diff mbox

example: add IPv4 fragmentation/reassembly example

Message ID 20170202144130.24097-3-maxim.uvarov@linaro.org
State Accepted
Commit f4337956ee3be1e783e2389eb5a5ceecb4b0b0ca
Headers show

Commit Message

Maxim Uvarov Feb. 2, 2017, 2:41 p.m. UTC
From: Joe Savage <joe.savage@arm.com>


Add an example application implementing lock-free IPv4 fragmentation
and reassembly functionality using ODP's packet "concat" and "split".

Signed-off-by: Joe Savage <joe.savage@arm.com>

Signed-off-by: Maxim Uvarov <maxim.uvarov@linaro.org>

---
 doc/application-api-guide/examples.dox           |   5 +
 example/Makefile.am                              |   1 +
 example/ipfragreass/.gitignore                   |   3 +
 example/ipfragreass/Makefile.am                  |  22 +
 example/ipfragreass/odp_ipfragreass.c            | 393 ++++++++++++
 example/ipfragreass/odp_ipfragreass_atomics.h    | 124 ++++
 example/ipfragreass/odp_ipfragreass_fragment.c   |  99 +++
 example/ipfragreass/odp_ipfragreass_fragment.h   |  28 +
 example/ipfragreass/odp_ipfragreass_helpers.c    | 121 ++++
 example/ipfragreass/odp_ipfragreass_helpers.h    | 129 ++++
 example/ipfragreass/odp_ipfragreass_ip.h         | 251 ++++++++
 example/ipfragreass/odp_ipfragreass_reassemble.c | 772 +++++++++++++++++++++++
 example/ipfragreass/odp_ipfragreass_reassemble.h | 211 +++++++
 example/m4/configure.m4                          |   1 +
 14 files changed, 2160 insertions(+)
 create mode 100644 example/ipfragreass/.gitignore
 create mode 100644 example/ipfragreass/Makefile.am
 create mode 100644 example/ipfragreass/odp_ipfragreass.c
 create mode 100644 example/ipfragreass/odp_ipfragreass_atomics.h
 create mode 100644 example/ipfragreass/odp_ipfragreass_fragment.c
 create mode 100644 example/ipfragreass/odp_ipfragreass_fragment.h
 create mode 100644 example/ipfragreass/odp_ipfragreass_helpers.c
 create mode 100644 example/ipfragreass/odp_ipfragreass_helpers.h
 create mode 100644 example/ipfragreass/odp_ipfragreass_ip.h
 create mode 100644 example/ipfragreass/odp_ipfragreass_reassemble.c
 create mode 100644 example/ipfragreass/odp_ipfragreass_reassemble.h

-- 
2.11.0.295.gd7dffce

Comments

Maxim Uvarov Feb. 2, 2017, 2:44 p.m. UTC | #1
skip that patch. Series has to be with 2 patches and this patch was in
my my dir and git am took it.

Maxim.
diff mbox

Patch

diff --git a/doc/application-api-guide/examples.dox b/doc/application-api-guide/examples.dox
index 60d4058f..80fe4670 100644
--- a/doc/application-api-guide/examples.dox
+++ b/doc/application-api-guide/examples.dox
@@ -28,3 +28,8 @@ 
  * @example odp_timer_test.c
  * ODP timer example application
  */
+
+ /**
+  * @example odp_ipfragreass.c
+  * ODP IPv4 lock-free fragmentation and reassembly example application
+  */
diff --git a/example/Makefile.am b/example/Makefile.am
index dfc07b67..9503a1ba 100644
--- a/example/Makefile.am
+++ b/example/Makefile.am
@@ -2,6 +2,7 @@  SUBDIRS = classifier \
 	  generator \
 	  hello \
 	  ipsec \
+	  ipfragreass \
 	  l2fwd_simple \
 	  l3fwd \
 	  packet \
diff --git a/example/ipfragreass/.gitignore b/example/ipfragreass/.gitignore
new file mode 100644
index 00000000..d25d7584
--- /dev/null
+++ b/example/ipfragreass/.gitignore
@@ -0,0 +1,3 @@ 
+odp_ipfragreass
+*.log
+*.trs
diff --git a/example/ipfragreass/Makefile.am b/example/ipfragreass/Makefile.am
new file mode 100644
index 00000000..d9abce9f
--- /dev/null
+++ b/example/ipfragreass/Makefile.am
@@ -0,0 +1,22 @@ 
+include $(top_srcdir)/example/Makefile.inc
+
+bin_PROGRAMS = odp_ipfragreass$(EXEEXT)
+odp_ipfragreass_LDFLAGS = $(AM_LDFLAGS) -static
+odp_ipfragreass_CFLAGS = $(AM_CFLAGS) -I${top_srcdir}/example
+
+noinst_HEADERS = \
+		  $(top_srcdir)/example/ipfragreass/odp_ipfragreass_atomics.h \
+		  $(top_srcdir)/example/ipfragreass/odp_ipfragreass_fragment.h \
+		  $(top_srcdir)/example/ipfragreass/odp_ipfragreass_helpers.h \
+		  $(top_srcdir)/example/ipfragreass/odp_ipfragreass_ip.h \
+		  $(top_srcdir)/example/ipfragreass/odp_ipfragreass_reassemble.h \
+		  $(top_srcdir)/example/example_debug.h
+
+dist_odp_ipfragreass_SOURCES = odp_ipfragreass.c \
+			       odp_ipfragreass_fragment.c \
+			       odp_ipfragreass_helpers.c \
+			       odp_ipfragreass_reassemble.c
+
+if test_example
+TESTS = odp_ipfragreass
+endif
diff --git a/example/ipfragreass/odp_ipfragreass.c b/example/ipfragreass/odp_ipfragreass.c
new file mode 100644
index 00000000..89567035
--- /dev/null
+++ b/example/ipfragreass/odp_ipfragreass.c
@@ -0,0 +1,393 @@ 
+/* Copyright (c) 2017, Linaro Limited
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier:	 BSD-3-Clause
+ */
+
+/**
+ * @file
+ *
+ * @example odp_ipfragreass.c  ODP IPv4 lock-free fragmentation and reassembly
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <assert.h>
+
+#include <odp/helper/odph_api.h>
+
+#include "odp_ipfragreass_fragment.h"
+#include "odp_ipfragreass_reassemble.h"
+#include "odp_ipfragreass_helpers.h"
+
+#define NUM_PACKETS 200   /**< Number of packets to fragment/reassemble */
+#define MAX_WORKERS 32    /**< Maximum number of worker threads */
+#define FRAGLISTS   16384 /**< Hash map size for reassembly */
+
+#define MIN_MF_FRAG_SIZE  576  /**< Minimum fragment size */
+#define MAX_PKT_LEN	  8192 /**< Maximum packet size */
+#define MAX_FRAGS_PER_PKT 6    /**< Maximum number of fragments per packet */
+
+/**
+ * Derived parameters for packet storage (inc. pool configuration)
+ */
+#define POOL_MIN_SEG_LEN IP_HDR_LEN_MIN
+#define POOL_UAREA_SIZE	 sizeof(struct packet)
+#define MAX_FRAGS	 (MAX_FRAGS_PER_PKT * NUM_PACKETS)
+
+/** Output queue for fragmentation, input queue for reassembly */
+static odp_queue_t fragments;
+
+/** Output queue for reassembly, input queue for validation */
+static odp_queue_t reassembled_pkts;
+
+/** Number of packets reassembled thus far */
+static odp_atomic_u32_t packets_reassembled;
+
+/** Number of fragments processed per thread in reassembly (for printing) */
+static struct {
+	uint32_t frags;
+} ODP_ALIGNED_CACHE thread_stats[MAX_WORKERS];
+
+/** Shared hash map structure for reassembly */
+static union fraglist *fraglists;
+
+/** Barrier for synchronising reassembly worker threads */
+static odp_barrier_t barrier;
+
+/**
+ * Initialise the base structures required for execution of this application
+ *
+ * @param[out] instance		ODP instance handle to initialise
+ * @param[out] fragment_pool	Output for fragment pool creation
+ * @param[out] shm		Output for reassembly shared memory creation
+ * @param[out] cpumask		Output for worker threads CPU mask
+ * @param[out] num_workers	Output for number of worker threads
+ */
+static void init(odp_instance_t *instance, odp_pool_t *fragment_pool,
+		 odp_shm_t *shm, odp_cpumask_t *cpumask, int *num_workers)
+{
+	unsigned int seed = time(NULL);
+	int i;
+	odp_pool_param_t pool_params;
+	odp_queue_param_t frag_queue_params;
+	odp_queue_param_t reass_queue_params;
+	char cpumask_str[ODP_CPUMASK_STR_SIZE];
+
+	srand(seed);
+	printf("= Seed: %d\n", seed);
+	printf("= MTU: %d\n", MTU);
+
+	/* ODP initialisation */
+	if (odp_init_global(instance, NULL, NULL)) {
+		fprintf(stderr, "ERROR: ODP global init failed.\n");
+		exit(1);
+	}
+	if (odp_init_local(*instance, ODP_THREAD_CONTROL)) {
+		fprintf(stderr, "ERROR: ODP local init failed.\n");
+		exit(1);
+	}
+
+	/* Create a pool for packet storage */
+	odp_pool_param_init(&pool_params);
+	pool_params.pkt.seg_len    = POOL_MIN_SEG_LEN;
+	pool_params.pkt.len	   = MAX_PKT_LEN;
+	pool_params.pkt.num	   = 2 * MAX_FRAGS + MAX_WORKERS;
+	pool_params.pkt.uarea_size = POOL_UAREA_SIZE;
+	pool_params.type	   = ODP_POOL_PACKET;
+	*fragment_pool = odp_pool_create("packet pool", &pool_params);
+	if (*fragment_pool == ODP_POOL_INVALID) {
+		fprintf(stderr, "ERROR: packet pool create failed.\n");
+		exit(1);
+	}
+
+	/* Reserve (and initialise) shared memory for reassembly fraglists */
+	*shm = odp_shm_reserve("fraglists", FRAGLISTS * sizeof(union fraglist),
+			       ODP_CACHE_LINE_SIZE, 0);
+	if (*shm == ODP_SHM_INVALID) {
+		fprintf(stderr, "ERROR: odp_shm_reserve\n");
+		exit(1);
+	}
+	fraglists = odp_shm_addr(*shm);
+	if (fraglists == NULL) {
+		fprintf(stderr, "ERROR: odp_shm_addr\n");
+		exit(1);
+	}
+	for (i = 0; i < FRAGLISTS; ++i)
+		init_fraglist(&fraglists[i]);
+
+	/* Create a queue for holding fragments */
+	odp_queue_param_init(&frag_queue_params);
+	frag_queue_params.type = ODP_QUEUE_TYPE_PLAIN;
+	frag_queue_params.enq_mode = ODP_QUEUE_OP_MT_UNSAFE;
+	fragments = odp_queue_create("fragments", &frag_queue_params);
+	if (fragments == ODP_QUEUE_INVALID) {
+		fprintf(stderr, "ERROR: odp_queue_create\n");
+		exit(1);
+	}
+
+	/* Create a queue for holding reassembled packets */
+	odp_queue_param_init(&reass_queue_params);
+	reass_queue_params.type = ODP_QUEUE_TYPE_PLAIN;
+	reass_queue_params.deq_mode = ODP_QUEUE_OP_MT_UNSAFE;
+	reassembled_pkts = odp_queue_create("reassembled packets",
+					    &reass_queue_params);
+	if (reassembled_pkts == ODP_QUEUE_INVALID) {
+		fprintf(stderr, "ERROR: odp_queue_create\n");
+		exit(1);
+	}
+
+	/* Set up worker threads */
+	*num_workers = odp_cpumask_default_worker(cpumask, *num_workers);
+	odp_barrier_init(&barrier, *num_workers + 1);
+	odp_cpumask_to_str(cpumask, cpumask_str, sizeof(cpumask_str));
+	printf("= Workers: %d\n", *num_workers);
+	printf("= CPU Mask: %s (first CPU: %d)\n\n", cpumask_str,
+	       odp_cpumask_first(cpumask));
+}
+
+/**
+ * Reassembly worker thread function
+ *
+ * Repeatedly dequeues input fragments, validating them and then passing them
+ * to the reassembly procedure "reassemble_ipv4_packets". When a packet has
+ * been reassembled, it is added to the output queue, and when NUM_PACKETS
+ * packets have been completed the function returns. Thread 0 additionally
+ * executes the garbage collection procedure to clean up stale fragments.
