[PATCH 0/2] sctp: Add GSO support

[PATCH 0/2] sctp: Add GSO support

[Marcelo Ricardo Leitner]

This patchset adds sctp GSO support.

Performance tests indicates that increases throughput by 10% if using
bigger chunk sizes, specially if bigger than MTU. For small chunks, it
doesn't help much if not using heavy firewall rules.

For small chunks it will probably be of more use once we get something
like MSG_MORE as David Laight had suggested.

I believe I could address all comments from the RFC attempt.

Marcelo Ricardo Leitner (2):
  skbuff: export skb_gro_receive
  sctp: Add GSO support

 include/linux/netdev_features.h |   7 +-
 include/linux/netdevice.h       |   1 +
 include/linux/skbuff.h          |   7 +
 include/net/sctp/sctp.h         |   4 +
 include/net/sctp/structs.h      |   2 +
 net/core/skbuff.c               |  11 +-
 net/ipv4/af_inet.c              |   1 +
 net/sctp/Makefile               |   3 +-
 net/sctp/offload.c              |  98 +++++++++++
 net/sctp/output.c               | 348 +++++++++++++++++++++++++++-------------
 net/sctp/protocol.c             |   3 +
 net/sctp/socket.c               |   2 +
 12 files changed, 366 insertions(+), 121 deletions(-)
 create mode 100644 net/sctp/offload.c

-- 
2.5.0

[PATCH 0/2] sctp: Add GSO support

[Marcelo Ricardo Leitner]

This patchset adds sctp GSO support.

Performance tests indicates that increases throughput by 10% if using
bigger chunk sizes, specially if bigger than MTU. For small chunks, it
doesn't help much if not using heavy firewall rules.

For small chunks it will probably be of more use once we get something
like MSG_MORE as David Laight had suggested.

I believe I could address all comments from the RFC attempt.

Marcelo Ricardo Leitner (2):
  skbuff: export skb_gro_receive
  sctp: Add GSO support

 include/linux/netdev_features.h |   7 +-
 include/linux/netdevice.h       |   1 +
 include/linux/skbuff.h          |   7 +
 include/net/sctp/sctp.h         |   4 +
 include/net/sctp/structs.h      |   2 +
 net/core/skbuff.c               |  11 +-
 net/ipv4/af_inet.c              |   1 +
 net/sctp/Makefile               |   3 +-
 net/sctp/offload.c              |  98 +++++++++++
 net/sctp/output.c               | 348 +++++++++++++++++++++++++++-------------
 net/sctp/protocol.c             |   3 +
 net/sctp/socket.c               |   2 +
 12 files changed, 366 insertions(+), 121 deletions(-)
 create mode 100644 net/sctp/offload.c

-- 
2.5.0

[PATCH 1/2] skbuff: export skb_gro_receive

[Marcelo Ricardo Leitner]

sctp GSO requires it and sctp can be compiled as a module, so we need to
export this function.

Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
---
 net/core/skbuff.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 7a1d48983f81e68b42e8beb664db9aef00440f13..1b05114baeb5e3aa4f333dccd24a97aff86892ec 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3435,6 +3435,7 @@ done:
 	NAPI_GRO_CB(skb)->same_flow = 1;
 	return 0;
 }
+EXPORT_SYMBOL_GPL(skb_gro_receive);
 
 void __init skb_init(void)
 {
-- 
2.5.0

[PATCH 1/2] skbuff: export skb_gro_receive

[Marcelo Ricardo Leitner]

sctp GSO requires it and sctp can be compiled as a module, so we need to
export this function.

Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
---
 net/core/skbuff.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 7a1d48983f81e68b42e8beb664db9aef00440f13..1b05114baeb5e3aa4f333dccd24a97aff86892ec 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3435,6 +3435,7 @@ done:
 	NAPI_GRO_CB(skb)->same_flow = 1;
 	return 0;
 }
+EXPORT_SYMBOL_GPL(skb_gro_receive);
 
 void __init skb_init(void)
 {
-- 
2.5.0

[PATCH 2/2] sctp: Add GSO support

[Marcelo Ricardo Leitner]

SCTP has this pecualiarity that its packets cannot be just segmented to
(P)MTU. Its chunks must be contained in IP segments, padding respected.
So we can't just generate a big skb, set gso_size to the fragmentation
point and deliver it to IP layer.

This patch takes a different approach. SCTP will now build a skb as it
would be if it was received using GRO. That is, there will be a cover
skb with protocol headers and children ones containing the actual
segments, already segmented to a way that respects SCTP RFCs.

With that, we can tell skb_segment() to just split based on frag_list,
trusting its sizes are already in accordance.

This way SCTP can benefit from GSO and instead of passing several
packets through the stack, it can pass a single large packet.

Tested-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
---
 include/linux/netdev_features.h |   7 +-
 include/linux/netdevice.h       |   1 +
 include/linux/skbuff.h          |   7 +
 include/net/sctp/sctp.h         |   4 +
 include/net/sctp/structs.h      |   2 +
 net/core/skbuff.c               |  10 +-
 net/ipv4/af_inet.c              |   1 +
 net/sctp/Makefile               |   3 +-
 net/sctp/offload.c              |  98 +++++++++++
 net/sctp/output.c               | 348 +++++++++++++++++++++++++++-------------
 net/sctp/protocol.c             |   3 +
 net/sctp/socket.c               |   2 +
 12 files changed, 365 insertions(+), 121 deletions(-)
 create mode 100644 net/sctp/offload.c

diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h
index bc87362667497fd845a2fcc5ad0eddbf031d1eaf..838aa14fec16cdc3814066351e4c533f64d0e340 100644
--- a/include/linux/netdev_features.h
+++ b/include/linux/netdev_features.h
@@ -53,8 +53,9 @@ enum {
 					 *     headers in software.
 					 */
 	NETIF_F_GSO_TUNNEL_REMCSUM_BIT, /* ... TUNNEL with TSO & REMCSUM */
+	NETIF_F_GSO_SCTP_BIT,		/* ... SCTP fragmentation */
 	/**/NETIF_F_GSO_LAST =		/* last bit, see GSO_MASK */
-		NETIF_F_GSO_TUNNEL_REMCSUM_BIT,
+		NETIF_F_GSO_SCTP_BIT,
 
 	NETIF_F_FCOE_CRC_BIT,		/* FCoE CRC32 */
 	NETIF_F_SCTP_CRC_BIT,		/* SCTP checksum offload */
@@ -128,6 +129,7 @@ enum {
 #define NETIF_F_TSO_MANGLEID	__NETIF_F(TSO_MANGLEID)
 #define NETIF_F_GSO_PARTIAL	 __NETIF_F(GSO_PARTIAL)
 #define NETIF_F_GSO_TUNNEL_REMCSUM __NETIF_F(GSO_TUNNEL_REMCSUM)
+#define NETIF_F_GSO_SCTP	__NETIF_F(GSO_SCTP)
 #define NETIF_F_HW_VLAN_STAG_FILTER __NETIF_F(HW_VLAN_STAG_FILTER)
 #define NETIF_F_HW_VLAN_STAG_RX	__NETIF_F(HW_VLAN_STAG_RX)
 #define NETIF_F_HW_VLAN_STAG_TX	__NETIF_F(HW_VLAN_STAG_TX)
@@ -166,7 +168,8 @@ enum {
 				 NETIF_F_FSO)
 
 /* List of features with software fallbacks. */
-#define NETIF_F_GSO_SOFTWARE	(NETIF_F_ALL_TSO | NETIF_F_UFO)
+#define NETIF_F_GSO_SOFTWARE	(NETIF_F_ALL_TSO | NETIF_F_UFO | \
+				 NETIF_F_GSO_SCTP)
 
 /*
  * If one device supports one of these features, then enable them
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 934ca866562d9ba9a9d2fb2e34f627660bd0c994..91f084d2d7e066c398cd98d3fd70eec8ec063d5d 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -4010,6 +4010,7 @@ static inline bool net_gso_ok(netdev_features_t features, int gso_type)
 	BUILD_BUG_ON(SKB_GSO_UDP_TUNNEL_CSUM != (NETIF_F_GSO_UDP_TUNNEL_CSUM >> NETIF_F_GSO_SHIFT));
 	BUILD_BUG_ON(SKB_GSO_PARTIAL != (NETIF_F_GSO_PARTIAL >> NETIF_F_GSO_SHIFT));
 	BUILD_BUG_ON(SKB_GSO_TUNNEL_REMCSUM != (NETIF_F_GSO_TUNNEL_REMCSUM >> NETIF_F_GSO_SHIFT));
+	BUILD_BUG_ON(SKB_GSO_SCTP    != (NETIF_F_GSO_SCTP >> NETIF_F_GSO_SHIFT));
 
 	return (features & feature) = feature;
 }
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index c84a5a1078c5528bf6fc84573f63f3c6f470ce8f..df557f77732e0d74a896522e0c9f864f49d6438a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -301,6 +301,11 @@ struct sk_buff;
 #endif
 extern int sysctl_max_skb_frags;
 
+/* Set skb_shinfo(skb)->gso_size to this in case you want skb_segment to
+ * segment using its current segmentation instead.
+ */
+#define GSO_BY_FRAGS	0xFFFF
+
 typedef struct skb_frag_struct skb_frag_t;
 
 struct skb_frag_struct {
@@ -482,6 +487,8 @@ enum {
 	SKB_GSO_PARTIAL = 1 << 13,
 
 	SKB_GSO_TUNNEL_REMCSUM = 1 << 14,
+
+	SKB_GSO_SCTP = 1 << 15,
 };
 
