[PATCHv2 net-next 1/5] net: add a common function to compute features from lowers devices

[Hangbin Liu <liuhangbin@gmail.com>]

Some high level virtual drivers need to compute features from lower
devices. But each has their own implementations and may lost some
feature compute. Let's use one common function to compute features
for kinds of these devices.

The new helper uses the current bond implementation as the reference
one, as the latter already handles all the relevant aspects: netdev
features, TSO limits and dst retention.

Suggested-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 include/linux/netdevice.h | 19 ++++++++++
 net/core/dev.c            | 76 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 95 insertions(+)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index f3a3b761abfb..42742a47f2c6 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -5279,6 +5279,25 @@ int __netdev_update_features(struct net_device *dev);
 void netdev_update_features(struct net_device *dev);
 void netdev_change_features(struct net_device *dev);
 
+/* netdevice features */
+#define VIRTUAL_DEV_VLAN_FEATURES	(NETIF_F_HW_CSUM | NETIF_F_SG | \
+					 NETIF_F_FRAGLIST | NETIF_F_GSO_SOFTWARE | \
+					 NETIF_F_GSO_ENCAP_ALL | \
+					 NETIF_F_HIGHDMA | NETIF_F_LRO)
+
+#define VIRTUAL_DEV_ENC_FEATURES	(NETIF_F_HW_CSUM | NETIF_F_SG | \
+					 NETIF_F_RXCSUM | NETIF_F_GSO_SOFTWARE | \
+					 NETIF_F_GSO_PARTIAL)
+
+#define VIRTUAL_DEV_MPLS_FEATURES	(NETIF_F_HW_CSUM | NETIF_F_SG | \
+					 NETIF_F_GSO_SOFTWARE)
+
+#define VIRTUAL_DEV_XFRM_FEATURES	(NETIF_F_HW_ESP | NETIF_F_HW_ESP_TX_CSUM | \
+					 NETIF_F_GSO_ESP)
+
+#define VIRTUAL_DEV_GSO_PARTIAL_FEATURES (NETIF_F_GSO_ESP)
+void netdev_compute_features_from_lowers(struct net_device *dev);
+
 void netif_stacked_transfer_operstate(const struct net_device *rootdev,
 					struct net_device *dev);
 
diff --git a/net/core/dev.c b/net/core/dev.c
index 1d1650d9ecff..5c1c8b016c8e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -12577,6 +12577,82 @@ netdev_features_t netdev_increment_features(netdev_features_t all,
 }
 EXPORT_SYMBOL(netdev_increment_features);
 
+/**
+ *	netdev_compute_features_from_lowers - compute feature from lowers
+ *	@dev: the upper device
+ *
+ *	Recompute the upper device's feature based on all lower devices.
+ */
+void netdev_compute_features_from_lowers(struct net_device *dev)
+{
+	unsigned int dst_release_flag = IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM;
+	netdev_features_t gso_partial_features = VIRTUAL_DEV_GSO_PARTIAL_FEATURES;
+#ifdef CONFIG_XFRM_OFFLOAD
+	netdev_features_t xfrm_features  = VIRTUAL_DEV_XFRM_FEATURES;
+#endif
+	netdev_features_t mpls_features  = VIRTUAL_DEV_MPLS_FEATURES;
+	netdev_features_t vlan_features = VIRTUAL_DEV_VLAN_FEATURES;
+	netdev_features_t enc_features  = VIRTUAL_DEV_ENC_FEATURES;
+	unsigned int tso_max_size = TSO_MAX_SIZE;
+	u16 tso_max_segs = TSO_MAX_SEGS;
+	struct net_device *lower_dev;
+	struct list_head *iter;
+
+	mpls_features = netdev_base_features(mpls_features);
+	vlan_features = netdev_base_features(vlan_features);
+	enc_features = netdev_base_features(enc_features);
+
+	netdev_for_each_lower_dev(dev, lower_dev, iter) {
+		gso_partial_features = netdev_increment_features(gso_partial_features,
+								 lower_dev->gso_partial_features,
+								 VIRTUAL_DEV_GSO_PARTIAL_FEATURES);
+
+		vlan_features = netdev_increment_features(vlan_features,
+							  lower_dev->vlan_features,
+							  VIRTUAL_DEV_VLAN_FEATURES);
+
+#ifdef CONFIG_XFRM_OFFLOAD
+		xfrm_features = netdev_increment_features(xfrm_features,
+							  lower_dev->hw_enc_features,
+							  VIRTUAL_DEV_XFRM_FEATURES);
+#endif
+
+		enc_features = netdev_increment_features(enc_features,
+							 lower_dev->hw_enc_features,
+							 VIRTUAL_DEV_ENC_FEATURES);
+
+		mpls_features = netdev_increment_features(mpls_features,
+							  lower_dev->mpls_features,
+							  VIRTUAL_DEV_MPLS_FEATURES);
+
+		dst_release_flag &= lower_dev->priv_flags;
+
+		tso_max_size = min(tso_max_size, lower_dev->tso_max_size);
+		tso_max_segs = min(tso_max_segs, lower_dev->tso_max_segs);
+	}
+
+	dev->gso_partial_features = gso_partial_features;
+	dev->vlan_features = vlan_features;
+#ifdef CONFIG_XFRM_OFFLOAD
+	dev->hw_enc_features |= xfrm_features;
+#endif
+	dev->hw_enc_features = enc_features | NETIF_F_GSO_ENCAP_ALL |
+				    NETIF_F_HW_VLAN_CTAG_TX |
+				    NETIF_F_HW_VLAN_STAG_TX;
+	dev->mpls_features = mpls_features;
+
+	dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
+	if ((dev->priv_flags & IFF_XMIT_DST_RELEASE_PERM) &&
+	    dst_release_flag == (IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM))
+		dev->priv_flags |= IFF_XMIT_DST_RELEASE;
+
+	netif_set_tso_max_segs(dev, tso_max_segs);
+	netif_set_tso_max_size(dev, tso_max_size);
+
+	netdev_change_features(dev);
+}
+EXPORT_SYMBOL(netdev_compute_features_from_lowers);
+
 static struct hlist_head * __net_init netdev_create_hash(void)
 {
 	int i;
-- 
2.50.1