+ *
+ * @param arg The thread number of this worker (masquerading as a pointer)
+ *
+ * @return Always returns zero
+ */
+static int run_worker(void *arg)
+{
+	unsigned long threadno = (unsigned long)arg;
+	int iterations = 0;
+	odp_event_t ev;
+
+	odp_barrier_wait(&barrier);
+	while (odp_atomic_load_u32(&packets_reassembled) < NUM_PACKETS) {
+		odp_packet_t pkt;
+		odp_time_t timestamp;
+		odph_ipv4hdr_t *hdr;
+		struct packet *fragment;
+		int reassembled;
+
+		ev = odp_queue_deq(fragments);
+		if (ev == ODP_EVENT_INVALID)
+			break;
+		assert(odp_event_type(ev) == ODP_EVENT_PACKET);
+		++thread_stats[threadno].frags;
+
+		pkt = odp_packet_from_event(ev);
+		hdr = odp_packet_data(pkt);
+		fragment = odp_packet_user_area(pkt);
+		timestamp = odp_time_global();
+		assert(fragment != NULL);
+		assert(odp_packet_len(pkt) == ipv4hdr_payload_len(*hdr)
+					      + ipv4hdr_ihl(*hdr));
+		assert(!ipv4hdr_more_fragments(*hdr) ||
+		       (odp_packet_len(pkt) >= MIN_MF_FRAG_SIZE &&
+				(odp_packet_len(pkt)
+				 - ipv4hdr_ihl(*hdr)) % 8 == 0));
+		assert(odp_packet_len(pkt) <= MAX_PKT_LEN);
+		fragment->handle    = pkt;
+		fragment->prev      = NULL;
+		fragment->arrival.t = odp_time_to_ns(timestamp) / TS_RES_NS;
+
+		reassembled = reassemble_ipv4_packets(fraglists, FRAGLISTS,
+						      fragment, 1,
+						      reassembled_pkts);
+		if (reassembled > 0)
+			odp_atomic_add_u32(&packets_reassembled, reassembled);
+
+		/*
+		 * Perform garbage collection of stale fragments every 50
+		 * iterations. (In real applications, use a timer!)
+		 */
+		if (threadno == 0 && iterations++ > 50) {
+			iterations = 0;
+			garbage_collect_fraglists(fraglists, FRAGLISTS,
+						  reassembled_pkts, false);
+		}
+	}
+
+	while ((ev = odp_queue_deq(fragments)) != ODP_EVENT_INVALID) {
+		assert(odp_event_type(ev) == ODP_EVENT_PACKET);
+		odp_packet_free(odp_packet_from_event(ev));
+	}
+
+	return 0;
+}
+
+/**
+ * ODP fragmentation and reassembly example main function
+ */
+int main(void)
+{
+	odp_instance_t instance;
+	odp_pool_t fragment_pool;
+	odp_shm_t shm;
+	odp_cpumask_t cpumask;
+	odph_odpthread_t threads[MAX_WORKERS] = {};
+	odp_packet_t dequeued_pkts[NUM_PACKETS];
+	int i;
+	int cpu;
+	int num_workers = MAX_WORKERS;
+	int reassembled;
+
+	init(&instance, &fragment_pool, &shm, &cpumask, &num_workers);
+
+	/* Packet generation & fragmentation */
+	odp_u16be_t ip_id = 0;
+	int total_fragments = 0;
+	odp_packet_t fragment_buffer[MAX_FRAGS];
+	odp_packet_t original_packets[NUM_PACKETS];
+
+	printf("\n= Fragmenting %d packets...\n", NUM_PACKETS);
+	for (i = 0; i < NUM_PACKETS; ++i) {
+		odp_packet_t packet;
+		int num_fragments = 0;
+
+		packet = pack_udp_ipv4_packet(fragment_pool, ip_id++,
+					      MAX_PKT_LEN,
+					      MTU + IP_HDR_LEN_MAX + 1);
+		if (packet == ODP_PACKET_INVALID) {
+			fprintf(stderr, "ERROR: pack_udp_ipv4_packet\n");
+			return 1;
+		}
+
+		original_packets[i] = odp_packet_copy(packet, fragment_pool);
+		if (original_packets[i] == ODP_PACKET_INVALID) {
+			fprintf(stderr, "ERROR: odp_packet_copy\n");
+			return 1;
+		}
+
+		if (fragment_ipv4_packet(packet,
+					 &fragment_buffer[total_fragments],
+					 &num_fragments)) {
+			fprintf(stderr, "ERROR: fragment_ipv4_packet\n");
+			return 1;
+		}
+
+		total_fragments += num_fragments;
+	}
+
+	/* Shuffle the fragments around so they aren't necessarily in order */
+	printf("\n= Shuffling %d fragments...\n", total_fragments);
+	shuffle(fragment_buffer, total_fragments);
+
+	/* Insert the fragments into a queue for consumption */
+	for (i = 0; i < total_fragments; ++i) {
+		odp_event_t ev = odp_packet_to_event(fragment_buffer[i]);
+
+		if (odp_queue_enq(fragments, ev) < 0) {
+			fprintf(stderr, "ERROR: odp_queue_enq\n");
+			return 1;
+		}
+	}
+
+	/* Spawn the worker threads for reassembly */
+	for (i = 0, cpu = odp_cpumask_first(&cpumask); i < num_workers;
+	     ++i, cpu = odp_cpumask_next(&cpumask, cpu)) {
+		odp_cpumask_t thread_cpumask;
+		odph_odpthread_params_t thread_params;
+
+		memset(&thread_params, 0, sizeof(thread_params));
+		odp_cpumask_zero(&thread_cpumask);
+		thread_params.start    = run_worker;
+		thread_params.arg      = (void *)((unsigned long)i);
+		thread_params.thr_type = ODP_THREAD_WORKER;
+		thread_params.instance = instance;
+		odp_cpumask_set(&thread_cpumask, cpu);
+		odph_odpthreads_create(&threads[i], &thread_cpumask,
+				       &thread_params);
+	}
+
+	/* Go! */
+	printf("\n= Starting reassembly...\n");
+	odp_barrier_wait(&barrier);
+
+	/* Wait for all threads to complete and output statistics */
+	for (i = 0; i < num_workers; ++i) {
+		odph_odpthreads_join(&threads[i]);
+		printf("=== Thread %02d processed %3d fragments\n", i,
+		       thread_stats[i].frags);
+	}
+
+	/* Dequeue the reassembled packets */
+	{
+		odp_event_t ev;
+
+		for (reassembled = 0; (ev = odp_queue_deq(reassembled_pkts)) !=
+		     ODP_EVENT_INVALID; ++reassembled) {
+			assert(reassembled < NUM_PACKETS);
+			assert(odp_event_type(ev) == ODP_EVENT_PACKET);
+			dequeued_pkts[reassembled] = odp_packet_from_event(ev);
+		}
+	}
+
+	/* Check reassembled packets against the originals */
+	printf("\n= Checking reassembled packets...\n");
+	for (i = 0; i < reassembled; ++i) {
+		int j = -1;
+		int k;
+		odp_packet_t packet = dequeued_pkts[i];
+		uint32_t len = odp_packet_len(packet);
+		odph_ipv4hdr_t hdr;
+		odph_ipv4hdr_t reassembled_hdr;
+
+		reassembled_hdr = *(odph_ipv4hdr_t *)odp_packet_data(packet);
+		for (k = 0; k < reassembled; ++k) {
+			void *data;
+
+			data = odp_packet_data(original_packets[k]);
+			hdr = *(odph_ipv4hdr_t *)data;
+			if (hdr.src_addr == reassembled_hdr.src_addr &&
+			    hdr.dst_addr == reassembled_hdr.dst_addr &&
+			    hdr.id	 == reassembled_hdr.id &&
+			    hdr.proto	 == reassembled_hdr.proto) {
+				assert(j < 0);
+				j = k;
+			}
+		}
+		assert(j >= 0);
+
+		assert(odp_packet_is_valid(packet));
+		assert(len == odp_packet_len(original_packets[j]));
+		assert(!packet_memcmp(original_packets[j], packet, 0, 0, len));
+	}
+	printf("=== Successfully reassembled %d of %d packets\n", reassembled,
+	       NUM_PACKETS);
+	assert(reassembled == NUM_PACKETS);
+	printf("\n= Complete!\n");
+
+	/* Free packets */
+	for (i = 0; i < reassembled; ++i)
+		odp_packet_free(dequeued_pkts[i]);
+	for (i = 0; i < NUM_PACKETS; ++i)
+		odp_packet_free(original_packets[i]);
+	garbage_collect_fraglists(fraglists, FRAGLISTS,
+				  reassembled_pkts, true);
+
+	/* ODP cleanup and termination */
+	assert(!odp_queue_destroy(fragments));
+	assert(!odp_queue_destroy(reassembled_pkts));
+	assert(!odp_shm_free(shm));
+	if (odp_pool_destroy(fragment_pool)) {
+		fprintf(stderr,
+			"ERROR: fragment_pool destruction failed\n");
+		return 1;
+	}
+	if (odp_term_local()) {
+		fprintf(stderr, "ERROR: odp_term_local\n");
+		return 1;
+	}
+	if (odp_term_global(instance)) {
+		fprintf(stderr, "ERROR: odp_term_global\n");
+		return 1;
+	}
+
+	return 0;
+}
diff --git a/example/ipfragreass/odp_ipfragreass_atomics.h b/example/ipfragreass/odp_ipfragreass_atomics.h
new file mode 100644
index 00000000..52573d9d
--- /dev/null
+++ b/example/ipfragreass/odp_ipfragreass_atomics.h
@@ -0,0 +1,124 @@ 
+/* Copyright (c) 2017, Linaro Limited
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier:     BSD-3-Clause
+ */
+
+#ifndef ODP_FRAGREASS_PP_ATOMICS_H_
+#define ODP_FRAGREASS_PP_ATOMICS_H_
+
+#if defined(__arm__) || defined(__aarch64__)
+#if defined(__aarch64__)
+static inline __int128 lld(__int128 *var, int mo);
+static inline uint32_t scd(__int128 *var, __int128 neu, int mo);
+static inline bool arm_atomic_strong_compare_exchange_16(__int128 *var,
+							 __int128 *exp,
+							 __int128 neu,
+							 int mo_success,
+							 int mo_failure)
+{
+	(void)mo_failure;
+	register __int128 old;
+	register __int128 expected = *exp;
+	int ll_mo = (mo_success != __ATOMIC_RELAXED &&
+		     mo_success != __ATOMIC_RELEASE) ? __ATOMIC_ACQUIRE
+						     : __ATOMIC_RELAXED;
+	int sc_mo = (mo_success == __ATOMIC_RELEASE ||
+		     mo_success == __ATOMIC_ACQ_REL ||
+		     mo_success == __ATOMIC_SEQ_CST) ? __ATOMIC_RELEASE
+						     : __ATOMIC_RELAXED;
+
+	/*
+	 * To prevent spurious failures and ensure atomicity, we must write some
+	 * value back -- whether it's the value we wanted to write, or the value
+	 * that is currently there. Repeat until we perform a successful write.