 #if BITS_PER_LONG > 32
diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index b392ac8382f2bf0be118f797a4444cc0eb4ddeb5..632e205ca54bfe85124753e09445251056e19aa7 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -186,6 +186,10 @@ void sctp_assocs_proc_exit(struct net *net);
 int sctp_remaddr_proc_init(struct net *net);
 void sctp_remaddr_proc_exit(struct net *net);
 
+/*
+ * sctp/offload.c
+ */
+int sctp_offload_init(void);
 
 /*
  * Module global variables
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 558bae3cbe0d5107d52c8cb31b324cfd5479def0..692805bff54cdab723605e100a9bdbee8db6b563 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -696,6 +696,8 @@ struct sctp_packet {
 	size_t overhead;
 	/* This is the total size of all chunks INCLUDING padding.  */
 	size_t size;
+	/* This is the maximum size this packet may have */
+	size_t max_size;
 
 	/* The packet is destined for this transport address.
 	 * The function we finally use to pass down to the next lower
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 1b05114baeb5e3aa4f333dccd24a97aff86892ec..537a20d2fe27c63cf452d3c81b4ccb7878a21619 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3113,9 +3113,13 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
 		int hsize;
 		int size;
 
-		len = head_skb->len - offset;
-		if (len > mss)
-			len = mss;
+		if (unlikely(mss = GSO_BY_FRAGS)) {
+			len = list_skb->len;
+		} else {
+			len = head_skb->len - offset;
+			if (len > mss)
+				len = mss;
+		}
 
 		hsize = skb_headlen(head_skb) - offset;
 		if (hsize < 0)
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 2e6e65fc4d203b91a06075e02d2dd1ac8141f3db..0415e4be6962e4a6c590f92497ba62aa698f235c 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1220,6 +1220,7 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
 		       SKB_GSO_TCP_FIXEDID |
 		       SKB_GSO_TUNNEL_REMCSUM |
 		       SKB_GSO_PARTIAL |
+		       SKB_GSO_SCTP |
 		       0)))
 		goto out;
 
diff --git a/net/sctp/Makefile b/net/sctp/Makefile
index 0fca5824ad0e93c905e2cbd59ff2ff7e2077ca7c..6c4f7496cec612b52e1e69664a209b4d58763be5 100644
--- a/net/sctp/Makefile
+++ b/net/sctp/Makefile
@@ -11,7 +11,8 @@ sctp-y := sm_statetable.o sm_statefuns.o sm_sideeffect.o \
 	  transport.o chunk.o sm_make_chunk.o ulpevent.o \
 	  inqueue.o outqueue.o ulpqueue.o \
 	  tsnmap.o bind_addr.o socket.o primitive.o \
-	  output.o input.o debug.o ssnmap.o auth.o
+	  output.o input.o debug.o ssnmap.o auth.o \
+	  offload.o
 
 sctp_probe-y := probe.o
 
diff --git a/net/sctp/offload.c b/net/sctp/offload.c
new file mode 100644
index 0000000000000000000000000000000000000000..9e217fce70c0025b07ba7ef5d7c921119c410382
--- /dev/null
+++ b/net/sctp/offload.c
@@ -0,0 +1,98 @@
+/*
+ * sctp_offload - GRO/GSO Offloading for SCTP
+ *
+ * Copyright (C) 2015, Marcelo Ricardo Leitner <marcelo.leitner@gmail.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 of the License, 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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/socket.h>
+#include <linux/sctp.h>
+#include <linux/proc_fs.h>
+#include <linux/vmalloc.h>
+#include <linux/module.h>
+#include <linux/kfifo.h>
+#include <linux/time.h>
+#include <net/net_namespace.h>
+
+#include <linux/skbuff.h>
+#include <net/sctp/sctp.h>
+#include <net/sctp/checksum.h>
+#include <net/protocol.h>
+
+static __le32 sctp_gso_make_checksum(struct sk_buff *skb)
+{
+	skb->ip_summed = CHECKSUM_NONE;
+	return sctp_compute_cksum(skb, skb_transport_offset(skb));
+}
+
+static struct sk_buff *sctp_gso_segment(struct sk_buff *skb,
+					netdev_features_t features)
+{
+	struct sk_buff *segs = ERR_PTR(-EINVAL);
+	struct sctphdr *sh;
+
+	sh = sctp_hdr(skb);
+	if (!pskb_may_pull(skb, sizeof(*sh)))
+		goto out;
+
+	__skb_pull(skb, sizeof(*sh));
+
+	if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
+		/* Packet is from an untrusted source, reset gso_segs. */
+		int type = skb_shinfo(skb)->gso_type;
+
+		if (unlikely(type &
+			     ~(SKB_GSO_SCTP | SKB_GSO_DODGY |
+			       0) ||
+			     !(type & (SKB_GSO_SCTP))))
+			goto out;
+
+		/* This should not happen as no NIC has SCTP GSO
+		 * offloading, it's always via software and thus we
+		 * won't send a large packet down the stack.
+		 */
+		WARN_ONCE(1, "SCTP segmentation offloading to NICs is not supported.");
+		goto out;
+	}
+
+	segs = skb_segment(skb, features | NETIF_F_HW_CSUM);
+	if (IS_ERR(segs))
+		goto out;
+
+	/* All that is left is update SCTP CRC if necessary */
+	if (!(features & NETIF_F_SCTP_CRC)) {
+		for (skb = segs; skb; skb = skb->next) {
+			if (skb->ip_summed = CHECKSUM_PARTIAL) {
+				sh = sctp_hdr(skb);
+				sh->checksum = sctp_gso_make_checksum(skb);
+			}
+		}
+	}
+
+out:
+	return segs;
+}
+
+static const struct net_offload sctp_offload = {
+	.callbacks = {
+		.gso_segment = sctp_gso_segment,
+	},
+};
+
+int __init sctp_offload_init(void)
+{
+	return inet_add_offload(&sctp_offload, IPPROTO_SCTP);
+}
diff --git a/net/sctp/output.c b/net/sctp/output.c
index 9844fe573029b9e262743440980f15277ddaf5a1..564a0e385325e0b92f9d32a8e2e3b48937800d15 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -84,18 +84,42 @@ static void sctp_packet_reset(struct sctp_packet *packet)
 struct sctp_packet *sctp_packet_config(struct sctp_packet *packet,
 				       __u32 vtag, int ecn_capable)
 {
-	struct sctp_chunk *chunk = NULL;
+	struct sctp_transport *tp = packet->transport;
+	struct sctp_association *asoc = tp->asoc;
 
 	pr_debug("%s: packet:%p vtag:0x%x\n", __func__, packet, vtag);
 
 	packet->vtag = vtag;
 
+	if (asoc && tp->dst) {
+		struct sock *sk = asoc->base.sk;
+
+		rcu_read_lock();
+		if (__sk_dst_get(sk) != tp->dst) {
+			dst_hold(tp->dst);
+			sk_setup_caps(sk, tp->dst);
+		}
+
+		if (sk_can_gso(sk)) {
+			struct net_device *dev = tp->dst->dev;
+
+			packet->max_size = dev->gso_max_size;
+		} else {
+			packet->max_size = asoc->pathmtu;
+		}
+		rcu_read_unlock();
+
+	} else {
+		packet->max_size = tp->pathmtu;
+	}
+
 	if (ecn_capable && sctp_packet_empty(packet)) {
-		chunk = sctp_get_ecne_prepend(packet->transport->asoc);
+		struct sctp_chunk *chunk;
 
 		/* If there a is a prepend chunk stick it on the list before
 		 * any other chunks get appended.
 		 */
+		chunk = sctp_get_ecne_prepend(asoc);
 		if (chunk)
 			sctp_packet_append_chunk(packet, chunk);
 	}
@@ -380,13 +404,16 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 {
 	struct sctp_transport *tp = packet->transport;
 	struct sctp_association *asoc = tp->asoc;
+	struct sock *sk = asoc->base.sk;
 	struct sctphdr *sh;
-	struct sk_buff *nskb;
+	struct sk_buff *nskb = NULL, *head = NULL;
 	struct sctp_chunk *chunk, *tmp;
-	struct sock *sk;
 	int err = 0;
 	int padding;		/* How much padding do we need?  */
+	int pkt_size;
 	__u8 has_data = 0;
+	int gso = 0;
+	int pktcount = 0;
 	struct dst_entry *dst;
 	unsigned char *auth = NULL;	/* pointer to auth in skb data */
 
@@ -400,18 +427,37 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 	chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list);
 	sk = chunk->skb->sk;
 
-	/* Allocate the new skb.  */
-	nskb = alloc_skb(packet->size + MAX_HEADER, gfp);
-	if (!nskb)
+	/* Allocate the head skb, or main one if not in GSO */
+	if (packet->size > tp->pathmtu && !packet->ipfragok) {
+		if (sk_can_gso(sk)) {
+			gso = 1;
+			pkt_size = packet->overhead;
+		} else {
+			/* If this happens, we trash this packet and try
+			 * to build a new one, hopefully correct this
+			 * time. Application may notice this error.
+			 */
+			pr_err_once("Trying to GSO but underlying device doesn't support it.");
+			goto nomem;
+		}
+	} else {
+		pkt_size = packet->size;
+	}
+	head = alloc_skb(pkt_size + MAX_HEADER, gfp);
+	if (!head)
 		goto nomem;
+	if (gso) {
+		NAPI_GRO_CB(head)->last = head;
+		skb_shinfo(head)->gso_type = sk->sk_gso_type;
+	}
 
