcs",
         [NETIF_F_RXALL_BIT] =            "rx-all",
         [NETIF_F_HW_L2FW_DOFFLOAD_BIT] = "l2-fwd-offload",
+        [NETIF_F_BUSY_POLL_BIT] =        "busy-poll",
 };
 
 static int ethtool_get_features(struct net_device *dev, void __user *useraddr)