+	 */
+	do {
+		old = lld(var, ll_mo);
+	} while (scd(var, old == expected ? neu : old, sc_mo));
+
+	*exp = old;
+	return (old == expected);
+}
+
+static inline __int128 lld(__int128 *var, int mo)
+{
+	__int128 old;
+
+	if (mo == __ATOMIC_ACQUIRE)
+		__asm__ volatile("ldaxp %0, %H0, [%1]" : "=&r" (old)
+				 : "r" (var) : "memory");
+	else /* mo == __ATOMIC_RELAXED */
+		__asm__ volatile("ldxp %0, %H0, [%1]" : "=&r" (old)
+				 : "r" (var) : );
+	return old;
+}
+
+static inline uint32_t scd(__int128 *var, __int128 neu, int mo)
+{
+	uint32_t ret;
+
+	if (mo == __ATOMIC_RELEASE)
+		__asm__ volatile("stlxp %w0, %1, %H1, [%2]" : "=&r" (ret)
+				 : "r" (neu), "r" (var) : "memory");
+	else /* mo == __ATOMIC_RELAXED */
+		__asm__ volatile("stxp %w0, %1, %H1, [%2]" : "=&r" (ret)
+				 : "r" (neu), "r" (var) : );
+	return ret;
+}
+#elif defined(__ARM_ARCH) && __ARM_ARCH == 7
+static inline uint64_t lld(uint64_t *var, int mo);
+static inline uint32_t scd(uint64_t *var, uint64_t neu, int mo);
+static inline bool arm_atomic_strong_compare_exchange_8(uint64_t *var,
+							uint64_t *exp,
+							uint64_t neu,
+							int mo_success,
+							int mo_failure)
+{
+	(void)mo_failure;
+	register uint64_t old;
+	register uint64_t expected = *exp;
+	int ll_mo = (mo_success != __ATOMIC_RELAXED &&
+		     mo_success != __ATOMIC_RELEASE) ? __ATOMIC_ACQUIRE
+						     : __ATOMIC_RELAXED;
+	int sc_mo = (mo_success == __ATOMIC_RELEASE ||
+		     mo_success == __ATOMIC_ACQ_REL ||
+		     mo_success == __ATOMIC_SEQ_CST) ? __ATOMIC_RELEASE
+						     : __ATOMIC_RELAXED;
+
+	/*
+	 * To prevent spurious failures and ensure atomicity, we must write some
+	 * value back -- whether it's the value we wanted to write, or the value
+	 * that is currently there. Repeat until we perform a successful write.
+	 */
+	do {
+		old = lld(var, ll_mo);
+	} while (scd(var, old == expected ? neu : old, sc_mo));
+
+	*exp = old;
+	return (old == expected);
+}
+
+static inline uint64_t lld(uint64_t *var, int mo)
+{
+	uint64_t old;
+
+	__asm __volatile("ldrexd %0, %H0, [%1]" : "=&r" (old) : "r" (var) : );
+	if (mo == __ATOMIC_ACQUIRE)
+		__asm__ volatile("dmb ish" ::: "memory");
+	return old;
+}
+
+static inline uint32_t scd(uint64_t *var, uint64_t neu, int mo)
+{
+	uint32_t ret;
+
+	if (mo == __ATOMIC_RELEASE)
+		__asm__ volatile("dmb ish" ::: "memory");
+	__asm __volatile("strexd %0, %1, %H1, [%2]" : "=&r" (ret)
+			 : "r" (neu), "r" (var) : );
+	return ret;
+}
+#endif
+#endif
+#endif
diff --git a/example/ipfragreass/odp_ipfragreass_fragment.c b/example/ipfragreass/odp_ipfragreass_fragment.c
new file mode 100644
index 00000000..7950a6ce
--- /dev/null
+++ b/example/ipfragreass/odp_ipfragreass_fragment.c
@@ -0,0 +1,99 @@ 
+/* Copyright (c) 2017, Linaro Limited
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier:     BSD-3-Clause
+ */
+
+#include <stdio.h>
+#include <assert.h>
+
+#include "odp_ipfragreass_ip.h"
+#include "odp_ipfragreass_fragment.h"
+
+int fragment_ipv4_packet(odp_packet_t orig_packet, odp_packet_t *out,
+			 int *out_len)
+{
+	uint32_t orig_len = odp_packet_len(orig_packet);
+	odph_ipv4hdr_t *orig_header = odp_packet_data(orig_packet);
+	uint32_t header_len = ipv4hdr_ihl(*orig_header);
+	uint32_t bytes_remaining = orig_len - header_len;
+
+	if (bytes_remaining <= MTU)
+		return -1;
+
+	/*
+	 * The main fragmentation loop (continue until all bytes from the
+	 * original payload have been assigned to a fragment)
+	 */
+	odp_packet_t frag = orig_packet;
+	odp_packet_t rest = ODP_PACKET_INVALID;
+	uint32_t frag_len;
+	uint32_t frag_offset = 0;
+	bool first_fragment = true;
+	int fragments = 0;
+
+	while (bytes_remaining) {
+		frag_len = (bytes_remaining > MTU ? (MTU + header_len)
+						  : (bytes_remaining
+						     + header_len));
+		bytes_remaining -= (frag_len - header_len);
+		if (bytes_remaining) {
+			uint32_t split_point;
+			int split_success;
+
+			split_point = first_fragment ? (frag_len)
+						     : (frag_len - header_len);
+			split_success = odp_packet_split(&frag, split_point,
+							 &rest);
+			if (split_success < 0) {
+				fprintf(stderr,
+					"ERROR: odp_packet_split\n");
+				return -1;
+			} else if (first_fragment && split_success > 0) {
+				orig_header = odp_packet_data(frag);
+			}
+		}
+
+		/* Add a header to the packet if necessary */
+		if (first_fragment) {
+			first_fragment = false;
+		} else {
+			if (odp_packet_extend_head(&frag, header_len, NULL,
+						   NULL) < 0) {
+				fprintf(stderr,
+					"ERROR: odp_packet_extend_head\n");
+				return -1;
+			}
+			if (odp_packet_copy_from_mem(frag, 0, header_len,
+						     orig_header)) {
+				fprintf(stderr,
+					"ERROR: odp_packet_copy_from_mem\n");
+				return -1;
+			}
+		}
+
+		/* Update the header */
+		odph_ipv4hdr_t *header = odp_packet_data(frag);
+
+		ipv4hdr_set_more_fragments(header, bytes_remaining != 0);
+		header->tot_len = odp_cpu_to_be_16(frag_len);
+		ipv4hdr_set_fragment_offset_oct(header, (frag_offset / 8));
+		assert((bytes_remaining == 0) ||
+		       (odp_packet_len(frag) == (MTU + header_len)));
+		assert((bytes_remaining != 0) ||
+		       (ipv4hdr_reass_payload_len(*header) + header_len
+			== orig_len));
+		odp_packet_l3_offset_set(frag, 0);
+		header->chksum = 0;
+		odph_ipv4_csum_update(frag);
+
+		out[fragments++] = frag;
+		frag = rest;
+		frag_offset += (frag_len - header_len);
+	}
+
+	if (out_len)
+		*out_len = fragments;
+
+	return 0;
+}
diff --git a/example/ipfragreass/odp_ipfragreass_fragment.h b/example/ipfragreass/odp_ipfragreass_fragment.h
new file mode 100644
index 00000000..8e32cca3
--- /dev/null
+++ b/example/ipfragreass/odp_ipfragreass_fragment.h
@@ -0,0 +1,28 @@ 
+/* Copyright (c) 2017, Linaro Limited
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier:     BSD-3-Clause
+ */
+
+#ifndef ODP_FRAGREASS_PP_FRAG_H_
+#define ODP_FRAGREASS_PP_FRAG_H_
+
+#include <odp/helper/ip.h>
+
+#define MTU 1480 /**< IPv4 payload MTU */
+
+ODP_STATIC_ASSERT(!(MTU % 8), "ODPFRAG_MTU__SIZE_ERROR");
+
+/**
+ * Break apart a larger-than-MTU packet into smaller IPv4 fragments
+ *
+ * @param      orig_packet The larger-than-MTU packet to fragment
+ * @param[out] out	   The buffer to write fragments out to
+ * @param[out] out_len	   The number of fragments produced
+ *
+ * @return 0 on success, -1 otherwise
+ */
+int fragment_ipv4_packet(odp_packet_t orig_packet, odp_packet_t *out,
+			 int *out_len);
+
+#endif
diff --git a/example/ipfragreass/odp_ipfragreass_helpers.c b/example/ipfragreass/odp_ipfragreass_helpers.c
new file mode 100644
index 00000000..bf0b20b4
--- /dev/null
+++ b/example/ipfragreass/odp_ipfragreass_helpers.c
@@ -0,0 +1,121 @@ 
+/* Copyright (c) 2017, Linaro Limited