 	/* Make sure the outbound skb has enough header room reserved. */
-	skb_reserve(nskb, packet->overhead + MAX_HEADER);
+	skb_reserve(head, packet->overhead + MAX_HEADER);
 
 	/* Set the owning socket so that we know where to get the
 	 * destination IP address.
 	 */
-	sctp_packet_set_owner_w(nskb, sk);
+	sctp_packet_set_owner_w(head, sk);
 
 	if (!sctp_transport_dst_check(tp)) {
 		sctp_transport_route(tp, NULL, sctp_sk(sk));
@@ -422,11 +468,11 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 	dst = dst_clone(tp->dst);
 	if (!dst)
 		goto no_route;
-	skb_dst_set(nskb, dst);
+	skb_dst_set(head, dst);
 
 	/* Build the SCTP header.  */
-	sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr));
-	skb_reset_transport_header(nskb);
+	sh = (struct sctphdr *)skb_push(head, sizeof(struct sctphdr));
+	skb_reset_transport_header(head);
 	sh->source = htons(packet->source_port);
 	sh->dest   = htons(packet->destination_port);
 
@@ -441,90 +487,133 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 	sh->vtag     = htonl(packet->vtag);
 	sh->checksum = 0;
 
-	/**
-	 * 6.10 Bundling
-	 *
-	 *    An endpoint bundles chunks by simply including multiple
-	 *    chunks in one outbound SCTP packet.  ...
-	 */
-
-	/**
-	 * 3.2  Chunk Field Descriptions
-	 *
-	 * The total length of a chunk (including Type, Length and
-	 * Value fields) MUST be a multiple of 4 bytes.  If the length
-	 * of the chunk is not a multiple of 4 bytes, the sender MUST
-	 * pad the chunk with all zero bytes and this padding is not
-	 * included in the chunk length field.  The sender should
-	 * never pad with more than 3 bytes.
-	 *
-	 * [This whole comment explains WORD_ROUND() below.]
-	 */
-
 	pr_debug("***sctp_transmit_packet***\n");
 
-	list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
-		list_del_init(&chunk->list);
-		if (sctp_chunk_is_data(chunk)) {
-			/* 6.3.1 C4) When data is in flight and when allowed
-			 * by rule C5, a new RTT measurement MUST be made each
-			 * round trip.  Furthermore, new RTT measurements
-			 * SHOULD be made no more than once per round-trip
-			 * for a given destination transport address.
-			 */
+	do {
+		/* Set up convenience variables... */
+		chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list);
+		pktcount++;
 
-			if (!chunk->resent && !tp->rto_pending) {
-				chunk->rtt_in_progress = 1;
-				tp->rto_pending = 1;
+		/* Calculate packet size, so it fits in PMTU. Leave
+		 * other chunks for the next packets.
+		 */
+		if (gso) {
+			pkt_size = packet->overhead;
+			list_for_each_entry(chunk, &packet->chunk_list, list) {
+				int padded = WORD_ROUND(chunk->skb->len);
+
+				if (pkt_size + padded > tp->pathmtu)
+					break;
+				pkt_size += padded;
 			}
 
-			has_data = 1;
-		}
+			/* Allocate the new skb.  */
+			nskb = alloc_skb(pkt_size + MAX_HEADER, gfp);
+			if (!nskb)
+				goto nomem;
 
-		padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len;
-		if (padding)
-			memset(skb_put(chunk->skb, padding), 0, padding);
+			/* Make sure the outbound skb has enough header
+			 * room reserved.
+			 */
+			skb_reserve(nskb, packet->overhead + MAX_HEADER);
+		} else {
+			nskb = head;
+		}
 
-		/* if this is the auth chunk that we are adding,
-		 * store pointer where it will be added and put
-		 * the auth into the packet.
+		/**
+		 * 3.2  Chunk Field Descriptions
+		 *
+		 * The total length of a chunk (including Type, Length and
+		 * Value fields) MUST be a multiple of 4 bytes.  If the length
+		 * of the chunk is not a multiple of 4 bytes, the sender MUST
+		 * pad the chunk with all zero bytes and this padding is not
+		 * included in the chunk length field.  The sender should
+		 * never pad with more than 3 bytes.
+		 *
+		 * [This whole comment explains WORD_ROUND() below.]
 		 */
-		if (chunk = packet->auth)
-			auth = skb_tail_pointer(nskb);
 
-		memcpy(skb_put(nskb, chunk->skb->len),
+		pkt_size -= packet->overhead;
+		list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
+			list_del_init(&chunk->list);
+			if (sctp_chunk_is_data(chunk)) {
+				/* 6.3.1 C4) When data is in flight and when allowed
+				 * by rule C5, a new RTT measurement MUST be made each
+				 * round trip.  Furthermore, new RTT measurements
+				 * SHOULD be made no more than once per round-trip
+				 * for a given destination transport address.
+				 */
+
+				if (!chunk->resent && !tp->rto_pending) {
+					chunk->rtt_in_progress = 1;
+					tp->rto_pending = 1;
+				}
+
+				has_data = 1;
+			}
+
+			padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len;
+			if (padding)
+				memset(skb_put(chunk->skb, padding), 0, padding);
+
+			/* if this is the auth chunk that we are adding,
+			 * store pointer where it will be added and put
+			 * the auth into the packet.
+			 */
+			if (chunk = packet->auth)
+				auth = skb_tail_pointer(nskb);
+
+			memcpy(skb_put(nskb, chunk->skb->len),
 			       chunk->skb->data, chunk->skb->len);
 
-		pr_debug("*** Chunk:%p[%s] %s 0x%x, length:%d, chunk->skb->len:%d, "
-			 "rtt_in_progress:%d\n", chunk,
-			 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
-			 chunk->has_tsn ? "TSN" : "No TSN",
-			 chunk->has_tsn ? ntohl(chunk->subh.data_hdr->tsn) : 0,
-			 ntohs(chunk->chunk_hdr->length), chunk->skb->len,
-			 chunk->rtt_in_progress);
-
-		/*
-		 * If this is a control chunk, this is our last
-		 * reference. Free data chunks after they've been
-		 * acknowledged or have failed.
-		 */
-		if (!sctp_chunk_is_data(chunk))
-			sctp_chunk_free(chunk);
-	}
+			pr_debug("*** Chunk:%p[%s] %s 0x%x, length:%d, chunk->skb->len:%d, rtt_in_progress:%d\n",
+				 chunk,
+				 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
+				 chunk->has_tsn ? "TSN" : "No TSN",
+				 chunk->has_tsn ? ntohl(chunk->subh.data_hdr->tsn) : 0,
+				 ntohs(chunk->chunk_hdr->length), chunk->skb->len,
+				 chunk->rtt_in_progress);
+
+			/* If this is a control chunk, this is our last
+			 * reference. Free data chunks after they've been
+			 * acknowledged or have failed.
+			 * Re-queue auth chunks if needed.
+			 */
+			pkt_size -= WORD_ROUND(chunk->skb->len);
 
-	/* SCTP-AUTH, Section 6.2
-	 *    The sender MUST calculate the MAC as described in RFC2104 [2]
-	 *    using the hash function H as described by the MAC Identifier and
-	 *    the shared association key K based on the endpoint pair shared key
-	 *    described by the shared key identifier.  The 'data' used for the
-	 *    computation of the AUTH-chunk is given by the AUTH chunk with its
-	 *    HMAC field set to zero (as shown in Figure 6) followed by all
-	 *    chunks that are placed after the AUTH chunk in the SCTP packet.
-	 */
-	if (auth)
-		sctp_auth_calculate_hmac(asoc, nskb,
-					 (struct sctp_auth_chunk *)auth,
-					 gfp);
+			if (chunk = packet->auth && !list_empty(&packet->chunk_list))
+				list_add(&chunk->list, &packet->chunk_list);
+			else if (!sctp_chunk_is_data(chunk))
+				sctp_chunk_free(chunk);
+
+			if (!pkt_size)
+				break;
+		}
+
+		/* SCTP-AUTH, Section 6.2
+		 *    The sender MUST calculate the MAC as described in RFC2104 [2]
+		 *    using the hash function H as described by the MAC Identifier and
+		 *    the shared association key K based on the endpoint pair shared key
+		 *    described by the shared key identifier.  The 'data' used for the
+		 *    computation of the AUTH-chunk is given by the AUTH chunk with its
+		 *    HMAC field set to zero (as shown in Figure 6) followed by all
+		 *    chunks that are placed after the AUTH chunk in the SCTP packet.
+		 */
+		if (auth)
+			sctp_auth_calculate_hmac(asoc, nskb,
+						 (struct sctp_auth_chunk *)auth,
+						 gfp);
+
+		if (!gso)
+			break;
+
+		if (skb_gro_receive(&head, nskb))
+			goto nomem;
+		nskb = NULL;
+		if (WARN_ON_ONCE(skb_shinfo(head)->gso_segs >+				 sk->sk_gso_max_segs))
+			goto nomem;
+	} while (!list_empty(&packet->chunk_list));
 
