Merge branch 'Support-fraglist-GRO-GSO'

Steffen Klassert says:

====================
Support fraglist GRO/GSO

This patchset adds support to do GRO/GSO by chaining packets
of the same flow at the SKB frag_list pointer. This avoids
the overhead to merge payloads into one big packet, and
on the other end, if GSO is needed it avoids the overhead
of splitting the big packet back to the native form.

Patch 1 adds netdev feature flags to enable fraglist GRO,
this implements one of the configuration options discussed
at netconf 2019.

Patch 2 adds a netdev software feature set that defaults to off
and assigns the new fraglist GRO feature flag to it.

Patch 3 adds the core infrastructure to do fraglist GRO/GSO.

Patch 4 enables UDP to use fraglist GRO/GSO if configured.

I have only meaningful forwarding performance measurements.
I did some tests for the local receive path with netperf and iperf,
but in this case the sender that generates the packets is the
bottleneck. So the benchmarks are not that meaningful for the
receive path.

Paolo Abeni did some benchmarks of the local receive path for the
RFC v2 version of this pachset, results can be found here:

https://www.spinics.net/lists/netdev/msg551158.html

I used my IPsec forwarding test setup for the performance measurements:

           ------------         ------------
        -->| router 1 |-------->| router 2 |--
        |  ------------         ------------  |
        |                                     |
        |       --------------------          |
        --------|Spirent Testcenter|<----------
                --------------------

net-next (September 7th 2019):

Single stream UDP frame size 1460 Bytes: 1.161.000 fps (13.5 Gbps).

----------------------------------------------------------------------

net-next (September 7th 2019) + standard UDP GRO/GSO (not implemented
in this patchset):

Single stream UDP frame size 1460 Bytes: 1.801.000 fps (21 Gbps).

----------------------------------------------------------------------

net-next (September 7th 2019) + fraglist UDP GRO/GSO:

Single stream UDP frame size 1460 Bytes: 2.860.000 fps (33.4 Gbps).

=======================================================================

net-next (January 23th 2020):

Single stream UDP frame size 1460 Bytes: 919.000 fps (10.73 Gbps).

----------------------------------------------------------------------

net-next (January 23th 2020) + fraglist UDP GRO/GSO:

Single stream UDP frame size 1460 Bytes: 2.430.000 fps (28.38 Gbps).

-----------------------------------------------------------------------

Changes from RFC v1:

- Add IPv6 support.
- Split patchset to enable UDP GRO by default before adding
  fraglist GRO support.
- Mark fraglist GRO packets as CHECKSUM_NONE.
- Take a refcount on the first segment skb when doing fraglist
  segmentation. With this we can use the same error handling
  path as with standard segmentation.

Changes from RFC v2:

- Add a netdev feature flag to configure listifyed GRO.
- Fix UDP GRO enabling for IPv6.
- Fix a rcu_read_lock() imbalance.
- Fix error path in skb_segment_list().

Changes from RFC v3:

- Rename NETIF_F_GRO_LIST to NETIF_F_GRO_FRAGLIST and add
  NETIF_F_GSO_FRAGLIST.
- Move introduction of SKB_GSO_FRAGLIST to patch 2.
- Use udpv6_encap_needed_key instead of udp_encap_needed_key in IPv6.
- Move some missplaced code from patch 5 to patch 1 where it belongs to.

Changes from RFC v4:

- Drop the 'UDP: enable GRO by default' patch for now. Standard UDP GRO
  is not changed with this patchset.
- Rebase to net-next current.

Changes fom v1 (December 18th):

- Do a full __copy_skb_header instead of tryng to find the really
  needed subset header fields. Thisa can be done later.
- Mark all fraglist GRO packets with CHECKSUM_UNNECESSARY.
- Rebase to net-next current.

Changes fom v2 (January 24th):

- Do the CHECKSUM_UNNECESSARY setting from IPv4 for IPv6 too.
====================

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

3 files changed, 16 insertions, 2 deletions

diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h
index 4b19c544c59a..34d050bb1ae6 100644
--- a/include/linux/netdev_features.h
+++ b/include/linux/netdev_features.h
@@ -53,8 +53,9 @@ enum {
 	NETIF_F_GSO_ESP_BIT,		/* ... ESP with TSO */
 	NETIF_F_GSO_UDP_BIT,		/* ... UFO, deprecated except tuntap */
 	NETIF_F_GSO_UDP_L4_BIT,		/* ... UDP payload GSO (not UFO) */
+	NETIF_F_GSO_FRAGLIST_BIT,		/* ... Fraglist GSO */
 	/**/NETIF_F_GSO_LAST =		/* last bit, see GSO_MASK */
-		NETIF_F_GSO_UDP_L4_BIT,
+		NETIF_F_GSO_FRAGLIST_BIT,
 