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier:	 BSD-3-Clause
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <assert.h>
+#include <arpa/inet.h>
+
+#include "odp_ipfragreass_helpers.h"
+#include "odp_ipfragreass_ip.h"
+
+#define IP_SRC_ADDR 0xC0A80001 /* 192.168.0.1 */
+#define IP_DST_ADDR 0xC0A80002 /* 192.168.0.2 */
+
+odp_packet_t pack_udp_ipv4_packet(odp_pool_t pool, odp_u16be_t ip_id,
+				  uint32_t max_size, uint32_t min_size)
+{
+	odp_packet_t result;
+	unsigned char *buffer;
+	odph_ipv4hdr_t *header;
+	uint32_t size;
+	uint32_t header_len;
+	uint32_t header_len_words;
+
+	size = (rand() % (max_size - min_size)) + min_size;
+	result = odp_packet_alloc(pool, size);
+	if (result == ODP_PACKET_INVALID)
+		return ODP_PACKET_INVALID;
+	odp_packet_ts_set(result, odp_time_global());
+
+	/* Set the IPv4 header */
+	header_len_words = (rand() % (IP_IHL_MAX - IP_IHL_MIN + 1));
+	header_len_words += IP_IHL_MIN;
+	header_len = WORDS_TO_BYTES(header_len_words);
+	assert(header_len >= IP_HDR_LEN_MIN && header_len <= IP_HDR_LEN_MAX);
+	odp_packet_l3_offset_set(result, 0);
+	odp_packet_has_ipv4_set(result, 1);
+	buffer = odp_packet_data(result);
+	header = (odph_ipv4hdr_t *)buffer;
+	ipv4hdr_init(header);
+	header->id = odp_cpu_to_be_16(ip_id);
+	header->proto = ODPH_IPPROTO_UDP;
+	header->src_addr = odp_cpu_to_be_32(IP_SRC_ADDR);
+	header->dst_addr = odp_cpu_to_be_32(IP_DST_ADDR);
+	ipv4hdr_set_ihl_words(header, header_len_words);
+	ipv4hdr_set_payload_len(header, size - header_len);
+	header->chksum = 0;
+	odph_ipv4_csum_update(result);
+
+	/* Set the payload */
+	{
+		uint32_t i;
+		uint32_t bytes_remaining;
+		uint32_t payload_offset = header_len;
+		unsigned char seed = rand() % (UINT8_MAX + 1);
+
+		odp_packet_l4_offset_set(result, payload_offset);
+		size -= payload_offset;
+		for (i = 0; i < size; ++i) {
+			uint32_t j;
+
+			buffer = odp_packet_offset(result,
+						   payload_offset + i,
+						   &bytes_remaining,
+						   NULL);
+			for (j = 0; i < size && j < bytes_remaining; ++j, ++i)
+				buffer[j] = (unsigned char)(seed + i);
+		}
+	}
+
+	return result;
+}
+
+void shuffle(odp_packet_t *packets, int num_packets)
+{
+	int i;
+
+	if (num_packets <= 1)
+		return;
+
+	for (i = 0; i < num_packets; ++i) {
+		odp_packet_t tmp = packets[i];
+		int j = rand() % num_packets;
+
+		packets[i] = packets[j];
+		packets[j] = tmp;
+	}
+}
+
+int packet_memcmp(odp_packet_t a, odp_packet_t b, uint32_t offset_a,
+		  uint32_t offset_b, uint32_t length)
+{
+	uint32_t i = 0;
+	void *data_a, *data_b;
+
+	while (i < length) {
+		int status;
+		uint32_t bytes_remaining_a;
+		uint32_t bytes_remaining_b;
+		uint32_t bytes_remaining;
+
+		data_a = odp_packet_offset(a, offset_a + i, &bytes_remaining_a,
+					   NULL);
+		data_b = odp_packet_offset(b, offset_b + i, &bytes_remaining_b,
+					   NULL);
+		bytes_remaining = min(bytes_remaining_a, bytes_remaining_b);
+		bytes_remaining = min(bytes_remaining, length - i);
+		assert(bytes_remaining != 0 && data_a && data_b);
+
+		status = memcmp(data_a, data_b, bytes_remaining);
+		if (status != 0)
+			return status;
+		i += bytes_remaining;
+	}
+
+	return 0;
+}
diff --git a/example/ipfragreass/odp_ipfragreass_helpers.h b/example/ipfragreass/odp_ipfragreass_helpers.h
new file mode 100644
index 00000000..b6633a2c
--- /dev/null
+++ b/example/ipfragreass/odp_ipfragreass_helpers.h
@@ -0,0 +1,129 @@ 
+/* Copyright (c) 2017, Linaro Limited
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier:     BSD-3-Clause
+ */
+
+#ifndef ODP_FRAGREASS_PP_HELPERS_H_
+#define ODP_FRAGREASS_PP_HELPERS_H_
+
+#include <odp/helper/ip.h>
+
+#include "odp_ipfragreass_atomics.h"
+
+/**
+ * Generate a random IPv4 UDP packet from the specified parameters
+ *
+ * @param pool     The pool used to allocate the packet
+ * @param ip_id    The IP ID of the packet to be generated
+ * @param max_size The maximum size of the generated packet
+ * @param min_size The minimum size of the generated packet
+ *
+ * @return A handle to the generated packet
+ */
+odp_packet_t pack_udp_ipv4_packet(odp_pool_t pool, odp_u16be_t ip_id,
+				  uint32_t max_size, uint32_t min_size);
+
+/**
+ * Roughly perform a random shuffle on an array of packets
+ *
+ * @param packets     A pointer to the packets to shuffle
+ * @param num_packets The number of packets in the array
+ */
+void shuffle(odp_packet_t *packets, int num_packets);
+
+/**
+ * Compare the contents of two packets
+ *
+ * @param a	   The first packet to compare
+ * @param b	   The second packet to compare
+ * @param offset_a The offset in the first packet to begin comparing at
+ * @param offset_b The offset in the second packet to begin comparing at
+ * @param length   The number of bytes to compare
+ *
+ * @return Returns the same values as memcmp (0 if both packets are equal)
+ */
+int packet_memcmp(odp_packet_t a, odp_packet_t b, uint32_t offset_a,
+		  uint32_t offset_b, uint32_t length);
+
+/**
+ * Get the smallest of two uint32_t values
+ *
+ * @param a The first value
+ * @param b The second value
+ *
+ * @return The smallest of the two input values
+ */
+static inline uint32_t min(uint32_t a, uint32_t b)
+{
+	return a < b ? a : b;
+}
+
+/**
+ * Get the largest of two uint32_t values
+ *
+ * @param a The first value
+ * @param b The second value
+ *
+ * @return The largest of the two input values
+ */
+static inline uint32_t max(uint32_t a, uint32_t b)
+{
+	return a > b ? a : b;
+}
+
+#if __SIZEOF_PTRDIFF_T__ == 4
+/**
+ * A wrapper function to perform a 64-bit "strong" atomic compare and swap
+ * (CAS) operation. This exists to accommodate a lockless, dependency-free
+ * 64-bit CAS implementation on ARM platforms.
+ *
+ * @param var		The location at which the CAS should take place
+ * @param exp		A pointer to the expected value
+ * @param neu		A pointer to the new value to be written on success
+ * @param mo_success	The memory order on success
+ * @param mo_failure	The memory order on failure
+ *
+ * @return Whether the operation succeeded
+ */
+static inline bool atomic_strong_cas_8(uint64_t *var, uint64_t *exp,
+				       uint64_t neu, int mo_success,
+				       int mo_failure)
+{
+	#if (defined(__ARM_ARCH) && __ARM_ARCH == 7)
+	return arm_atomic_strong_compare_exchange_8(var, exp, neu, mo_success,
+						    mo_failure);
+	#else
+	return __atomic_compare_exchange_8(var, exp, neu, false, mo_success,
+					   mo_failure);
+	#endif
+}
+#elif __SIZEOF_PTRDIFF_T__ == 8
+/**
+ * A wrapper function to perform a 128-bit "strong" atomic compare and swap
+ * (CAS) operation. This exists to accommodate a lockless, dependency-free
+ * 128-bit CAS implementation on ARM platforms.
