vlan: Add GRO support for non hardware accelerated vlan

Currently packets with non-hardware-accelerated vlan cannot be handled
by GRO. This causes low performance for 802.1ad and stacked vlan, as their
vlan tags are currently not stripped by hardware.

This patch adds GRO support for non-hardware-accelerated vlan and
improves receive performance of them.

Test Environment:
 vlan device (.1Q) on vlan device (.1ad) on ixgbe (82599)

Result:

- Before

$ netperf -t TCP_STREAM -H 192.168.20.2 -l 60
Recv   Send    Send
Socket Socket  Message  Elapsed
Size   Size    Size     Time     Throughput
bytes  bytes   bytes    secs.    10^6bits/sec

 87380  16384  16384    60.00    5233.17

Rx side CPU usage:
  %usr      %sys      %irq     %soft     %idle
  0.27     58.03      0.00     41.70      0.00

- After

$ netperf -t TCP_STREAM -H 192.168.20.2 -l 60
Recv   Send    Send
Socket Socket  Message  Elapsed
Size   Size    Size     Time     Throughput
bytes  bytes   bytes    secs.    10^6bits/sec

 87380  16384  16384    60.00    7586.85

Rx side CPU usage:
  %usr      %sys      %irq     %soft     %idle
  0.50     25.83      0.00     59.53     14.14

[ Register VLAN offloads with priority 10 -DaveM ]

Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 20 insertions, 0 deletions

diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index a40d29846ac2..67ce5bd3b56a 100644
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -628,4 +628,24 @@ static inline netdev_features_t vlan_features_check(const struct sk_buff *skb,
 	return features;
 }
 
+/**
+ * compare_vlan_header - Compare two vlan headers
+ * @h1: Pointer to vlan header
+ * @h2: Pointer to vlan header
+ *
+ * Compare two vlan headers, returns 0 if equal.
+ *
+ * Please note that alignment of h1 & h2 are only guaranteed to be 16 bits.
+ */
+static inline unsigned long compare_vlan_header(const struct vlan_hdr *h1,
+						const struct vlan_hdr *h2)
+{
+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
+	return *(u32 *)h1 ^ *(u32 *)h2;
+#else
+	return ((__force u32)h1->h_vlan_TCI ^ (__force u32)h2->h_vlan_TCI) |
+	       ((__force u32)h1->h_vlan_encapsulated_proto ^
+		(__force u32)h2->h_vlan_encapsulated_proto);
+#endif
+}
 #endif /* !(_LINUX_IF_VLAN_H_) */