 	NETIF_F_FCOE_CRC_BIT,		/* FCoE CRC32 */
 	NETIF_F_SCTP_CRC_BIT,		/* SCTP checksum offload */
@@ -80,6 +81,7 @@ enum {
 
 	NETIF_F_GRO_HW_BIT,		/* Hardware Generic receive offload */
 	NETIF_F_HW_TLS_RECORD_BIT,	/* Offload TLS record */
+	NETIF_F_GRO_FRAGLIST_BIT,	/* Fraglist GRO */
 
 	/*
 	 * Add your fresh new feature above and remember to update
@@ -150,6 +152,8 @@ enum {
 #define NETIF_F_GSO_UDP_L4	__NETIF_F(GSO_UDP_L4)
 #define NETIF_F_HW_TLS_TX	__NETIF_F(HW_TLS_TX)
 #define NETIF_F_HW_TLS_RX	__NETIF_F(HW_TLS_RX)
+#define NETIF_F_GRO_FRAGLIST	__NETIF_F(GRO_FRAGLIST)
+#define NETIF_F_GSO_FRAGLIST	__NETIF_F(GSO_FRAGLIST)
 
 /* Finds the next feature with the highest number of the range of start till 0.
  */
@@ -226,6 +230,9 @@ static inline int find_next_netdev_feature(u64 feature, unsigned long start)
 /* changeable features with no special hardware requirements */
 #define NETIF_F_SOFT_FEATURES	(NETIF_F_GSO | NETIF_F_GRO)
 
+/* Changeable features with no special hardware requirements that defaults to off. */
+#define NETIF_F_SOFT_FEATURES_OFF	NETIF_F_GRO_FRAGLIST
+
 #define NETIF_F_VLAN_FEATURES	(NETIF_F_HW_VLAN_CTAG_FILTER | \
 				 NETIF_F_HW_VLAN_CTAG_RX | \
 				 NETIF_F_HW_VLAN_CTAG_TX | \
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 78e9c6c1b131..20445f94eb1c 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2326,7 +2326,8 @@ struct napi_gro_cb {
 	/* Number of gro_receive callbacks this packet already went through */
 	u8 recursion_counter:4;
 
-	/* 1 bit hole */
+	/* GRO is done by frag_list pointer chaining. */
+	u8	is_flist:1;
 
 	/* used to support CHECKSUM_COMPLETE for tunneling protocols */
 	__wsum	csum;
@@ -2694,6 +2695,7 @@ struct net_device *dev_get_by_napi_id(unsigned int napi_id);
 int netdev_get_name(struct net *net, char *name, int ifindex);
 int dev_restart(struct net_device *dev);
 int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb);
+int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb);
 
 static inline unsigned int skb_gro_offset(const struct sk_buff *skb)
 {
@@ -4570,6 +4572,7 @@ static inline bool net_gso_ok(netdev_features_t features, int gso_type)
 	BUILD_BUG_ON(SKB_GSO_ESP != (NETIF_F_GSO_ESP >> NETIF_F_GSO_SHIFT));
 	BUILD_BUG_ON(SKB_GSO_UDP != (NETIF_F_GSO_UDP >> NETIF_F_GSO_SHIFT));
 	BUILD_BUG_ON(SKB_GSO_UDP_L4 != (NETIF_F_GSO_UDP_L4 >> NETIF_F_GSO_SHIFT));
+	BUILD_BUG_ON(SKB_GSO_FRAGLIST != (NETIF_F_GSO_FRAGLIST >> NETIF_F_GSO_SHIFT));
 
 	return (features & feature) == feature;
 }
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 26beae7db264..3d13a4b717e9 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -592,6 +592,8 @@ enum {
 	SKB_GSO_UDP = 1 << 16,
 
 	SKB_GSO_UDP_L4 = 1 << 17,
+
+	SKB_GSO_FRAGLIST = 1 << 18,
 };
 
 #if BITS_PER_LONG > 32
@@ -3533,6 +3535,8 @@ void skb_scrub_packet(struct sk_buff *skb, bool xnet);
 bool skb_gso_validate_network_len(const struct sk_buff *skb, unsigned int mtu);
 bool skb_gso_validate_mac_len(const struct sk_buff *skb, unsigned int len);
 struct sk_buff *skb_segment(struct sk_buff *skb, netdev_features_t features);
+struct sk_buff *skb_segment_list(struct sk_buff *skb, netdev_features_t features,
+				 unsigned int offset);
 struct sk_buff *skb_vlan_untag(struct sk_buff *skb);
 int skb_ensure_writable(struct sk_buff *skb, int write_len);
 int __skb_vlan_pop(struct sk_buff *skb, u16 *vlan_tci);