+ *
+ * @param var		The location at which the CAS should take place
+ * @param exp		A pointer to the expected value
+ * @param neu		A pointer to the new value to be written on success
+ * @param mo_success	The memory order on success
+ * @param mo_failure	The memory order on failure
+ *
+ * @return Whether the operation succeeded
+ */
+static inline bool atomic_strong_cas_16(__int128 *var, __int128 *exp,
+					__int128 neu, int mo_success,
+					int mo_failure)
+{
+	#if defined(__aarch64__)
+	return arm_atomic_strong_compare_exchange_16(var, exp, neu, mo_success,
+						     mo_failure);
+	#else
+	return __atomic_compare_exchange_n(var, exp, neu, false, mo_success,
+					   mo_failure);
+	#endif
+}
+#endif
+
+#endif
diff --git a/example/ipfragreass/odp_ipfragreass_ip.h b/example/ipfragreass/odp_ipfragreass_ip.h
new file mode 100644
index 00000000..e7281e5a
--- /dev/null
+++ b/example/ipfragreass/odp_ipfragreass_ip.h
@@ -0,0 +1,251 @@ 
+/* Copyright (c) 2017, Linaro Limited
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier:	 BSD-3-Clause
+ */
+
+#ifndef ODP_FRAGREASS_PP_IP_H_
+#define ODP_FRAGREASS_PP_IP_H_
+
+#include <odp/helper/ip.h>
+
+#define IP_HDR_LEN_MIN	ODPH_IPV4HDR_LEN
+#define IP_HDR_LEN_MAX	60
+#define IP_IHL_MIN	ODPH_IPV4HDR_IHL_MIN
+#define IP_IHL_MAX	15
+#define IP_OCTET_MAX	((1U << 14U) - 1U) /* 65535 bytes, 8192 octs, 14 bits */
+#define IP_FRAGOFF_MAX	8192 /* 13 bits */
+
+#define IP_FRAG_RESV 0x8000 /**< "Reserved" fragment flag (must be zero) */
+#define IP_FRAG_DONT 0x4000 /**< "Don't Fragment" (DF) fragment flag */
+#define IP_FRAG_MORE 0x2000 /**< "More Fragments" (MF) fragment flag */
+#define IP_FRAG_MASK 0x1fff /**< "Fragment Offset" mask */
+
+#define BYTES_TO_OCTS(bytes)	(((bytes) + 7U) / 8U)
+#define OCTS_TO_BYTES(bytes)	((bytes) * 8)
+#define WORDS_TO_BYTES(words)	((words) * 4)
+
+/**
+ * Initialise an IPv4 header structure
+ *
+ * @param h A pointer to the header structure to initialise
+ */
+static inline void ipv4hdr_init(odph_ipv4hdr_t *h)
+{
+	h->ver_ihl     = 0x45; /* IHL of 5, Version of 4 [0x45 = 0100 0101] */
+	h->tos         = 0;
+	h->tot_len     = odp_cpu_to_be_16(IP_HDR_LEN_MIN);
+	h->frag_offset = 0;
+	h->ttl         = UINT8_MAX;
+	h->chksum      = 0;
+}
+
+/**
+ * Get the Internet Header Length (IHL) of an IPv4 header in words
+ *
+ * @param h The header to get the IHL of
+ *
+ * @return The IHL of "h" in words
+ */
+static inline uint8_t ipv4hdr_ihl_words(odph_ipv4hdr_t h)
+{
+	return ODPH_IPV4HDR_IHL(h.ver_ihl);
+}
+
+/**
+ * Get the Internet Header Length (IHL) of an IPv4 header in bytes
+ *
+ * @param h The header to get the IHL of
+ *
+ * @return The IHL of "h" in bytes
+ */
+static inline uint8_t ipv4hdr_ihl(odph_ipv4hdr_t h)
+{
+	return WORDS_TO_BYTES(ipv4hdr_ihl_words(h));
+}
+
+/**
+ * Set the Internet Header Length (IHL) of an IPv4 header in words
+ *
+ * @param h   A pointer to the header to set the IHL of
+ * @param ihl The new IHL in words
+ */
+static inline void ipv4hdr_set_ihl_words(odph_ipv4hdr_t *h, uint8_t ihl)
+{
+	h->ver_ihl = (ODPH_IPV4HDR_VER(h->ver_ihl) << 4)
+		     | ODPH_IPV4HDR_IHL(ihl);
+}
+
+/**
+ * Check whether the "Don't Fragment" (DF) flag is set in an IPv4 header
+ *
+ * @param h The header to check the DF flag of
+ *
+ * @return Whether the DF flag is set
+ */
+static inline bool ipv4hdr_dont_fragment(odph_ipv4hdr_t h)
+{
+	return (h.frag_offset & odp_cpu_to_be_16(IP_FRAG_DONT));
+}
+
+/**
+ * Set the "Don't Fragment" (DF) flag of an IPv4 header
+ *
+ * @param h  A pointer to the header to set the DF of
+ * @param df Whether the DF flag should be set or unset
+ */
+static inline void ipv4hdr_set_dont_fragment(odph_ipv4hdr_t *h, bool df)
+{
+	if (df)
+		h->frag_offset |=  odp_cpu_to_be_16(IP_FRAG_DONT);
+	else
+		h->frag_offset &= ~odp_cpu_to_be_16(IP_FRAG_DONT);
+}
+
+/**
+ * Check whether the "More Fragments" (MF) flag is set in an IPv4 header
+ *
+ * @param h The header to check the MF flag of
+ *
+ * @return Whether the MF flag is set
+ */
+static inline bool ipv4hdr_more_fragments(odph_ipv4hdr_t h)
+{
+	return (h.frag_offset & odp_cpu_to_be_16(IP_FRAG_MORE));
+}
+
+/**
+ * Set the "More Fragments" (MF) flag of an IPv4 header
+ *
+ * @param h  A pointer to the header to set the MF of
+ * @param mf Whether the MF flag should be set or unset
+ */
+static inline void ipv4hdr_set_more_fragments(odph_ipv4hdr_t *h, bool mf)
+{
+	if (mf)
+		h->frag_offset |=  odp_cpu_to_be_16(IP_FRAG_MORE);
+	else
+		h->frag_offset &= ~odp_cpu_to_be_16(IP_FRAG_MORE);
+}
+
+/**
+ * Check whether an IPv4 header represents an IPv4 fragment or not
+ *
+ * @param h The header to check
+ *
+ * @return Whether "h" is the header of an IPv4 fragment or not
+ */
+static inline bool ipv4hdr_is_fragment(odph_ipv4hdr_t h)
+{
+	return (h.frag_offset & odp_cpu_to_be_16(IP_FRAG_MORE | IP_FRAG_MASK));
+}
+
+/**
+ * Get the fragment offset of an IPv4 header in octets
+ *
+ * @param h The header to get the fragment offset of
+ *
+ * @return The fragment offset of "h" in octets
+ */
+static inline uint16_t ipv4hdr_fragment_offset_oct(odph_ipv4hdr_t h)
+{
+	return (odp_be_to_cpu_16(h.frag_offset) & IP_FRAG_MASK);
+}
+
+/**
+ * Set the fragment offset of an IPv4 header in octets
+ *
+ * @param h	 A pointer to the header to set the fragment offset of
+ * @param offset The new fragment offset in octets
+ */
+static inline void ipv4hdr_set_fragment_offset_oct(odph_ipv4hdr_t *h,
+						   uint16_t offset)
+{
+	h->frag_offset = odp_cpu_to_be_16((odp_be_to_cpu_16(h->frag_offset)
+					   & ~IP_FRAG_MASK) | offset);
+}
+
+/**
+ * Get the payload length of an IPv4 header in bytes
+ *
+ * @param h The header to get the payload length of
+ *
+ * @return The payload length of "h" in bytes
+ */
+static inline uint16_t ipv4hdr_payload_len(odph_ipv4hdr_t h)
+{
+	uint32_t packet_len  = odp_be_to_cpu_16(h.tot_len);
+	uint32_t header_size = ipv4hdr_ihl(h);
+
+	return (uint16_t)(packet_len >= header_size ? (packet_len - header_size)
+						    : 0);
+}
+
+/**
+ * Get the payload length of an IPv4 header in octets
+ *
+ * @param h The header to get the payload length of
+ *
+ * @return The payload length of "h" in octets
+ */
+static inline uint16_t ipv4hdr_payload_len_oct(odph_ipv4hdr_t h)
+{
+	return BYTES_TO_OCTS(ipv4hdr_payload_len(h));
+}
+
+/**
+ * Set the payload length of an IPv4 header in bytes
+ *
+ * @param h   A pointer to the header to set the payload length of
+ * @param len The new payload length in bytes
+ */
+static inline void ipv4hdr_set_payload_len(odph_ipv4hdr_t *h, uint16_t len)
+{
+	h->tot_len = odp_cpu_to_be_16(len + ipv4hdr_ihl(*h));
+}
+
+/**
+ * Get the upper bound length in bytes of the reassembled payload that this
+ * fragment contributes to from an IPv4 header
+ *
+ * If this is called with the final fragment in a series, the exact length of
+ * the reassembled payload is computed. Otherwise, UINT16_MAX is returned.
+ *
+ * @param h The header to get the reassembled payload length from
+ *
+ * @return The upper bound for the reassembled payload length of "h" in bytes
+ */
+static inline uint16_t ipv4hdr_reass_payload_len(odph_ipv4hdr_t h)
+{
+	uint16_t fragment_offset_oct;
+
+	if (ipv4hdr_more_fragments(h))
+		return UINT16_MAX;
+
+	fragment_offset_oct = ipv4hdr_fragment_offset_oct(h);
+	return OCTS_TO_BYTES(fragment_offset_oct) + ipv4hdr_payload_len(h);
+}
+
+/**
+ * Get the upper bound length in octets of the reassembled payload that this
+ * fragment contributes to from an IPv4 header
+ *
+ * If this is called with the final fragment in a series, the exact length of
+ * the reassembled payload is computed. Otherwise, IP_OCTET_MAX is returned.
+ *
+ * @param h The header to estimate the reassembled payload length from
+ *
+ * @return The estimate for the reassembled payload length of "h" in octets
+ */
+static inline uint16_t ipv4hdr_reass_payload_len_oct(odph_ipv4hdr_t h)
+{
+	uint16_t fragment_offset_oct;
+
+	if (ipv4hdr_more_fragments(h))
+		return IP_OCTET_MAX;
+
+	fragment_offset_oct = ipv4hdr_fragment_offset_oct(h);
+	return fragment_offset_oct + ipv4hdr_payload_len_oct(h);
+}
+
+#endif
diff --git a/example/ipfragreass/odp_ipfragreass_reassemble.c b/example/ipfragreass/odp_ipfragreass_reassemble.c
new file mode 100644
index 00000000..91fadfc5
--- /dev/null
+++ b/example/ipfragreass/odp_ipfragreass_reassemble.c
@@ -0,0 +1,772 @@ 
+/* Copyright (c) 2017, Linaro Limited
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier:	 BSD-3-Clause
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+
+#include "odp_ipfragreass_reassemble.h"
+#include "odp_ipfragreass_helpers.h"
+
+#define ROT(x, k) (((x) << (k)) | ((x) >> (32 - (k))))
+
+/**
+ * Check whether two packets have the same flow (src/dst/id/proto)
+ *
+ * @param current The first packet to compare
+ * @param frag    The second packet to compare
+ *
+ * @return true if the flows match, false otherwise
+ */
+static inline bool equal_flow(struct packet *current, struct packet *frag)
+{
+	odph_ipv4hdr_t *curr_h = odp_packet_data(current->handle);
+	odph_ipv4hdr_t *frag_h = odp_packet_data(frag->handle);
+
+	return (memcmp(&curr_h->src_addr, &frag_h->src_addr,
+		       sizeof(curr_h->src_addr) + sizeof(curr_h->dst_addr))
+			      == 0 &&
+		curr_h->id    == frag_h->id &&
+		curr_h->proto == frag_h->proto);
+}
+
+/**
+ * Check whether one packet has a "later" flow than another
+ *
+ * @param current The first packet to compare
+ * @param frag    The second packet to compare
+ *
+ * @return true if the first packet's flow is later, false otherwise
+ */
+static inline bool later_flow(struct packet *current, struct packet *frag)
+{
+	odph_ipv4hdr_t *curr_h = odp_packet_data(current->handle);
+	odph_ipv4hdr_t *frag_h = odp_packet_data(frag->handle);
+
+	return (memcmp(&curr_h->src_addr, &frag_h->src_addr,
+		       sizeof(curr_h->src_addr) + sizeof(curr_h->dst_addr))
+			      > 0 ||
+		curr_h->id    > frag_h->id ||
+		curr_h->proto > frag_h->proto);
+}
+
+/**
+ * Find the earliest of two fraglist timestamps, considering a "now" timestamp
+ *
+ * @param a   The first timestamp
+ * @param b   The second timestamp
+ * @param now A timestamp indication of the time "now"
+ *
+ * @return The earliest of the first and second timestamps
+ */
+static inline struct flts earliest(struct flts a, struct flts b,
+				   struct flts now)
+{
+	struct flts result;
+	struct flts elapsed_a;
+	struct flts elapsed_b;
+
+	now.t += TS_NOW_TOLERANCE;
+	elapsed_a.t = now.t - a.t;
+	elapsed_b.t = now.t - b.t;
+	result.t = now.t - max(elapsed_a.t, elapsed_b.t);
+	return result;
+}
+
+/**
+ * Hash the flow information within an IPv4 header
+ *
+ * @param hdr A pointer to the header to hash
+ *
+ * @return A hash of the src/dst/id/proto information in the header
+ */
+static inline uint32_t hash(odph_ipv4hdr_t *hdr)
+{
+	uint32_t a = hdr->src_addr;
+	uint32_t b = hdr->dst_addr;
+	uint32_t c = hdr->id << 16 | hdr->proto;
+
+	/* A degenerate 3x32-bit Jenkins hash */
+	c ^= b;
+	c -= ROT(b, 14);
+	a ^= c;
+	a -= ROT(c, 11);
+	b ^= a;
+	b -= ROT(a, 25);
+	c ^= b;
+	c -= ROT(b, 16);
+	a ^= c;
+	a -= ROT(c,  4);
+	b ^= a;
+	b -= ROT(a, 14);
+	c ^= b;
+	c -= ROT(b, 24);
+	return c;
+}
+
+/**
+ * Check whether one fragment is "later" than another, considering a timestamp
+ * of "now"
+ *
+ * This definition of "later" relies firstly on flow, then on the endpoint of
+ * the fragment, then on the fragment offset, then on arrival time.