 	/* 2) Calculate the Adler-32 checksum of the whole packet,
 	 *    including the SCTP common header and all the
@@ -532,16 +621,18 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 	 *
 	 * Note: Adler-32 is no longer applicable, as has been replaced
 	 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
+	 *
+	 * If it's a GSO packet, it's postponed to sctp_skb_segment.
 	 */
-	if (!sctp_checksum_disable) {
-		if (!(dst->dev->features & NETIF_F_SCTP_CRC) ||
-		    (dst_xfrm(dst) != NULL) || packet->ipfragok) {
-			sh->checksum = sctp_compute_cksum(nskb, 0);
+	if (!sctp_checksum_disable || gso) {
+		if (!gso && (!(dst->dev->features & NETIF_F_SCTP_CRC) ||
+			     dst_xfrm(dst) || packet->ipfragok)) {
+			sh->checksum = sctp_compute_cksum(head, 0);
 		} else {
 			/* no need to seed pseudo checksum for SCTP */
-			nskb->ip_summed = CHECKSUM_PARTIAL;
-			nskb->csum_start = skb_transport_header(nskb) - nskb->head;
-			nskb->csum_offset = offsetof(struct sctphdr, checksum);
+			head->ip_summed = CHECKSUM_PARTIAL;
+			head->csum_start = skb_transport_header(head) - head->head;
+			head->csum_offset = offsetof(struct sctphdr, checksum);
 		}
 	}
 
@@ -557,7 +648,7 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 	 * Note: The works for IPv6 layer checks this bit too later
 	 * in transmission.  See IP6_ECN_flow_xmit().
 	 */
-	tp->af_specific->ecn_capable(nskb->sk);
+	tp->af_specific->ecn_capable(sk);
 
 	/* Set up the IP options.  */
 	/* BUG: not implemented
@@ -566,7 +657,7 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 
 	/* Dump that on IP!  */
 	if (asoc) {
-		asoc->stats.opackets++;
+		asoc->stats.opackets += pktcount;
 		if (asoc->peer.last_sent_to != tp)
 			/* Considering the multiple CPU scenario, this is a
 			 * "correcter" place for last_sent_to.  --xguo
@@ -589,16 +680,32 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 		}
 	}
 
-	pr_debug("***sctp_transmit_packet*** skb->len:%d\n", nskb->len);
+	pr_debug("***sctp_transmit_packet*** skb->len:%d\n", head->len);
+
+	if (gso) {
+		skb_shinfo(head)->gso_segs = pktcount;
+		skb_shinfo(head)->gso_size = GSO_BY_FRAGS;
 
-	nskb->ignore_df = packet->ipfragok;
-	tp->af_specific->sctp_xmit(nskb, tp);
+		/* We have to refresh this in case we are xmiting to
+		 * more than one transport at a time
+		 */
+		rcu_read_lock();
+		if (__sk_dst_get(sk) != tp->dst) {
+			dst_hold(tp->dst);
+			sk_setup_caps(sk, tp->dst);
+		}
+		rcu_read_unlock();
+	}
+	head->ignore_df = packet->ipfragok;
+	tp->af_specific->sctp_xmit(head, tp);
 
 out:
 	sctp_packet_reset(packet);
 	return err;
 no_route:
-	kfree_skb(nskb);
+	kfree_skb(head);
+	if (nskb != head)
+		kfree_skb(nskb);
 
 	if (asoc)
 		IP_INC_STATS(sock_net(asoc->base.sk), IPSTATS_MIB_OUTNOROUTES);
@@ -751,39 +858,50 @@ static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet,
 					struct sctp_chunk *chunk,
 					u16 chunk_len)
 {
-	size_t psize;
-	size_t pmtu;
-	int too_big;
+	size_t psize, pmtu;
 	sctp_xmit_t retval = SCTP_XMIT_OK;
 
 	psize = packet->size;
-	pmtu  = ((packet->transport->asoc) ?
-		(packet->transport->asoc->pathmtu) :
-		(packet->transport->pathmtu));
-
-	too_big = (psize + chunk_len > pmtu);
+	if (packet->transport->asoc)
+		pmtu = packet->transport->asoc->pathmtu;
+	else
+		pmtu = packet->transport->pathmtu;
 
 	/* Decide if we need to fragment or resubmit later. */
-	if (too_big) {
-		/* It's OK to fragmet at IP level if any one of the following
+	if (psize + chunk_len > pmtu) {
+		/* It's OK to fragment at IP level if any one of the following
 		 * is true:
-		 * 	1. The packet is empty (meaning this chunk is greater
-		 * 	   the MTU)
-		 * 	2. The chunk we are adding is a control chunk
-		 * 	3. The packet doesn't have any data in it yet and data
-		 * 	requires authentication.
+		 *	1. The packet is empty (meaning this chunk is greater
+		 *	   the MTU)
+		 *	2. The packet doesn't have any data in it yet and data
+		 *	   requires authentication.
 		 */
-		if (sctp_packet_empty(packet) || !sctp_chunk_is_data(chunk) ||
+		if (sctp_packet_empty(packet) ||
 		    (!packet->has_data && chunk->auth)) {
 			/* We no longer do re-fragmentation.
 			 * Just fragment at the IP layer, if we
 			 * actually hit this condition
 			 */
 			packet->ipfragok = 1;
-		} else {
-			retval = SCTP_XMIT_PMTU_FULL;
+			goto out;
 		}
+
+		/* It is also okay to fragment if the chunk we are
+		 * adding is a control chunk, but only if current packet
+		 * is not a GSO one otherwise it causes fragmentation of
+		 * a large frame. So in this case we allow the
+		 * fragmentation by forcing it to be in a new packet.
+		 */
+		if (!sctp_chunk_is_data(chunk) && packet->has_data)
+			retval = SCTP_XMIT_PMTU_FULL;
+
+		if (psize + chunk_len > packet->max_size)
+			/* Hit GSO/PMTU limit, gotta flush */
+			retval = SCTP_XMIT_PMTU_FULL;
+
+		/* Otherwise it will fit in the GSO packet */
 	}
 
+out:
 	return retval;
 }
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index d3d50daa248b06d7a4306d903b2dad89e9d2acbd..40022ee885d7e8d9fbce3c7d9df43f57f0bcfa0e 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -1516,6 +1516,9 @@ static __init int sctp_init(void)
 	if (status)
 		goto err_v6_add_protocol;
 
+	if (sctp_offload_init() < 0)
+		pr_crit("%s: Cannot add SCTP protocol offload\n", __func__);
+
 out:
 	return status;
 err_v6_add_protocol:
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 777d0324594a33a407e9ec157a7634334b1292e2..c53f08eb61b3e0516685a94093b638979521dcb9 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4003,6 +4003,8 @@ static int sctp_init_sock(struct sock *sk)
 		return -ESOCKTNOSUPPORT;
 	}
 
+	sk->sk_gso_type = SKB_GSO_SCTP;
+
 	/* Initialize default send parameters. These parameters can be
 	 * modified with the SCTP_DEFAULT_SEND_PARAM socket option.
 	 */
-- 
2.5.0

[PATCH 2/2] sctp: Add GSO support

[Marcelo Ricardo Leitner]

SCTP has this pecualiarity that its packets cannot be just segmented to
(P)MTU. Its chunks must be contained in IP segments, padding respected.
So we can't just generate a big skb, set gso_size to the fragmentation
point and deliver it to IP layer.

This patch takes a different approach. SCTP will now build a skb as it
would be if it was received using GRO. That is, there will be a cover
skb with protocol headers and children ones containing the actual
segments, already segmented to a way that respects SCTP RFCs.

With that, we can tell skb_segment() to just split based on frag_list,
trusting its sizes are already in accordance.

This way SCTP can benefit from GSO and instead of passing several
packets through the stack, it can pass a single large packet.

Tested-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
---
 include/linux/netdev_features.h |   7 +-
 include/linux/netdevice.h       |   1 +
 include/linux/skbuff.h          |   7 +
 include/net/sctp/sctp.h         |   4 +
 include/net/sctp/structs.h      |   2 +
 net/core/skbuff.c               |  10 +-
 net/ipv4/af_inet.c              |   1 +
 net/sctp/Makefile               |   3 +-
 net/sctp/offload.c              |  98 +++++++++++
 net/sctp/output.c               | 348 +++++++++++++++++++++++++++-------------
 net/sctp/protocol.c             |   3 +
 net/sctp/socket.c               |   2 +
 12 files changed, 365 insertions(+), 121 deletions(-)
 create mode 100644 net/sctp/offload.c

diff --git a/include/linux/netdev_features.h b/include/linux/netdev_features.h
index bc87362667497fd845a2fcc5ad0eddbf031d1eaf..838aa14fec16cdc3814066351e4c533f64d0e340 100644
--- a/include/linux/netdev_features.h
+++ b/include/linux/netdev_features.h
@@ -53,8 +53,9 @@ enum {
 					 *     headers in software.
 					 */
 	NETIF_F_GSO_TUNNEL_REMCSUM_BIT, /* ... TUNNEL with TSO & REMCSUM */
+	NETIF_F_GSO_SCTP_BIT,		/* ... SCTP fragmentation */
 	/**/NETIF_F_GSO_LAST =		/* last bit, see GSO_MASK */
-		NETIF_F_GSO_TUNNEL_REMCSUM_BIT,
+		NETIF_F_GSO_SCTP_BIT,
 
 	NETIF_F_FCOE_CRC_BIT,		/* FCoE CRC32 */
 	NETIF_F_SCTP_CRC_BIT,		/* SCTP checksum offload */
@@ -128,6 +129,7 @@ enum {
 #define NETIF_F_TSO_MANGLEID	__NETIF_F(TSO_MANGLEID)
 #define NETIF_F_GSO_PARTIAL	 __NETIF_F(GSO_PARTIAL)
 #define NETIF_F_GSO_TUNNEL_REMCSUM __NETIF_F(GSO_TUNNEL_REMCSUM)
+#define NETIF_F_GSO_SCTP	__NETIF_F(GSO_SCTP)
 #define NETIF_F_HW_VLAN_STAG_FILTER __NETIF_F(HW_VLAN_STAG_FILTER)
 #define NETIF_F_HW_VLAN_STAG_RX	__NETIF_F(HW_VLAN_STAG_RX)
 #define NETIF_F_HW_VLAN_STAG_TX	__NETIF_F(HW_VLAN_STAG_TX)
@@ -166,7 +168,8 @@ enum {
 				 NETIF_F_FSO)
 
