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tuntap: hardware vlan tx support
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Inspired by commit f09e224 (macvtap: restore
vlan header on user read). This patch adds hardware vlan tx support for
tuntap. This is done by copying vlan header directly into userspace in
tun_put_user() instead of doing it through __vlan_put_tag() in
dev_hard_start_xmit(). This eliminates one unnecessary memmove() in
vlan_insert_tag() for 802.1ad and 802.1q traffic.

pktgen test shows about 20% improvement for 802.1q traffic:

Before:
  662149pps 317Mb/sec (317831520bps) errors: 0
After:
  801033pps 384Mb/sec (384495840bps) errors: 0

Cc: Basil Gor <basil.gor@gmail.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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jasowang authored and davem330 committed Jul 28, 2013
1 parent 024ec3d commit 6680ec6
Showing 1 changed file with 36 additions and 4 deletions.
40 changes: 36 additions & 4 deletions drivers/net/tun.c
Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,7 @@
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/if_tun.h>
#include <linux/if_vlan.h>
#include <linux/crc32.h>
#include <linux/nsproxy.h>
#include <linux/virtio_net.h>
Expand Down Expand Up @@ -1265,6 +1266,7 @@ static ssize_t tun_put_user(struct tun_struct *tun,
{
struct tun_pi pi = { 0, skb->protocol };
ssize_t total = 0;
int vlan_offset = 0;

if (!(tun->flags & TUN_NO_PI)) {
if ((len -= sizeof(pi)) < 0)
Expand Down Expand Up @@ -1328,11 +1330,40 @@ static ssize_t tun_put_user(struct tun_struct *tun,
total += tun->vnet_hdr_sz;
}

len = min_t(int, skb->len, len);
if (!vlan_tx_tag_present(skb)) {
len = min_t(int, skb->len, len);
} else {
int copy, ret;
struct {
__be16 h_vlan_proto;
__be16 h_vlan_TCI;
} veth;

veth.h_vlan_proto = skb->vlan_proto;
veth.h_vlan_TCI = htons(vlan_tx_tag_get(skb));

vlan_offset = offsetof(struct vlan_ethhdr, h_vlan_proto);
len = min_t(int, skb->len + VLAN_HLEN, len);

copy = min_t(int, vlan_offset, len);
ret = skb_copy_datagram_const_iovec(skb, 0, iv, total, copy);
len -= copy;
total += copy;
if (ret || !len)
goto done;

copy = min_t(int, sizeof(veth), len);
ret = memcpy_toiovecend(iv, (void *)&veth, total, copy);
len -= copy;
total += copy;
if (ret || !len)
goto done;
}

skb_copy_datagram_const_iovec(skb, 0, iv, total, len);
total += skb->len;
skb_copy_datagram_const_iovec(skb, vlan_offset, iv, total, len);
total += len;

done:
tun->dev->stats.tx_packets++;
tun->dev->stats.tx_bytes += len;

Expand Down Expand Up @@ -1691,7 +1722,8 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
tun_flow_init(tun);

dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
TUN_USER_FEATURES;
TUN_USER_FEATURES | NETIF_F_HW_VLAN_CTAG_TX |
NETIF_F_HW_VLAN_STAG_TX;
dev->features = dev->hw_features;
dev->vlan_features = dev->features;

Expand Down

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