+ *
+ * @param a   The first fragment to compare
+ * @param b   The second fragment to compare
+ * @param now A timestamp indication of the time "now"
+ *
+ * @return Whether the first fragment is "later" than the second
+ */
+static inline bool later_fragment(struct packet *a, struct packet *b,
+				  struct flts now)
+{
+	odph_ipv4hdr_t hdr_a = *(odph_ipv4hdr_t *)odp_packet_data(a->handle);
+	odph_ipv4hdr_t hdr_b = *(odph_ipv4hdr_t *)odp_packet_data(b->handle);
+	uint32_t offset_a = ipv4hdr_fragment_offset_oct(hdr_a);
+	uint32_t offset_b = ipv4hdr_fragment_offset_oct(hdr_b);
+	uint32_t payload_len_a = ipv4hdr_payload_len(hdr_a);
+	uint32_t payload_len_b = ipv4hdr_payload_len(hdr_b);
+	uint32_t endpoint_a = OCTS_TO_BYTES(offset_a) + payload_len_a;
+	uint32_t endpoint_b = OCTS_TO_BYTES(offset_b) + payload_len_b;
+
+	return later_flow(a, b) ||
+	       (equal_flow(a, b) &&
+			((endpoint_a > endpoint_b) ||
+			((endpoint_a == endpoint_b) &&
+				((offset_a < offset_b) ||
+				(((offset_a == offset_b)) &&
+					(b->arrival.t == earliest(a->arrival,
+								  b->arrival,
+								  now).t))))));
+}
+
+/**
+ * Attempt to extract a whole packet from a list of sorted fragments
+ *
+ * If a complete packet is formed, its tail pointer is returned, and the tail
+ * pointer for the remaining packets is written out to remaining_packets.
+ *
+ * @param[in]  tail		 The tail of the list of fragments to parse
+ * @param[out] remaining_packets The pointer to any remaining packets
+ * @param[out] made_changes	 Whether any changes were made to the fragments
+ *
+ * @return The tail pointer of any reassembled packet, or NULL otherwise
+ */
+static struct packet *extract_complete_packet(struct packet *tail,
+					      struct packet **remaining_packets,
+					      int *made_changes)
+{
+	/*
+	 * Iterate through the flows in this fragment list (until a packet is
+	 * reassembled).
+	 */
+	 while (tail) {
+		/*
+		 * Work backwards through the fragments in a single flow,
+		 * attempting to glue together a whole packet. Upon finding a
+		 * discontinuity, break out of the loop for this flow and try
+		 * the next (if there is one).
+		 */
+		struct packet *current = tail;
+		odph_ipv4hdr_t tail_hdr;
+		uint16_t final_frag_offset;
+		uint16_t expected_frag_offset;
+
+		tail_hdr = *(odph_ipv4hdr_t *)odp_packet_data(tail->handle);
+		final_frag_offset = ipv4hdr_fragment_offset_oct(tail_hdr);
+		expected_frag_offset = final_frag_offset;
+		while (current) {
+			odph_ipv4hdr_t curr_hdr;
+			uint16_t curr_offset_oct;
+			bool final_fragment;
+			struct packet *prev;
+			void *tmp;
+
+			prev = prev_packet(*current);
+			tmp = odp_packet_data(current->handle);
+			curr_hdr = *(odph_ipv4hdr_t *)tmp;
+			curr_offset_oct = ipv4hdr_fragment_offset_oct(curr_hdr);
+			final_fragment = (curr_offset_oct == final_frag_offset);
+
+			/*
+			 * If the final fragment in the chain has "More
+			 * Fragments" set, it's not the final packet of the
+			 * datagram as a whole.
+			 */
+			if (final_fragment && ipv4hdr_more_fragments(curr_hdr))
+				break;
+
+			/*
+			 * If this is the first fragment in a chain, we may have
+			 * completed the reassembly of a whole packet.
+			 */
+			if (prev == NULL || !equal_flow(current, prev)) {
+				if (curr_offset_oct)
+					break;
+
+				/*
+				 * Extract the complete packet from the list of
+				 * remaining packets
+				 */
+				if (remaining_packets)
+					*remaining_packets = prev;
+				set_prev_packet(current, NULL);
+				if (made_changes)
+					*made_changes = 1;
+				return tail;
+			}
+
+			/*
+			 * Fragments should be consistent with those previously
+			 * processed
+			 */
+			odph_ipv4hdr_t prev_hdr;
+			uint16_t prev_off_oct;
+			uint16_t prev_oct;
+
+			tmp = odp_packet_data(prev->handle);
+			prev_hdr = *(odph_ipv4hdr_t *)tmp;
+			prev_off_oct = ipv4hdr_fragment_offset_oct(prev_hdr);
+			prev_oct = BYTES_TO_OCTS(ipv4hdr_payload_len(prev_hdr));
+			if (curr_offset_oct != prev_off_oct + prev_oct) {
+				if (prev_off_oct + prev_oct < curr_offset_oct) {
+					/*
+					 * If there's no overlap, this is just a
+					 * regular discontinuity
+					 */
+					break;
+				}
+
+				/*
+				 * Fragment duplication or overlap has occurred!
+				 * We don't handle such occurrences in this
+				 * simple example application.
+				 */
+				assert(0);
+				break;
+			}
+
+			expected_frag_offset -= prev_oct;
+			current = prev;
+		}
+
+		/*
+		 * Since we haven't had any luck finding a whole packet within
+		 * this flow, let's try to look at other flows in this fraglist
+		 * (if there are any others). */
+		if (current) {
+			while (prev_packet(*current) &&
+			       equal_flow(current, prev_packet(*current))) {
+				current = prev_packet(*current);
+			}
+
+			tail = prev_packet(*current);
+			remaining_packets = prev_packet_ptr(current);
+		} else {
+			tail = NULL;
+		}
+	}
+
+	return NULL;
+}
+
+/*
+ * Glue together a list of fragments sorted by fragment offset, writing the
+ * result to an output queue
+ *
+ * @param tail The tail pointer to the list of fragments to reassemble
+ * @param out  The output queue to write the result to
+ *
+ * @return 0 on success, -1 otherwise
+ */
+static int send_packet(struct packet *tail, odp_queue_t out)
+{
+	struct packet result = *tail;
+	struct packet *current = prev_packet(result);
+
+	/*
+	 * Reassemble the complete packet (working backwards from the last
+	 * fragment)
+	 */
+	while (current && equal_flow(current, &result)) {
+		struct packet new_result = *current;
+		odph_ipv4hdr_t *header;
+		int concat_success;
+
+		current = prev_packet(new_result);
+		header = odp_packet_data(result.handle);
+		odp_packet_pull_head(result.handle, ipv4hdr_ihl(*header));
+		concat_success = odp_packet_concat(&new_result.handle,
+						   result.handle);
+		if (concat_success < 0) {
+			fprintf(stderr, "ERROR: odp_packet_concat\n");
+			return -1;
+		}
+		result = new_result;
+	}
+
+	/* Fix the header */
+	{
+		odph_ipv4hdr_t *header = odp_packet_data(result.handle);
+		uint32_t length = odp_packet_len(result.handle);
+
+		assert(length >= IP_HDR_LEN_MIN || length <= UINT16_MAX);
+		header->tot_len = odp_cpu_to_be_16(length);
+		ipv4hdr_set_more_fragments(header, 0);
+		ipv4hdr_set_fragment_offset_oct(header, 0);
+		header->chksum = 0;
+		odph_ipv4_csum_update(result.handle);
+	}
+
+	assert(odp_queue_enq(out, odp_packet_to_event(result.handle)) >= 0);
+	return 0;
+}
+
+/**
+ * Sort a fraglist using the "later_fragment" function
+ *
+ * @param fl  A pointer to the fraglist to sort
+ * @param now A timestamp indication of the time "now"
+ */
+static void sort_fraglist(union fraglist *fl, struct flts now)
+{
+	struct packet *current = fl->tail;
+
+	fl->tail = NULL;
+	while (current) {
+		struct packet *to_insert = current;
+
+		current = prev_packet(*to_insert);
+		if (fl->tail == NULL ||
+		    later_fragment(to_insert, fl->tail, now)) {
+			set_prev_packet(to_insert, fl->tail);
+			fl->tail = to_insert;
+		} else {
+			struct packet *current = fl->tail;
+
+			while (prev_packet(*current) &&
+			       later_fragment(prev_packet(*current), to_insert,
+					      now)) {
+				current = prev_packet(*current);
+			}
+			set_prev_packet(to_insert, prev_packet(*current));
+			set_prev_packet(current, to_insert);
+		}
+	}
+}
+
+/**
+ * Add a thread local fraglist to a shared fraglist
+ *
+ * @param fl		Pointer to the shared fraglist to add "frags" to
+ * @param frags		The thread local fraglist to add to "fl"
+ * @param frags_head	Pointer to the head fragment of "frags"
+ * @param now		A timestamp indication of the time "now"
+ * @param out		The queue to which reassembled packets should be written
+ * @param dont_assemble	Whether reassembly should be attempted by default
+ *
+ * @return The number of packets reassembled and sent to the output queue
+ */
+static int add_fraglist_to_fraglist(union fraglist *fl, union fraglist frags,
+				    struct packet *frags_head, struct flts now,
+				    odp_queue_t out, bool dont_assemble)
+{
+	int reassembled = 0;
+
+redo:;
+	union fraglist oldfl;
+	union fraglist newfl;
+	struct flts oldfl_earliest;
+	struct flts frags_earliest;
+
+	__atomic_load(&fl->half[0], &oldfl.half[0], __ATOMIC_RELAXED);
+	__atomic_load(&fl->half[1], &oldfl.half[1], __ATOMIC_RELAXED);
+
+	/*
+	 * If we're updating a non-empty fraglist, we should always attempt
+	 * reassembly!