 /* List of features with software fallbacks. */
-#define NETIF_F_GSO_SOFTWARE	(NETIF_F_ALL_TSO | NETIF_F_UFO)
+#define NETIF_F_GSO_SOFTWARE	(NETIF_F_ALL_TSO | NETIF_F_UFO | \
+				 NETIF_F_GSO_SCTP)
 
 /*
  * If one device supports one of these features, then enable them
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 934ca866562d9ba9a9d2fb2e34f627660bd0c994..91f084d2d7e066c398cd98d3fd70eec8ec063d5d 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -4010,6 +4010,7 @@ static inline bool net_gso_ok(netdev_features_t features, int gso_type)
 	BUILD_BUG_ON(SKB_GSO_UDP_TUNNEL_CSUM != (NETIF_F_GSO_UDP_TUNNEL_CSUM >> NETIF_F_GSO_SHIFT));
 	BUILD_BUG_ON(SKB_GSO_PARTIAL != (NETIF_F_GSO_PARTIAL >> NETIF_F_GSO_SHIFT));
 	BUILD_BUG_ON(SKB_GSO_TUNNEL_REMCSUM != (NETIF_F_GSO_TUNNEL_REMCSUM >> NETIF_F_GSO_SHIFT));
+	BUILD_BUG_ON(SKB_GSO_SCTP    != (NETIF_F_GSO_SCTP >> NETIF_F_GSO_SHIFT));
 
 	return (features & feature) == feature;
 }
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index c84a5a1078c5528bf6fc84573f63f3c6f470ce8f..df557f77732e0d74a896522e0c9f864f49d6438a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -301,6 +301,11 @@ struct sk_buff;
 #endif
 extern int sysctl_max_skb_frags;
 
+/* Set skb_shinfo(skb)->gso_size to this in case you want skb_segment to
+ * segment using its current segmentation instead.
+ */
+#define GSO_BY_FRAGS	0xFFFF
+
 typedef struct skb_frag_struct skb_frag_t;
 
 struct skb_frag_struct {
@@ -482,6 +487,8 @@ enum {
 	SKB_GSO_PARTIAL = 1 << 13,
 
 	SKB_GSO_TUNNEL_REMCSUM = 1 << 14,
+
+	SKB_GSO_SCTP = 1 << 15,
 };
 
 #if BITS_PER_LONG > 32
diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index b392ac8382f2bf0be118f797a4444cc0eb4ddeb5..632e205ca54bfe85124753e09445251056e19aa7 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -186,6 +186,10 @@ void sctp_assocs_proc_exit(struct net *net);
 int sctp_remaddr_proc_init(struct net *net);
 void sctp_remaddr_proc_exit(struct net *net);
 
+/*
+ * sctp/offload.c
+ */
+int sctp_offload_init(void);
 
 /*
  * Module global variables
diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 558bae3cbe0d5107d52c8cb31b324cfd5479def0..692805bff54cdab723605e100a9bdbee8db6b563 100644
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -696,6 +696,8 @@ struct sctp_packet {
 	size_t overhead;
 	/* This is the total size of all chunks INCLUDING padding.  */
 	size_t size;
+	/* This is the maximum size this packet may have */
+	size_t max_size;
 
 	/* The packet is destined for this transport address.
 	 * The function we finally use to pass down to the next lower
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 1b05114baeb5e3aa4f333dccd24a97aff86892ec..537a20d2fe27c63cf452d3c81b4ccb7878a21619 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3113,9 +3113,13 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb,
 		int hsize;
 		int size;
 
-		len = head_skb->len - offset;
-		if (len > mss)
-			len = mss;
+		if (unlikely(mss == GSO_BY_FRAGS)) {
+			len = list_skb->len;
+		} else {
+			len = head_skb->len - offset;
+			if (len > mss)
+				len = mss;
+		}
 
 		hsize = skb_headlen(head_skb) - offset;
 		if (hsize < 0)
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 2e6e65fc4d203b91a06075e02d2dd1ac8141f3db..0415e4be6962e4a6c590f92497ba62aa698f235c 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1220,6 +1220,7 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
 		       SKB_GSO_TCP_FIXEDID |
 		       SKB_GSO_TUNNEL_REMCSUM |
 		       SKB_GSO_PARTIAL |
+		       SKB_GSO_SCTP |
 		       0)))
 		goto out;
 
diff --git a/net/sctp/Makefile b/net/sctp/Makefile
index 0fca5824ad0e93c905e2cbd59ff2ff7e2077ca7c..6c4f7496cec612b52e1e69664a209b4d58763be5 100644
--- a/net/sctp/Makefile
+++ b/net/sctp/Makefile
@@ -11,7 +11,8 @@ sctp-y := sm_statetable.o sm_statefuns.o sm_sideeffect.o \
 	  transport.o chunk.o sm_make_chunk.o ulpevent.o \
 	  inqueue.o outqueue.o ulpqueue.o \
 	  tsnmap.o bind_addr.o socket.o primitive.o \
-	  output.o input.o debug.o ssnmap.o auth.o
+	  output.o input.o debug.o ssnmap.o auth.o \
+	  offload.o
 
 sctp_probe-y := probe.o
 
diff --git a/net/sctp/offload.c b/net/sctp/offload.c
new file mode 100644
index 0000000000000000000000000000000000000000..9e217fce70c0025b07ba7ef5d7c921119c410382
--- /dev/null
+++ b/net/sctp/offload.c
@@ -0,0 +1,98 @@
+/*
+ * sctp_offload - GRO/GSO Offloading for SCTP
+ *
+ * Copyright (C) 2015, Marcelo Ricardo Leitner <marcelo.leitner@gmail.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 of the License, 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.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/socket.h>
+#include <linux/sctp.h>
+#include <linux/proc_fs.h>
+#include <linux/vmalloc.h>
+#include <linux/module.h>
+#include <linux/kfifo.h>
+#include <linux/time.h>
+#include <net/net_namespace.h>
+
+#include <linux/skbuff.h>
+#include <net/sctp/sctp.h>
+#include <net/sctp/checksum.h>
+#include <net/protocol.h>
+
+static __le32 sctp_gso_make_checksum(struct sk_buff *skb)
+{
+	skb->ip_summed = CHECKSUM_NONE;
+	return sctp_compute_cksum(skb, skb_transport_offset(skb));
+}
+
+static struct sk_buff *sctp_gso_segment(struct sk_buff *skb,
+					netdev_features_t features)
+{
+	struct sk_buff *segs = ERR_PTR(-EINVAL);
+	struct sctphdr *sh;
+
+	sh = sctp_hdr(skb);
+	if (!pskb_may_pull(skb, sizeof(*sh)))
+		goto out;
+
+	__skb_pull(skb, sizeof(*sh));
+
+	if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
+		/* Packet is from an untrusted source, reset gso_segs. */
+		int type = skb_shinfo(skb)->gso_type;
+
+		if (unlikely(type &
+			     ~(SKB_GSO_SCTP | SKB_GSO_DODGY |
+			       0) ||
+			     !(type & (SKB_GSO_SCTP))))
+			goto out;
+
+		/* This should not happen as no NIC has SCTP GSO
+		 * offloading, it's always via software and thus we
+		 * won't send a large packet down the stack.
+		 */
+		WARN_ONCE(1, "SCTP segmentation offloading to NICs is not supported.");
+		goto out;
+	}
+
+	segs = skb_segment(skb, features | NETIF_F_HW_CSUM);
+	if (IS_ERR(segs))
+		goto out;
+
+	/* All that is left is update SCTP CRC if necessary */
+	if (!(features & NETIF_F_SCTP_CRC)) {
+		for (skb = segs; skb; skb = skb->next) {
+			if (skb->ip_summed == CHECKSUM_PARTIAL) {
+				sh = sctp_hdr(skb);
+				sh->checksum = sctp_gso_make_checksum(skb);
+			}
+		}
+	}
+
+out:
+	return segs;
+}
+
+static const struct net_offload sctp_offload = {
+	.callbacks = {
+		.gso_segment = sctp_gso_segment,
+	},
+};
+
+int __init sctp_offload_init(void)
+{
+	return inet_add_offload(&sctp_offload, IPPROTO_SCTP);
+}
diff --git a/net/sctp/output.c b/net/sctp/output.c
index 9844fe573029b9e262743440980f15277ddaf5a1..564a0e385325e0b92f9d32a8e2e3b48937800d15 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -84,18 +84,42 @@ static void sctp_packet_reset(struct sctp_packet *packet)
 struct sctp_packet *sctp_packet_config(struct sctp_packet *packet,
 				       __u32 vtag, int ecn_capable)
 {
-	struct sctp_chunk *chunk = NULL;
+	struct sctp_transport *tp = packet->transport;
+	struct sctp_association *asoc = tp->asoc;
 
 	pr_debug("%s: packet:%p vtag:0x%x\n", __func__, packet, vtag);
 
 	packet->vtag = vtag;
 
