Merge branch 'net-NETIF_F_GRO_HW'

Michael Chan says:

====================
Introduce NETIF_F_GRO_HW

Introduce NETIF_F_GRO_HW feature flag and convert drivers that support
hardware GRO to use the new flag.

v5:
- Documentation changes requested by Alexander Duyck.
- bnx2x changes requested by Manish Chopra to enable LRO by default, and
disable GRO_HW if disable_tpa module parameter is set.

v4:
- more changes requested by Alexander Duyck:
- check GRO_HW/GRO dependency in drivers's ndo_fix_features().
- Reverse the order of RXCSUM and GRO_HW dependency check in
netdev_fix_features().
- No propagation in netdev_disable_gro_hw().

v3:
- Let driver's ndo_fix_features() disable NETIF_F_LRO when NETIF_F_GRO_HW
is set instead of doing it in common netdev_fix_features().

v2:
- NETIF_F_GRO_HW flag propagation between upper and lower devices not
required (see patch 1).
- NETIF_F_GRO_HW depends on NETIF_F_GRO and NETIF_F_RXCSUM.
- Add dev_disable_gro_hw() to disable GRO_HW for generic XDP.
- Use ndo_fix_features() on all 3 drivers to drop GRO_HW when it is not
supported
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 30 insertions, 0 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index b0eee49a2489..c7db39926769 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1542,6 +1542,23 @@ void dev_disable_lro(struct net_device *dev)
 }
 EXPORT_SYMBOL(dev_disable_lro);
 
+/**
+ *	dev_disable_gro_hw - disable HW Generic Receive Offload on a device
+ *	@dev: device
+ *
+ *	Disable HW Generic Receive Offload (GRO_HW) on a net device.  Must be
+ *	called under RTNL.  This is needed if Generic XDP is installed on
+ *	the device.
+ */
+static void dev_disable_gro_hw(struct net_device *dev)
+{
+	dev->wanted_features &= ~NETIF_F_GRO_HW;
+	netdev_update_features(dev);
+
+	if (unlikely(dev->features & NETIF_F_GRO_HW))
+		netdev_WARN(dev, "failed to disable GRO_HW!\n");
+}
+
 static int call_netdevice_notifier(struct notifier_block *nb, unsigned long val,
 				   struct net_device *dev)
 {
@@ -4564,6 +4581,7 @@ static int generic_xdp_install(struct net_device *dev, struct netdev_bpf *xdp)
 		} else if (new && !old) {
 			static_key_slow_inc(&generic_xdp_needed);
 			dev_disable_lro(dev);
+			dev_disable_gro_hw(dev);
 		}
 		break;
 
@@ -7424,6 +7442,18 @@ static netdev_features_t netdev_fix_features(struct net_device *dev,
 		features &= ~dev->gso_partial_features;
 	}
 
+	if (!(features & NETIF_F_RXCSUM)) {
+		/* NETIF_F_GRO_HW implies doing RXCSUM since every packet
+		 * successfully merged by hardware must also have the
+		 * checksum verified by hardware.  If the user does not
+		 * want to enable RXCSUM, logically, we should disable GRO_HW.
+		 */
+		if (features & NETIF_F_GRO_HW) {
+			netdev_dbg(dev, "Dropping NETIF_F_GRO_HW since no RXCSUM feature.\n");
+			features &= ~NETIF_F_GRO_HW;
+		}
+	}
+
 	return features;
 }