+	 */
+	if (oldfl.tail != NULL)
+		dont_assemble = false;
+
+	/* Insert the new fragment(s) to the tail of the fraglist */
+	set_prev_packet(frags_head, oldfl.tail);
+	newfl.tail = frags.tail;
+
+	/*
+	 * Update the fraglist variables (accumulating the length of the
+	 * received pieces into "part_len", and updating the perceived 'true'
+	 * length of the whole packet along with the timestamp of the earliest
+	 * fragment in this list).
+	 */
+	oldfl_earliest.t = oldfl.earliest;
+	frags_earliest.t = frags.earliest;
+	newfl.part_len  = min(IP_OCTET_MAX, oldfl.part_len + frags.part_len);
+	newfl.whole_len = min(oldfl.whole_len, frags.whole_len);
+	newfl.earliest  = (oldfl.tail == NULL ? frags.earliest
+					      : earliest(oldfl_earliest,
+							 frags_earliest,
+							 now).t);
+
+	/*
+	 * Check if it looks like we have all the fragments for a whole packet
+	 * yet. If not, just write out our changes and move on.
+	 */
+	if (newfl.part_len < newfl.whole_len || dont_assemble) {
+#if __SIZEOF_PTRDIFF_T__ == 4
+		if (!atomic_strong_cas_8(&fl->raw, &oldfl.raw, newfl.raw,
+					 __ATOMIC_RELEASE, __ATOMIC_RELAXED)) {
+#elif __SIZEOF_PTRDIFF_T__ == 8
+		if (!atomic_strong_cas_16(&fl->raw, &oldfl.raw, newfl.raw,
+					  __ATOMIC_RELEASE, __ATOMIC_RELAXED)) {
+#endif
+			set_prev_packet(frags_head, NULL);
+			goto redo;
+		}
+		return reassembled;
+	}
+
+	/*
+	 * It /appears/ that we have all the fragments for a packet. Things are
+	 * not always as they appear, however, particularly in the case of a
+	 * hash map collision where part_len and whole_len may be incorrect
+	 * (and, hence, must be verified).
+	 *
+	 * Take exclusive ownership over this fraglist while we attempt
+	 * reassembly. If we're truly done with it, then this releases the slot,
+	 * otherwise we'll update the slot with our changes later.
+	 */
+	 {
+		union fraglist nullfl;
+
+		init_fraglist(&nullfl);
+#if __SIZEOF_PTRDIFF_T__ == 4
+		if (!atomic_strong_cas_8(&fl->raw, &oldfl.raw, nullfl.raw,
+					 __ATOMIC_ACQUIRE, __ATOMIC_RELAXED)) {
+#elif __SIZEOF_PTRDIFF_T__ == 8
+		if (!atomic_strong_cas_16(&fl->raw, &oldfl.raw, nullfl.raw,
+					  __ATOMIC_ACQUIRE, __ATOMIC_RELAXED)) {
+#endif
+			set_prev_packet(frags_head, NULL);
+			goto redo;
+		}
+	}
+
+	/*
+	 * Find any complete packets within the fraglist, cut them out of the
+	 * list, and send them to the output queue. Note that there may be
+	 * several complete packets, as we may have added multiple new fragments
+	 * into the fraglist.
+	 */
+	struct packet *remaining_packets;
+	struct packet *complete_datagram;
+	int fraglist_changed = 0;
+	int call_changed_fraglist = 0;
+
+	sort_fraglist(&newfl, now);
+	remaining_packets = newfl.tail;
+	dont_assemble = 1;
+	while ((complete_datagram =
+		extract_complete_packet(remaining_packets,
+					&remaining_packets,
+					&call_changed_fraglist)) ||
+		call_changed_fraglist) {
+		fraglist_changed = 1;
+		if (complete_datagram) {
+			assert(!send_packet(complete_datagram, out));
+			++reassembled;
+			dont_assemble = 0;
+		}
+		call_changed_fraglist = 0;
+	}
+
+	/*
+	 * If there are still fragments in this fraglist, we have changes to
+	 * write back.
+	 */
+	if (remaining_packets != NULL) {
+		union fraglist update;
+
+		update.tail      = remaining_packets;
+		update.part_len  = newfl.part_len;
+		update.whole_len = newfl.whole_len;
+		update.earliest  = newfl.earliest;
+
+		/*
+		 * We've cut fragments from the fragment list chain, and so
+		 * should recalculate the part_len, whole_len, and earliest
+		 * variables before writing out our changes.
+		 */
+		if (fraglist_changed) {
+			struct packet *current = remaining_packets;
+
+			update.earliest = now.t;
+			while (current) {
+				odph_ipv4hdr_t *h;
+				uint16_t part_oct;
+				uint16_t whole_oct;
+				struct flts update_earliest;
+
+				update_earliest.t = update.earliest;
+				h = odp_packet_data(current->handle);
+				part_oct = ipv4hdr_payload_len_oct(*h);
+				whole_oct = ipv4hdr_reass_payload_len_oct(*h);
+				update.part_len = min(IP_OCTET_MAX,
+						      update.part_len
+						      + part_oct);
+				update.whole_len = min(update.whole_len,
+						       whole_oct);
+				update.earliest = earliest(update_earliest,
+							   current->arrival,
+							   now).t;
+				frags_head = current;
+				current = prev_packet(*current);
+			}
+			frags = update;
+			goto redo;
+		}
+
+		/*
+		 * Note that we may have to reassemble more packets, as adding
+		 * the fragments this thread has exclusive access to into the
+		 * shared fraglist may entail new packets being completed.
+		 */
+		frags = update;
+		frags_head = frags.tail;
+		while (prev_packet(*frags_head))
+			frags_head = prev_packet(*frags_head);
+		goto redo;
+	}
+
+	return reassembled;
+}
+
+/**
+ * Add a single fragment to a shared fraglist
+ *
+ * @param fl Pointer to the shared fraglist to add "frag" to
+ * @param frag Pointer to the fragment to add to "fl"
+ * @param frag_payload_len The payload length of "frag" in octets
+ * @param frag_reass_payload_len The estimated reassembled payload length of
+ *                               "frag" in octets
+ * @param out The queue to which reassembled packets should be written
+ *
+ * @return The number of packets reassembled and sent to the output
+ */
+static int add_frag_to_fraglist(union fraglist *fl, struct packet *frag,
+				uint16_t frag_payload_len,
+				uint16_t frag_reass_payload_len,
+				odp_queue_t out)
+{
+	union fraglist frags;
+
+	frags.tail = frag;
+	frags.part_len = frag_payload_len;
+	frags.whole_len = frag_reass_payload_len;
+	frags.earliest = frag->arrival.t;
+
+	return add_fraglist_to_fraglist(fl, frags, frags.tail, frag->arrival,
+					out, false);
+}
+
+/**
+ * Remove the stale flows from a shared fraglist this thread has exclusive
+ * access over
+ *
+ * @param fl	   Pointer to the shared fraglist to clean stale flows from
+ * @param oldfl	   The value of the fraglist before we took exclusive access
+ * @param time_now A timestamp indication of the time "now"
+ * @param out	   The queue to which reassembled packets should be written
+ * @param force	   Whether all flows in the fraglist should be considered stale
+ */
+static void remove_stale_flows(union fraglist *fl, union fraglist oldfl,
+			       struct flts timestamp_now, odp_queue_t out,
+			       bool force)
+{
+	union fraglist newfl = oldfl;
+	struct packet *current;
+	struct packet *current_tail;
+	struct packet *remaining_frags_head;
+	struct flts flow_earliest;
+
+	/*
+	 * Sort the fraglist so we can step through its fragments flow-by-flow
+	 */
+	sort_fraglist(&newfl, timestamp_now);
+
+	/* Remove stale flows from the fraglist */
+	current = newfl.tail;
+	current_tail = newfl.tail;
+	remaining_frags_head = NULL;
+	flow_earliest = current->arrival;
+	newfl.earliest = timestamp_now.t;
+	while (current) {
+		struct packet *prev = prev_packet(*current);
+
+		/*
+		 * If this is the first fragment in a chain, we can make the
+		 * decision on whether this flow should be kept or discarded
+		 */
+		if (prev == NULL || !equal_flow(current, prev)) {
+			struct flts elapsed;
+			uint64_t elapsed_ns;
+
+			elapsed.t = timestamp_now.t - flow_earliest.t;
+			elapsed_ns = (elapsed.t * TS_RES_NS);
+			if ((elapsed_ns >= FLOW_TIMEOUT_NS &&
+			     elapsed.t + TS_NOW_TOLERANCE >=
+			     TS_NOW_TOLERANCE) || force) {
+				struct packet *to_free = current_tail;
+
+				while (to_free != prev) {
+					struct packet *next;
+
+					next = prev_packet(*to_free);
+					odp_packet_free(to_free->handle);
+					to_free = next;
+				}
+
+				if (remaining_frags_head)
+					set_prev_packet(remaining_frags_head,
+							prev);
+				else
+					newfl.tail = prev;
+			} else {
+				odph_ipv4hdr_t *h;
+				uint16_t part_oct;
+				uint16_t whole_oct;
+				struct flts newfl_earliest;
+
+				newfl_earliest.t = newfl.earliest;
+				remaining_frags_head = current;
+				h = odp_packet_data(current->handle);
+				part_oct = ipv4hdr_payload_len_oct(*h);
+				whole_oct = ipv4hdr_reass_payload_len_oct(*h);
+				newfl.part_len = min(IP_OCTET_MAX,
+						     newfl.part_len + part_oct);
+				newfl.whole_len = min(newfl.whole_len,
+						      whole_oct);
+				newfl.earliest = earliest(newfl_earliest,
+							  flow_earliest,
+							  timestamp_now).t;
+			}
+
+			current_tail = prev;
+			flow_earliest.t = EARLIEST_MAX;
+		} else {
+			flow_earliest = earliest(flow_earliest,
+						 current->arrival,
+						 timestamp_now);
+		}
+
+		current = prev;
+	}
+
+	/*
+	 * If there are any remaining fragments, write them back into the
+	 * fraglist
+	 */
+	if (remaining_frags_head)
+		add_fraglist_to_fraglist(fl, newfl, remaining_frags_head,
+					 timestamp_now, out, false);
+}
+
+/**
+ * Clean up any stale flows within a fraglist
+ *
+ * @param fl	   Pointer to the shared fraglist to clean stale flows from
+ * @param out	   The queue to which reassembled packets should be written
+ * @param force	   Whether all flows in the fraglist should be considered stale
+ */
+static void garbage_collect_fraglist(union fraglist *fl, odp_queue_t out,
+				     bool force)
+{
+	uint64_t time_now;
+	struct flts timestamp_now;
+	struct flts elapsed;
+	uint64_t elapsed_ns;
+	union fraglist oldfl;
+
+redo:;
+	time_now = odp_time_to_ns(odp_time_global());
+	timestamp_now.t = time_now / TS_RES_NS;
+	__atomic_load(&fl->half[0], &oldfl.half[0], __ATOMIC_RELAXED);
+	__atomic_load(&fl->half[1], &oldfl.half[1], __ATOMIC_RELAXED);
+	elapsed.t = timestamp_now.t - oldfl.earliest;
+
+	if (oldfl.tail == NULL ||
+	    elapsed.t + TS_NOW_TOLERANCE < TS_NOW_TOLERANCE)
+		return;
+
+	elapsed_ns = (elapsed.t * TS_RES_NS);
+	assert(force || elapsed_ns <= 86400000000000);
+	if (elapsed_ns >= FLOW_TIMEOUT_NS || force) {
+		union fraglist nullfl;
+
+		init_fraglist(&nullfl);
+#if __SIZEOF_PTRDIFF_T__ == 4
+		if (!atomic_strong_cas_8(&fl->raw, &oldfl.raw, nullfl.raw,
+					 __ATOMIC_ACQUIRE, __ATOMIC_RELAXED)) {
+#elif __SIZEOF_PTRDIFF_T__ == 8
+		if (!atomic_strong_cas_16(&fl->raw, &oldfl.raw, nullfl.raw,
+					  __ATOMIC_ACQUIRE, __ATOMIC_RELAXED)) {
+#endif
+			goto redo;
+		}
+
+		remove_stale_flows(fl, oldfl, timestamp_now, out, force);
+	}
+}
+
+int reassemble_ipv4_packets(union fraglist *fraglists, int num_fraglists,
+			    struct packet *fragments, int num_fragments,
+			    odp_queue_t out)
+{
+	int i;
+	int packets_reassembled = 0;
+
+	for (i = 0; i < num_fragments; ++i) {
+		struct packet frag;
+		odph_ipv4hdr_t *hdr;
+		uint16_t frag_payload_len;
+		uint16_t frag_reass_payload_len;
+		int status;
+
+		frag = fragments[i];
+		hdr = odp_packet_data(frag.handle);
+		frag_payload_len = ipv4hdr_payload_len_oct(*hdr);
+		frag_reass_payload_len = ipv4hdr_reass_payload_len_oct(*hdr);
+
+		/*
+		 * Find the appropriate hash map bucket for fragments in this
+		 * flow. In the case of collisions, fragments for multiple flows
+		 * are simply stored in the same list.