+	if (asoc && tp->dst) {
+		struct sock *sk = asoc->base.sk;
+
+		rcu_read_lock();
+		if (__sk_dst_get(sk) != tp->dst) {
+			dst_hold(tp->dst);
+			sk_setup_caps(sk, tp->dst);
+		}
+
+		if (sk_can_gso(sk)) {
+			struct net_device *dev = tp->dst->dev;
+
+			packet->max_size = dev->gso_max_size;
+		} else {
+			packet->max_size = asoc->pathmtu;
+		}
+		rcu_read_unlock();
+
+	} else {
+		packet->max_size = tp->pathmtu;
+	}
+
 	if (ecn_capable && sctp_packet_empty(packet)) {
-		chunk = sctp_get_ecne_prepend(packet->transport->asoc);
+		struct sctp_chunk *chunk;
 
 		/* If there a is a prepend chunk stick it on the list before
 		 * any other chunks get appended.
 		 */
+		chunk = sctp_get_ecne_prepend(asoc);
 		if (chunk)
 			sctp_packet_append_chunk(packet, chunk);
 	}
@@ -380,13 +404,16 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 {
 	struct sctp_transport *tp = packet->transport;
 	struct sctp_association *asoc = tp->asoc;
+	struct sock *sk = asoc->base.sk;
 	struct sctphdr *sh;
-	struct sk_buff *nskb;
+	struct sk_buff *nskb = NULL, *head = NULL;
 	struct sctp_chunk *chunk, *tmp;
-	struct sock *sk;
 	int err = 0;
 	int padding;		/* How much padding do we need?  */
+	int pkt_size;
 	__u8 has_data = 0;
+	int gso = 0;
+	int pktcount = 0;
 	struct dst_entry *dst;
 	unsigned char *auth = NULL;	/* pointer to auth in skb data */
 
@@ -400,18 +427,37 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 	chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list);
 	sk = chunk->skb->sk;
 
-	/* Allocate the new skb.  */
-	nskb = alloc_skb(packet->size + MAX_HEADER, gfp);
-	if (!nskb)
+	/* Allocate the head skb, or main one if not in GSO */
+	if (packet->size > tp->pathmtu && !packet->ipfragok) {
+		if (sk_can_gso(sk)) {
+			gso = 1;
+			pkt_size = packet->overhead;
+		} else {
+			/* If this happens, we trash this packet and try
+			 * to build a new one, hopefully correct this
+			 * time. Application may notice this error.
+			 */
+			pr_err_once("Trying to GSO but underlying device doesn't support it.");
+			goto nomem;
+		}
+	} else {
+		pkt_size = packet->size;
+	}
+	head = alloc_skb(pkt_size + MAX_HEADER, gfp);
+	if (!head)
 		goto nomem;
+	if (gso) {
+		NAPI_GRO_CB(head)->last = head;
+		skb_shinfo(head)->gso_type = sk->sk_gso_type;
+	}
 
 	/* Make sure the outbound skb has enough header room reserved. */
-	skb_reserve(nskb, packet->overhead + MAX_HEADER);
+	skb_reserve(head, packet->overhead + MAX_HEADER);
 
 	/* Set the owning socket so that we know where to get the
 	 * destination IP address.
 	 */
-	sctp_packet_set_owner_w(nskb, sk);
+	sctp_packet_set_owner_w(head, sk);
 
 	if (!sctp_transport_dst_check(tp)) {
 		sctp_transport_route(tp, NULL, sctp_sk(sk));
@@ -422,11 +468,11 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 	dst = dst_clone(tp->dst);
 	if (!dst)
 		goto no_route;
-	skb_dst_set(nskb, dst);
+	skb_dst_set(head, dst);
 
 	/* Build the SCTP header.  */
-	sh = (struct sctphdr *)skb_push(nskb, sizeof(struct sctphdr));
-	skb_reset_transport_header(nskb);
+	sh = (struct sctphdr *)skb_push(head, sizeof(struct sctphdr));
+	skb_reset_transport_header(head);
 	sh->source = htons(packet->source_port);
 	sh->dest   = htons(packet->destination_port);
 
@@ -441,90 +487,133 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 	sh->vtag     = htonl(packet->vtag);
 	sh->checksum = 0;
 
-	/**
-	 * 6.10 Bundling
-	 *
-	 *    An endpoint bundles chunks by simply including multiple
-	 *    chunks in one outbound SCTP packet.  ...
-	 */
-
-	/**
-	 * 3.2  Chunk Field Descriptions
-	 *
-	 * The total length of a chunk (including Type, Length and
-	 * Value fields) MUST be a multiple of 4 bytes.  If the length
-	 * of the chunk is not a multiple of 4 bytes, the sender MUST
-	 * pad the chunk with all zero bytes and this padding is not
-	 * included in the chunk length field.  The sender should
-	 * never pad with more than 3 bytes.
-	 *
-	 * [This whole comment explains WORD_ROUND() below.]
-	 */
-
 	pr_debug("***sctp_transmit_packet***\n");
 
-	list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
-		list_del_init(&chunk->list);
-		if (sctp_chunk_is_data(chunk)) {
-			/* 6.3.1 C4) When data is in flight and when allowed
-			 * by rule C5, a new RTT measurement MUST be made each
-			 * round trip.  Furthermore, new RTT measurements
-			 * SHOULD be made no more than once per round-trip
-			 * for a given destination transport address.
-			 */
+	do {
+		/* Set up convenience variables... */
+		chunk = list_entry(packet->chunk_list.next, struct sctp_chunk, list);
+		pktcount++;
 
-			if (!chunk->resent && !tp->rto_pending) {
-				chunk->rtt_in_progress = 1;
-				tp->rto_pending = 1;
+		/* Calculate packet size, so it fits in PMTU. Leave
+		 * other chunks for the next packets.
+		 */
+		if (gso) {
+			pkt_size = packet->overhead;
+			list_for_each_entry(chunk, &packet->chunk_list, list) {
+				int padded = WORD_ROUND(chunk->skb->len);
+
+				if (pkt_size + padded > tp->pathmtu)
+					break;
+				pkt_size += padded;
 			}
 
-			has_data = 1;
-		}
+			/* Allocate the new skb.  */
+			nskb = alloc_skb(pkt_size + MAX_HEADER, gfp);
+			if (!nskb)
+				goto nomem;
 
-		padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len;
-		if (padding)
-			memset(skb_put(chunk->skb, padding), 0, padding);
+			/* Make sure the outbound skb has enough header
+			 * room reserved.
+			 */
+			skb_reserve(nskb, packet->overhead + MAX_HEADER);
+		} else {
+			nskb = head;
+		}
 
-		/* if this is the auth chunk that we are adding,
-		 * store pointer where it will be added and put
-		 * the auth into the packet.
+		/**
+		 * 3.2  Chunk Field Descriptions
+		 *
+		 * The total length of a chunk (including Type, Length and
+		 * Value fields) MUST be a multiple of 4 bytes.  If the length
+		 * of the chunk is not a multiple of 4 bytes, the sender MUST
+		 * pad the chunk with all zero bytes and this padding is not
+		 * included in the chunk length field.  The sender should
+		 * never pad with more than 3 bytes.
+		 *
+		 * [This whole comment explains WORD_ROUND() below.]
 		 */
-		if (chunk == packet->auth)
-			auth = skb_tail_pointer(nskb);
 
-		memcpy(skb_put(nskb, chunk->skb->len),
+		pkt_size -= packet->overhead;
+		list_for_each_entry_safe(chunk, tmp, &packet->chunk_list, list) {
+			list_del_init(&chunk->list);
+			if (sctp_chunk_is_data(chunk)) {
+				/* 6.3.1 C4) When data is in flight and when allowed
+				 * by rule C5, a new RTT measurement MUST be made each
+				 * round trip.  Furthermore, new RTT measurements
+				 * SHOULD be made no more than once per round-trip
+				 * for a given destination transport address.
+				 */
+
+				if (!chunk->resent && !tp->rto_pending) {
+					chunk->rtt_in_progress = 1;
+					tp->rto_pending = 1;
+				}
+
+				has_data = 1;
+			}
+
+			padding = WORD_ROUND(chunk->skb->len) - chunk->skb->len;
+			if (padding)
+				memset(skb_put(chunk->skb, padding), 0, padding);
+
+			/* if this is the auth chunk that we are adding,
+			 * store pointer where it will be added and put
+			 * the auth into the packet.
+			 */
+			if (chunk == packet->auth)
+				auth = skb_tail_pointer(nskb);
+
+			memcpy(skb_put(nskb, chunk->skb->len),
 			       chunk->skb->data, chunk->skb->len);
 
-		pr_debug("*** Chunk:%p[%s] %s 0x%x, length:%d, chunk->skb->len:%d, "
-			 "rtt_in_progress:%d\n", chunk,
-			 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
-			 chunk->has_tsn ? "TSN" : "No TSN",
-			 chunk->has_tsn ? ntohl(chunk->subh.data_hdr->tsn) : 0,
-			 ntohs(chunk->chunk_hdr->length), chunk->skb->len,
-			 chunk->rtt_in_progress);
-
-		/*
-		 * If this is a control chunk, this is our last
-		 * reference. Free data chunks after they've been
-		 * acknowledged or have failed.
-		 */
-		if (!sctp_chunk_is_data(chunk))
-			sctp_chunk_free(chunk);
-	}
+			pr_debug("*** Chunk:%p[%s] %s 0x%x, length:%d, chunk->skb->len:%d, rtt_in_progress:%d\n",
+				 chunk,
+				 sctp_cname(SCTP_ST_CHUNK(chunk->chunk_hdr->type)),
+				 chunk->has_tsn ? "TSN" : "No TSN",
+				 chunk->has_tsn ? ntohl(chunk->subh.data_hdr->tsn) : 0,
+				 ntohs(chunk->chunk_hdr->length), chunk->skb->len,
+				 chunk->rtt_in_progress);
+
+			/* If this is a control chunk, this is our last
+			 * reference. Free data chunks after they've been
+			 * acknowledged or have failed.
+			 * Re-queue auth chunks if needed.
+			 */
+			pkt_size -= WORD_ROUND(chunk->skb->len);
 
