[NET]: Generic Large Receive Offload for TCP traffic

This patch provides generic Large Receive Offload (LRO) functionality
for IPv4/TCP traffic.

LRO combines received tcp packets to a single larger tcp packet and
passes them then to the network stack in order to increase performance
(throughput). The interface supports two modes: Drivers can either
pass SKBs or fragment lists to the LRO engine.

Signed-off-by: Jan-Bernd Themann <themann@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 177 insertions, 0 deletions

diff --git a/include/linux/inet_lro.h b/include/linux/inet_lro.h
new file mode 100644
index 000000000000..e1fc1d16d3cd
--- /dev/null
+++ b/include/linux/inet_lro.h
@@ -0,0 +1,177 @@
+/*
+ *  linux/include/linux/inet_lro.h
+ *
+ *  Large Receive Offload (ipv4 / tcp)
+ *
+ *  (C) Copyright IBM Corp. 2007
+ *
+ *  Authors:
+ *       Jan-Bernd Themann <themann@de.ibm.com>
+ *       Christoph Raisch <raisch@de.ibm.com>
+ *
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef __INET_LRO_H_
+#define __INET_LRO_H_
+
+#include <net/ip.h>
+#include <net/tcp.h>
+
+/*
+ * LRO statistics
+ */
+
+struct net_lro_stats {
+        unsigned long aggregated;
+        unsigned long flushed;
+        unsigned long no_desc;
+};
+
+/*
+ * LRO descriptor for a tcp session
+ */
+struct net_lro_desc {
+        struct sk_buff *parent;
+        struct sk_buff *last_skb;
+        struct skb_frag_struct *next_frag;
+        struct iphdr *iph;
+        struct tcphdr *tcph;
+        struct vlan_group *vgrp;
+        __wsum  data_csum;
+        u32 tcp_rcv_tsecr;
+        u32 tcp_rcv_tsval;
+        u32 tcp_ack;
+        u32 tcp_next_seq;
+        u32 skb_tot_frags_len;
+        u16 ip_tot_len;
+        u16 tcp_saw_tstamp;             /* timestamps enabled */
+        u16 tcp_window;
+        u16 vlan_tag;
+        int pkt_aggr_cnt;               /* counts aggregated packets */
+        int vlan_packet;
+        int mss;
+        int active;
+};
+
+/*
+ * Large Receive Offload (LRO) Manager
+ *
+ * Fields must be set by driver
+ */
+
+struct net_lro_mgr {
+        struct net_device *dev;
+        struct net_lro_stats stats;
+
+        /* LRO features */
+        unsigned long features;
+#define LRO_F_NAPI            1  /* Pass packets to stack via NAPI */
+#define LRO_F_EXTRACT_VLAN_ID 2  /* Set flag if VLAN IDs are extracted
+                                    from received packets and eth protocol
+                                    is still ETH_P_8021Q */
+
+        u32 ip_summed;      /* Set in non generated SKBs in page mode */
+        u32 ip_summed_aggr; /* Set in aggregated SKBs: CHECKSUM_UNNECESSARY
+                             * or CHECKSUM_NONE */
+
+        int max_desc; /* Max number of LRO descriptors  */
+        int max_aggr; /* Max number of LRO packets to be aggregated */
+
+        struct net_lro_desc *lro_arr; /* Array of LRO descriptors */
+
+        /*
+         * Optimized driver functions
+         *
+         * get_skb_header: returns tcp and ip header for packet in SKB
+         */
+        int (*get_skb_header)(struct sk_buff *skb, void **ip_hdr,
+                              void **tcpudp_hdr, u64 *hdr_flags, void *priv);
+
+        /* hdr_flags: */
+#define LRO_IPV4 1 /* ip_hdr is IPv4 header */
+#define LRO_TCP  2 /* tcpudp_hdr is TCP header */
+
+        /*
+         * get_frag_header: returns mac, tcp and ip header for packet in SKB
+         *
+         * @hdr_flags: Indicate what kind of LRO has to be done
+         *             (IPv4/IPv6/TCP/UDP)
+         */
+        int (*get_frag_header)(struct skb_frag_struct *frag, void **mac_hdr,
+                               void **ip_hdr, void **tcpudp_hdr, u64 *hdr_flags,
+                               void *priv);
+};
+
+/*
+ * Processes a SKB
+ *
+ * @lro_mgr: LRO manager to use
+ * @skb: SKB to aggregate
+ * @priv: Private data that may be used by driver functions
+ *        (for example get_tcp_ip_hdr)
+ */
+
+void lro_receive_skb(struct net_lro_mgr *lro_mgr,
+                     struct sk_buff *skb,
+                     void *priv);
+
+/*
+ * Processes a SKB with VLAN HW acceleration support
+ */
+
+void lro_vlan_hwaccel_receive_skb(struct net_lro_mgr *lro_mgr,
+                                  struct sk_buff *skb,
+                                  struct vlan_group *vgrp,
+                                  u16 vlan_tag,
+                                  void *priv);
+
+/*
+ * Processes a fragment list
+ *
+ * This functions aggregate fragments and generate SKBs do pass
+ * the packets to the stack.
+ *
+ * @lro_mgr: LRO manager to use
+ * @frags: Fragment to be processed. Must contain entire header in first
+ *         element.
+ * @len: Length of received data
+ * @true_size: Actual size of memory the fragment is consuming
+ * @priv: Private data that may be used by driver functions
+ *        (for example get_tcp_ip_hdr)
+ */
+
+void lro_receive_frags(struct net_lro_mgr *lro_mgr,
+                       struct skb_frag_struct *frags,
+                       int len, int true_size, void *priv, __wsum sum);
+
+void lro_vlan_hwaccel_receive_frags(struct net_lro_mgr *lro_mgr,
+                                    struct skb_frag_struct *frags,
+                                    int len, int true_size,
+                                    struct vlan_group *vgrp,
+                                    u16 vlan_tag,
+                                    void *priv, __wsum sum);
+
+/*
+ * Forward all aggregated SKBs held by lro_mgr to network stack
+ */
+
+void lro_flush_all(struct net_lro_mgr *lro_mgr);
+
+void lro_flush_pkt(struct net_lro_mgr *lro_mgr,
+                   struct iphdr *iph, struct tcphdr *tcph);
+
+#endif