+		 */
+		uint32_t key = hash(hdr);
+		union fraglist *fl = &fraglists[key % num_fraglists];
+
+		status = add_frag_to_fraglist(fl, &fragments[i],
+					      frag_payload_len,
+					      frag_reass_payload_len, out);
+		if (status < 0) {
+			fprintf(stderr,
+				"ERROR: failed to add fragment to fraglist\n");
+			return -1;
+		}
+		packets_reassembled += status;
+	}
+
+	return packets_reassembled;
+}
+
+void garbage_collect_fraglists(union fraglist *fraglists, int num_fraglists,
+			       odp_queue_t out, bool destroy_all)
+{
+	int i;
+
+	for (i = 0; i < num_fraglists; ++i)
+		garbage_collect_fraglist(&fraglists[i], out, destroy_all);
+}
diff --git a/example/ipfragreass/odp_ipfragreass_reassemble.h b/example/ipfragreass/odp_ipfragreass_reassemble.h
new file mode 100644
index 00000000..3e6c9684
--- /dev/null
+++ b/example/ipfragreass/odp_ipfragreass_reassemble.h
@@ -0,0 +1,211 @@ 
+/* Copyright (c) 2017, Linaro Limited
+ * All rights reserved.
+ *
+ * SPDX-License-Identifier:	 BSD-3-Clause
+ */
+
+#ifndef ODP_FRAGREASS_PP_REASSEMBLE_H_
+#define ODP_FRAGREASS_PP_REASSEMBLE_H_
+
+#include <odp/helper/ip.h>
+
+#include "odp_ipfragreass_ip.h"
+#include "odp_ipfragreass_helpers.h"
+
+ODP_STATIC_ASSERT((__SIZEOF_PTRDIFF_T__ == 4 || __SIZEOF_PTRDIFF_T__ == 8),
+		  "ODPREASS_PTR__SIZE_ERROR");
+
+/**
+ * The time in nanoseconds after reception of the earliest fragment that a
+ * flow of traffic is considered to be stale
+ */
+#define FLOW_TIMEOUT_NS 15000000000ULL
+
+/** Convert nanoseconds into a unit for packet.arrival */
+#if __SIZEOF_PTRDIFF_T__ == 4
+#define TS_RES_NS ((uint64_t)5000000000) /**< ns -> 5s */
+#elif __SIZEOF_PTRDIFF_T__ == 8
+#define TS_RES_NS ((uint64_t)1000000)    /**< ns -> 1ms */
+#endif
+
+/**
+ * The maximum value of the packet.arrival field.
+ */
+#if __SIZEOF_PTRDIFF_T__ == 4
+#define EARLIEST_MAX 15
+#elif __SIZEOF_PTRDIFF_T__ == 8
+#define EARLIEST_MAX UINT32_MAX
+#endif
+
+/**
+ * The time in packet.arrival ticks that indications of the time "now" are
+ * permitted to be off by.
+ */
+#if __SIZEOF_PTRDIFF_T__ == 4
+#define TS_NOW_TOLERANCE 1
+#elif __SIZEOF_PTRDIFF_T__ == 8
+#define TS_NOW_TOLERANCE 5000
+#endif
+
+/**
+ * The timestamp format used for fragments. Sadly, this has to be a structure
+ * as we may need a bit field.
+ */
+struct flts {
+#if __SIZEOF_PTRDIFF_T__ == 4
+	unsigned int t:4;
+#elif __SIZEOF_PTRDIFF_T__ == 8
+	uint32_t t;
+#endif
+};
+
+/**
+ * Metadata for reassembly, to be stored alongside each fragment
+ */
+struct packet {
+	odp_packet_t handle; /**< The ODP packet handle for this fragment  */
+	struct packet *prev; /**< Pointer to the fragment "before" this one */
+	struct flts arrival; /**< Arrival timestamp for this fragment */
+};
+
+/**
+ * A list of IP fragments associated with one or more traffic flows, along with
+ * some related data
+ *
+ * This is used as an atomically-updated hash map bucket in reassembly, and is
+ * assumed to be packed with no padding.
+ */
+union fraglist {
+	struct {
+		/**
+		 * The timestamp of the earliest arriving fragment in this
+		 * fraglist
+		 */
+#if __SIZEOF_PTRDIFF_T__ == 4
+		unsigned int earliest:4;
+#elif __SIZEOF_PTRDIFF_T__ == 8
+		uint32_t earliest;
+#endif
+
+		/**
+		 * The sum of the payloads of the fragments in this list
+		 *
+		 * That is, the size of reassembling all the fragments in this
+		 * list into one big packet (minus the header).
+		 */
+		unsigned int part_len:14;
+
+		/**
+		 * The smallest reassembled payload length upper bound from
+		 * all fragments in this list
+		 *
+		 * This is the threshold over which, given the right
+		 * circumstances, "part_len" might indicate that we are able
+		 * to reassemble a packet.
+		 */
+		unsigned int whole_len:14;
+
+		/**
+		 * The tail of a "reverse" linked list of fragments
+		 *
+		 * Each fragment element has a "prev" pointer to the element
+		 * before it in the list. When used in a multi-threaded
+		 * environment, new elements should be inserted atomically by
+		 * modifying this tail pointer.
+		 */
+		struct packet *tail;
+	};
+
+#if __SIZEOF_PTRDIFF_T__ == 4
+	struct {
+		uint32_t half[2];
+	};
+	uint64_t raw;
+#elif __SIZEOF_PTRDIFF_T__ == 8
+	struct {
+		uint64_t half[2];
+	};
+	__int128 raw;
+#endif
+};
+
+/**
+ * Initialise a fraglist structure
+ *
+ * @param fl The fraglist to initialise
+ */
+static inline void init_fraglist(union fraglist *fl)
+{
+	fl->earliest  = EARLIEST_MAX;
+	fl->part_len  = 0;
+	fl->whole_len = IP_OCTET_MAX;
+	fl->tail      = NULL;
+}
+
+/**
+ * Get the packet "before" a packet in a linked list
+ *
+ * @param packet The packet from which the previous should be located
+ *
+ * @return A pointer to the packet before the input packet (can be NULL)
+ */
+static inline struct packet *prev_packet(struct packet packet)
+{
+	return packet.prev;
+}
+
+/**
+ * Get the address of the pointer to the packet "before" a packet in a linked
+ * list
+ *
+ * @param packet The packet for which the previous pointer should be located
+ *
+ * @return A pointer to the "prev" packet pointer of the input packet
+ */
+static inline struct packet **prev_packet_ptr(struct packet *packet)
+{
+	return &packet->prev;
+}
+
+/**
+ * Set the packet "before" a packet in a linked list
+ *
+ * @param packet The packet to set the previous packet from
+ * @param prev   The packet to set as being before "packet"
+ */
+static inline void set_prev_packet(struct packet *packet, struct packet *prev)
+{
+	packet->prev = prev;
+}
+
+/**
+ * Attempt packet reassembly with the aid of a number of new fragments
+ *
+ * Add "num_fragments" fragments to a fraglist hash map (with "num_fraglist"
+ * entries), attempting reassembly and writing any successfully reassembled
+ * packets out to the "out" queue.
+ *
+ * @param fraglists	The hash map structure to add the fragments to
+ * @param num_fraglists	The number of entries in the hash map
+ * @param fragments	Pointer to the fragments to add
+ * @param num_fragments	The number of fragments to add
+ * @param out		The queue to which reassembled packets should be written
+ *
+ * @return The number of packets successfully reassembled and written to "out"
+ */
+int reassemble_ipv4_packets(union fraglist *fraglists, int num_fraglists,
+			    struct packet *fragments, int num_fragments,
+			    odp_queue_t out);
+
+/**
+ * Clean up any stale flows within a fraglist hash map
+ *
+ * @param fraglists	The hash map structure to clean flows from
+ * @param num_fraglists	The number of entries in the hash map
+ * @param out		The queue to which reassembled packets should be written
+ * @param destroy_all	Whether all encountered flows should be cleaned up
+ */
+void garbage_collect_fraglists(union fraglist *fraglists, int num_fraglists,
+			       odp_queue_t out, bool destroy_all);
+
+#endif
diff --git a/example/m4/configure.m4 b/example/m4/configure.m4
index 620db04f..18218d05 100644
--- a/example/m4/configure.m4
+++ b/example/m4/configure.m4
@@ -14,6 +14,7 @@  AC_CONFIG_FILES([example/classifier/Makefile
 		 example/generator/Makefile
 		 example/hello/Makefile
 		 example/ipsec/Makefile
+		 example/ipfragreass/Makefile
 		 example/l2fwd_simple/Makefile
 		 example/l3fwd/Makefile
 		 example/packet/Makefile