-	/* SCTP-AUTH, Section 6.2
-	 *    The sender MUST calculate the MAC as described in RFC2104 [2]
-	 *    using the hash function H as described by the MAC Identifier and
-	 *    the shared association key K based on the endpoint pair shared key
-	 *    described by the shared key identifier.  The 'data' used for the
-	 *    computation of the AUTH-chunk is given by the AUTH chunk with its
-	 *    HMAC field set to zero (as shown in Figure 6) followed by all
-	 *    chunks that are placed after the AUTH chunk in the SCTP packet.
-	 */
-	if (auth)
-		sctp_auth_calculate_hmac(asoc, nskb,
-					 (struct sctp_auth_chunk *)auth,
-					 gfp);
+			if (chunk == packet->auth && !list_empty(&packet->chunk_list))
+				list_add(&chunk->list, &packet->chunk_list);
+			else if (!sctp_chunk_is_data(chunk))
+				sctp_chunk_free(chunk);
+
+			if (!pkt_size)
+				break;
+		}
+
+		/* SCTP-AUTH, Section 6.2
+		 *    The sender MUST calculate the MAC as described in RFC2104 [2]
+		 *    using the hash function H as described by the MAC Identifier and
+		 *    the shared association key K based on the endpoint pair shared key
+		 *    described by the shared key identifier.  The 'data' used for the
+		 *    computation of the AUTH-chunk is given by the AUTH chunk with its
+		 *    HMAC field set to zero (as shown in Figure 6) followed by all
+		 *    chunks that are placed after the AUTH chunk in the SCTP packet.
+		 */
+		if (auth)
+			sctp_auth_calculate_hmac(asoc, nskb,
+						 (struct sctp_auth_chunk *)auth,
+						 gfp);
+
+		if (!gso)
+			break;
+
+		if (skb_gro_receive(&head, nskb))
+			goto nomem;
+		nskb = NULL;
+		if (WARN_ON_ONCE(skb_shinfo(head)->gso_segs >=
+				 sk->sk_gso_max_segs))
+			goto nomem;
+	} while (!list_empty(&packet->chunk_list));
 
 	/* 2) Calculate the Adler-32 checksum of the whole packet,
 	 *    including the SCTP common header and all the
@@ -532,16 +621,18 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 	 *
 	 * Note: Adler-32 is no longer applicable, as has been replaced
 	 * by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
+	 *
+	 * If it's a GSO packet, it's postponed to sctp_skb_segment.
 	 */
-	if (!sctp_checksum_disable) {
-		if (!(dst->dev->features & NETIF_F_SCTP_CRC) ||
-		    (dst_xfrm(dst) != NULL) || packet->ipfragok) {
-			sh->checksum = sctp_compute_cksum(nskb, 0);
+	if (!sctp_checksum_disable || gso) {
+		if (!gso && (!(dst->dev->features & NETIF_F_SCTP_CRC) ||
+			     dst_xfrm(dst) || packet->ipfragok)) {
+			sh->checksum = sctp_compute_cksum(head, 0);
 		} else {
 			/* no need to seed pseudo checksum for SCTP */
-			nskb->ip_summed = CHECKSUM_PARTIAL;
-			nskb->csum_start = skb_transport_header(nskb) - nskb->head;
-			nskb->csum_offset = offsetof(struct sctphdr, checksum);
+			head->ip_summed = CHECKSUM_PARTIAL;
+			head->csum_start = skb_transport_header(head) - head->head;
+			head->csum_offset = offsetof(struct sctphdr, checksum);
 		}
 	}
 
@@ -557,7 +648,7 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 	 * Note: The works for IPv6 layer checks this bit too later
 	 * in transmission.  See IP6_ECN_flow_xmit().
 	 */
-	tp->af_specific->ecn_capable(nskb->sk);
+	tp->af_specific->ecn_capable(sk);
 
 	/* Set up the IP options.  */
 	/* BUG: not implemented
@@ -566,7 +657,7 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 
 	/* Dump that on IP!  */
 	if (asoc) {
-		asoc->stats.opackets++;
+		asoc->stats.opackets += pktcount;
 		if (asoc->peer.last_sent_to != tp)
 			/* Considering the multiple CPU scenario, this is a
 			 * "correcter" place for last_sent_to.  --xguo
@@ -589,16 +680,32 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 		}
 	}
 
-	pr_debug("***sctp_transmit_packet*** skb->len:%d\n", nskb->len);
+	pr_debug("***sctp_transmit_packet*** skb->len:%d\n", head->len);
+
+	if (gso) {
+		skb_shinfo(head)->gso_segs = pktcount;
+		skb_shinfo(head)->gso_size = GSO_BY_FRAGS;
 
-	nskb->ignore_df = packet->ipfragok;
-	tp->af_specific->sctp_xmit(nskb, tp);
+		/* We have to refresh this in case we are xmiting to
+		 * more than one transport at a time
+		 */
+		rcu_read_lock();
+		if (__sk_dst_get(sk) != tp->dst) {
+			dst_hold(tp->dst);
+			sk_setup_caps(sk, tp->dst);
+		}
+		rcu_read_unlock();
+	}
+	head->ignore_df = packet->ipfragok;
+	tp->af_specific->sctp_xmit(head, tp);
 
 out:
 	sctp_packet_reset(packet);
 	return err;
 no_route:
-	kfree_skb(nskb);
+	kfree_skb(head);
+	if (nskb != head)
+		kfree_skb(nskb);
 
 	if (asoc)
 		IP_INC_STATS(sock_net(asoc->base.sk), IPSTATS_MIB_OUTNOROUTES);
@@ -751,39 +858,50 @@ static sctp_xmit_t sctp_packet_will_fit(struct sctp_packet *packet,
 					struct sctp_chunk *chunk,
 					u16 chunk_len)
 {
-	size_t psize;
-	size_t pmtu;
-	int too_big;
+	size_t psize, pmtu;
 	sctp_xmit_t retval = SCTP_XMIT_OK;
 
 	psize = packet->size;
-	pmtu  = ((packet->transport->asoc) ?
-		(packet->transport->asoc->pathmtu) :
-		(packet->transport->pathmtu));
-
-	too_big = (psize + chunk_len > pmtu);
+	if (packet->transport->asoc)
+		pmtu = packet->transport->asoc->pathmtu;
+	else
+		pmtu = packet->transport->pathmtu;
 
 	/* Decide if we need to fragment or resubmit later. */
-	if (too_big) {
-		/* It's OK to fragmet at IP level if any one of the following
+	if (psize + chunk_len > pmtu) {
+		/* It's OK to fragment at IP level if any one of the following
 		 * is true:
-		 * 	1. The packet is empty (meaning this chunk is greater
-		 * 	   the MTU)
-		 * 	2. The chunk we are adding is a control chunk
-		 * 	3. The packet doesn't have any data in it yet and data
-		 * 	requires authentication.
+		 *	1. The packet is empty (meaning this chunk is greater
+		 *	   the MTU)
+		 *	2. The packet doesn't have any data in it yet and data
+		 *	   requires authentication.
 		 */
-		if (sctp_packet_empty(packet) || !sctp_chunk_is_data(chunk) ||
+		if (sctp_packet_empty(packet) ||
 		    (!packet->has_data && chunk->auth)) {
 			/* We no longer do re-fragmentation.
 			 * Just fragment at the IP layer, if we
 			 * actually hit this condition
 			 */
 			packet->ipfragok = 1;
-		} else {
-			retval = SCTP_XMIT_PMTU_FULL;
+			goto out;
 		}
+
+		/* It is also okay to fragment if the chunk we are
+		 * adding is a control chunk, but only if current packet
+		 * is not a GSO one otherwise it causes fragmentation of
+		 * a large frame. So in this case we allow the
+		 * fragmentation by forcing it to be in a new packet.
+		 */
+		if (!sctp_chunk_is_data(chunk) && packet->has_data)
+			retval = SCTP_XMIT_PMTU_FULL;
+
+		if (psize + chunk_len > packet->max_size)
+			/* Hit GSO/PMTU limit, gotta flush */
+			retval = SCTP_XMIT_PMTU_FULL;
+
+		/* Otherwise it will fit in the GSO packet */
 	}
 
+out:
 	return retval;
 }
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index d3d50daa248b06d7a4306d903b2dad89e9d2acbd..40022ee885d7e8d9fbce3c7d9df43f57f0bcfa0e 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -1516,6 +1516,9 @@ static __init int sctp_init(void)
 	if (status)
 		goto err_v6_add_protocol;
 
+	if (sctp_offload_init() < 0)
+		pr_crit("%s: Cannot add SCTP protocol offload\n", __func__);
+
 out:
 	return status;
 err_v6_add_protocol:
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 777d0324594a33a407e9ec157a7634334b1292e2..c53f08eb61b3e0516685a94093b638979521dcb9 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4003,6 +4003,8 @@ static int sctp_init_sock(struct sock *sk)
 		return -ESOCKTNOSUPPORT;
 	}
 
+	sk->sk_gso_type = SKB_GSO_SCTP;
+
 	/* Initialize default send parameters. These parameters can be
 	 * modified with the SCTP_DEFAULT_SEND_PARAM socket option.
 	 */
-- 
2.5.0

Re: [PATCH 0/2] sctp: Add GSO support

[Marcelo Ricardo Leitner]

Cc'ing Xin. Sorry Xin.

