net: vlan: add support for tunnel offload (7dad9937) · Commits · 戴 / test

GSO tunneled packets are always segmented in software before they are transmitted by a VLAN, even when the lower device can offload tunnel encapsulation and VLAN together (i.e., some bits in NETIF_F_GSO_ENCAP_ALL mask are set in the lower device 'vlan_features'). If we let VLANs have the same tunnel offload capabilities as their lower device, throughput can improve significantly when CPU is limited on the transmitter side. - set NETIF_F_GSO_ENCAP_ALL bits in the VLAN 'hw_features', to ensure that 'features' will have those bits zeroed only when the lower device has no hardware support for tunnel encapsulation. - for the same reason, copy GSO-related bits of 'hw_enc_features' from lower device to VLAN, and ensure to update that value when the lower device changes its features. - set NETIF_F_HW_CSUM bit in the VLAN 'hw_enc_features' if 'real_dev' is able to compute checksums at least for a kind of packets, like done with commit ("vlan: Keep NETIF_F_HW_CSUM similar to other software devices"). This avoids software segmentation due to mismatching checksum capabilities between VLAN's 'features' and 'hw_enc_features'. Reported-by:

Flavio Leitner <fbl@redhat.com> Signed-off-by:

Davide Caratti <dcaratti@redhat.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/8021q/vlan.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -330,6 +330,7 @@ static void vlan_transfer_features(struct net_device *dev,

		vlandev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
		vlandev->priv_flags \|= (vlan->real_dev->priv_flags & IFF_XMIT_DST_RELEASE);
		vlandev->hw_enc_features = vlan_tnl_features(vlan->real_dev);

		netdev_update_features(vlandev);
		}

net/8021q/vlan.h

+12 −0

Original line number	Diff line number	Diff line
		@@ -92,6 +92,18 @@ static inline struct net_device vlan_find_dev(struct net_device real_dev,
		return NULL;
		}

		static inline netdev_features_t vlan_tnl_features(struct net_device *real_dev)
		{
		netdev_features_t ret;

		ret = real_dev->hw_enc_features &
		(NETIF_F_CSUM_MASK \| NETIF_F_ALL_TSO \| NETIF_F_GSO_ENCAP_ALL);

		if ((ret & NETIF_F_GSO_ENCAP_ALL) && (ret & NETIF_F_CSUM_MASK))
		return (ret & ~NETIF_F_CSUM_MASK) \| NETIF_F_HW_CSUM;
		return 0;
		}

		#define vlan_group_for_each_dev(grp, i, dev) \
		for ((i) = 0; i < VLAN_PROTO_NUM * VLAN_N_VID; i++) \
		if (((dev) = __vlan_group_get_device((grp), (i) / VLAN_N_VID, \

net/8021q/vlan_dev.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -562,6 +562,7 @@ static int vlan_dev_init(struct net_device *dev)

		dev->hw_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_SCTP_CRC \|
		NETIF_F_ALL_FCOE;

		@@ -572,6 +573,7 @@ static int vlan_dev_init(struct net_device *dev)
		netdev_warn(real_dev, "VLAN features are set incorrectly. Q-in-Q configurations may not work correctly.\n");

		dev->vlan_features = real_dev->vlan_features & ~NETIF_F_ALL_FCOE;
		dev->hw_enc_features = vlan_tnl_features(real_dev);

		/* ipv6 shared card related stuff */
		dev->dev_id = real_dev->dev_id;

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