On Fri, Apr 29, 2016 at 06:33:31PM -0300, Marcelo Ricardo Leitner wrote:
> This patchset adds sctp GSO support.
> 
> Performance tests indicates that increases throughput by 10% if using
> bigger chunk sizes, specially if bigger than MTU. For small chunks, it
> doesn't help much if not using heavy firewall rules.
> 
> For small chunks it will probably be of more use once we get something
> like MSG_MORE as David Laight had suggested.
> 
> I believe I could address all comments from the RFC attempt.
> 
> Marcelo Ricardo Leitner (2):
>   skbuff: export skb_gro_receive
>   sctp: Add GSO support
> 
>  include/linux/netdev_features.h |   7 +-
>  include/linux/netdevice.h       |   1 +
>  include/linux/skbuff.h          |   7 +
>  include/net/sctp/sctp.h         |   4 +
>  include/net/sctp/structs.h      |   2 +
>  net/core/skbuff.c               |  11 +-
>  net/ipv4/af_inet.c              |   1 +
>  net/sctp/Makefile               |   3 +-
>  net/sctp/offload.c              |  98 +++++++++++
>  net/sctp/output.c               | 348 +++++++++++++++++++++++++++-------------
>  net/sctp/protocol.c             |   3 +
>  net/sctp/socket.c               |   2 +
>  12 files changed, 366 insertions(+), 121 deletions(-)
>  create mode 100644 net/sctp/offload.c
> 
> -- 

Re: [PATCH 0/2] sctp: Add GSO support

[Marcelo Ricardo Leitner]

Cc'ing Xin. Sorry Xin.

On Fri, Apr 29, 2016 at 06:33:31PM -0300, Marcelo Ricardo Leitner wrote:
> This patchset adds sctp GSO support.
> 
> Performance tests indicates that increases throughput by 10% if using
> bigger chunk sizes, specially if bigger than MTU. For small chunks, it
> doesn't help much if not using heavy firewall rules.
> 
> For small chunks it will probably be of more use once we get something
> like MSG_MORE as David Laight had suggested.
> 
> I believe I could address all comments from the RFC attempt.
> 
> Marcelo Ricardo Leitner (2):
>   skbuff: export skb_gro_receive
>   sctp: Add GSO support
> 
>  include/linux/netdev_features.h |   7 +-
>  include/linux/netdevice.h       |   1 +
>  include/linux/skbuff.h          |   7 +
>  include/net/sctp/sctp.h         |   4 +
>  include/net/sctp/structs.h      |   2 +
>  net/core/skbuff.c               |  11 +-
>  net/ipv4/af_inet.c              |   1 +
>  net/sctp/Makefile               |   3 +-
>  net/sctp/offload.c              |  98 +++++++++++
>  net/sctp/output.c               | 348 +++++++++++++++++++++++++++-------------
>  net/sctp/protocol.c             |   3 +
>  net/sctp/socket.c               |   2 +
>  12 files changed, 366 insertions(+), 121 deletions(-)
>  create mode 100644 net/sctp/offload.c
> 
> -- 

Re: [PATCH 0/2] sctp: Add GSO support

[David Miller]

From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Date: Fri, 29 Apr 2016 18:33:31 -0300

> This patchset adds sctp GSO support.
> 
> Performance tests indicates that increases throughput by 10% if using
> bigger chunk sizes, specially if bigger than MTU. For small chunks, it
> doesn't help much if not using heavy firewall rules.
> 
> For small chunks it will probably be of more use once we get something
> like MSG_MORE as David Laight had suggested.
> 
> I believe I could address all comments from the RFC attempt.

Are these packets idempotent?

Ie. if we GRO a bunch of SCTP frames on receive and that GRO frame is
forwarded rather than received locally, is the same exact packet
stream emitted on transmit?

Re: [PATCH 0/2] sctp: Add GSO support

[David Miller]

From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Date: Fri, 29 Apr 2016 18:33:31 -0300

> This patchset adds sctp GSO support.
> 
> Performance tests indicates that increases throughput by 10% if using
> bigger chunk sizes, specially if bigger than MTU. For small chunks, it
> doesn't help much if not using heavy firewall rules.
> 
> For small chunks it will probably be of more use once we get something
> like MSG_MORE as David Laight had suggested.
> 
> I believe I could address all comments from the RFC attempt.

Are these packets idempotent?

Ie. if we GRO a bunch of SCTP frames on receive and that GRO frame is
forwarded rather than received locally, is the same exact packet
stream emitted on transmit?

Re: [PATCH 0/2] sctp: Add GSO support

[Marcelo Ricardo Leitner]

On Mon, May 02, 2016 at 07:16:14PM -0400, David Miller wrote:
> From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
> Date: Fri, 29 Apr 2016 18:33:31 -0300
> 
> > This patchset adds sctp GSO support.
> > 
> > Performance tests indicates that increases throughput by 10% if using
> > bigger chunk sizes, specially if bigger than MTU. For small chunks, it
> > doesn't help much if not using heavy firewall rules.
> > 
> > For small chunks it will probably be of more use once we get something
> > like MSG_MORE as David Laight had suggested.
> > 
> > I believe I could address all comments from the RFC attempt.
> 
> Are these packets idempotent?
> 
> Ie. if we GRO a bunch of SCTP frames on receive and that GRO frame is
> forwarded rather than received locally, is the same exact packet
> stream emitted on transmit?

Forward path is not going to happen because we can't do GRO for SCTP,
unfortunatelly. We would have to somehow maintain frame boundaries (as
I did for GSO here) (so that AUTH chunks have a delimited scope, for
example) and that's not feasible with the current way we do GRO. Well,
at least I couldn't see how.

So this is just for pure tx path, no forwarding involved.

  Marcelo

Re: [PATCH 0/2] sctp: Add GSO support

[Marcelo Ricardo Leitner]

On Mon, May 02, 2016 at 07:16:14PM -0400, David Miller wrote:
> From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
> Date: Fri, 29 Apr 2016 18:33:31 -0300
> 
> > This patchset adds sctp GSO support.
> > 
> > Performance tests indicates that increases throughput by 10% if using
> > bigger chunk sizes, specially if bigger than MTU. For small chunks, it
> > doesn't help much if not using heavy firewall rules.
> > 
> > For small chunks it will probably be of more use once we get something
> > like MSG_MORE as David Laight had suggested.
> > 
> > I believe I could address all comments from the RFC attempt.
> 
> Are these packets idempotent?
> 
> Ie. if we GRO a bunch of SCTP frames on receive and that GRO frame is
> forwarded rather than received locally, is the same exact packet
> stream emitted on transmit?

Forward path is not going to happen because we can't do GRO for SCTP,
unfortunatelly. We would have to somehow maintain frame boundaries (as
I did for GSO here) (so that AUTH chunks have a delimited scope, for
example) and that's not feasible with the current way we do GRO. Well,
at least I couldn't see how.

So this is just for pure tx path, no forwarding involved.

  Marcelo

Re: [PATCH 0/2] sctp: Add GSO support

[David Miller]

From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Date: Tue, 3 May 2016 08:49:18 -0300

> So this is just for pure tx path, no forwarding involved.

And if that GSO segment is looped back into the stack via the
loopback interface, the packet classifier mirror action, or
netfilter?

You cannot just GSO things and then not handle such packets
properly on receive.

Re: [PATCH 0/2] sctp: Add GSO support

[David Miller]

From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Date: Tue, 3 May 2016 08:49:18 -0300

> So this is just for pure tx path, no forwarding involved.

And if that GSO segment is looped back into the stack via the
loopback interface, the packet classifier mirror action, or
netfilter?

You cannot just GSO things and then not handle such packets
properly on receive.

Re: [PATCH 0/2] sctp: Add GSO support

[Marcelo Ricardo Leitner]

On Tue, May 03, 2016 at 12:09:15PM -0400, David Miller wrote:
> From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
> Date: Tue, 3 May 2016 08:49:18 -0300
> 
> > So this is just for pure tx path, no forwarding involved.
> 
> And if that GSO segment is looped back into the stack via the
> loopback interface, the packet classifier mirror action, or
> netfilter?
> 
> You cannot just GSO things and then not handle such packets
> properly on receive.

Good point. It will fail if one uses AUTH due to the reason I mentioned
for GRO. I have to split the GSO packet upon rx too and that should do
it. Will post a v2 when I have it.

Thanks,
Marcelo

Re: [PATCH 0/2] sctp: Add GSO support

[Marcelo Ricardo Leitner]

On Tue, May 03, 2016 at 12:09:15PM -0400, David Miller wrote:
> From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
> Date: Tue, 3 May 2016 08:49:18 -0300
> 
> > So this is just for pure tx path, no forwarding involved.
> 
> And if that GSO segment is looped back into the stack via the
> loopback interface, the packet classifier mirror action, or
> netfilter?
> 
> You cannot just GSO things and then not handle such packets
> properly on receive.

Good point. It will fail if one uses AUTH due to the reason I mentioned
for GRO. I have to split the GSO packet upon rx too and that should do
it. Will post a v2 when I have it.

Thanks,
Marcelo