Message-ID: <B7C8BC78-4F65-4C5F-9145-C59AB0923702@fb.com>
Date:   Fri, 31 May 2019 15:56:32 +0000
From:   Song Liu <songliubraving@...com>
To:     Alan Maguire <alan.maguire@...cle.com>
CC:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "hawk@...nel.org" <hawk@...nel.org>,
        John Fastabend <john.fastabend@...il.com>,
        Networking <netdev@...r.kernel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        "xdp-newbies@...r.kernel.org" <xdp-newbies@...r.kernel.org>,
        Shuah Khan <shuah@...nel.org>, Martin Lau <kafai@...com>,
        Yonghong Song <yhs@...com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: Re: [PATCH bpf-next v4] selftests/bpf: measure RTT from xdp using
 xdping



> On May 31, 2019, at 2:24 AM, Alan Maguire <alan.maguire@...cle.com> wrote:
> 
> xdping allows us to get latency estimates from XDP.  Output looks
> like this:
> 
> ./xdping -I eth4 192.168.55.8
> Setting up XDP for eth4, please wait...
> XDP setup disrupts network connectivity, hit Ctrl+C to quit
> 
> Normal ping RTT data
> [Ignore final RTT; it is distorted by XDP using the reply]
> PING 192.168.55.8 (192.168.55.8) from 192.168.55.7 eth4: 56(84) bytes of data.
> 64 bytes from 192.168.55.8: icmp_seq=1 ttl=64 time=0.302 ms
> 64 bytes from 192.168.55.8: icmp_seq=2 ttl=64 time=0.208 ms
> 64 bytes from 192.168.55.8: icmp_seq=3 ttl=64 time=0.163 ms
> 64 bytes from 192.168.55.8: icmp_seq=8 ttl=64 time=0.275 ms
> 
> 4 packets transmitted, 4 received, 0% packet loss, time 3079ms
> rtt min/avg/max/mdev = 0.163/0.237/0.302/0.054 ms
> 
> XDP RTT data:
> 64 bytes from 192.168.55.8: icmp_seq=5 ttl=64 time=0.02808 ms
> 64 bytes from 192.168.55.8: icmp_seq=6 ttl=64 time=0.02804 ms
> 64 bytes from 192.168.55.8: icmp_seq=7 ttl=64 time=0.02815 ms
> 64 bytes from 192.168.55.8: icmp_seq=8 ttl=64 time=0.02805 ms
> 
> The xdping program loads the associated xdping_kern.o BPF program
> and attaches it to the specified interface.  If run in client
> mode (the default), it will add a map entry keyed by the
> target IP address; this map will store RTT measurements, current
> sequence number etc.  Finally in client mode the ping command
> is executed, and the xdping BPF program will use the last ICMP
> reply, reformulate it as an ICMP request with the next sequence
> number and XDP_TX it.  After the reply to that request is received
> we can measure RTT and repeat until the desired number of
> measurements is made.  This is why the sequence numbers in the
> normal ping are 1, 2, 3 and 8.  We XDP_TX a modified version
> of ICMP reply 4 and keep doing this until we get the 4 replies
> we need; hence the networking stack only sees reply 8, where
> we have XDP_PASSed it upstream since we are done.
> 
> In server mode (-s), xdping simply takes ICMP requests and replies
> to them in XDP rather than passing the request up to the networking
> stack.  No map entry is required.
> 
> xdping can be run in native XDP mode (the default, or specified
> via -N) or in skb mode (-S).
> 
> A test program test_xdping.sh exercises some of these options.
> 
> Note that native XDP does not seem to XDP_TX for veths, hence -N
> is not tested.  Looking at the code, it looks like XDP_TX is
> supported so I'm not sure if that's expected.  Running xdping in
> native mode for ixgbe as both client and server works fine.
> 
> Changes since v3
> 
> - fixed seq to be __be16 (Song Liu)
> - fixed fd checks in xdping.c (Song Liu)
> 
> Changes since v2
> 
> - updated commit message to explain why seq number of last
>  ICMP reply is 8 not 4 (Song Liu)
> - updated types of seq number, raddr and eliminated csum variable
>  in xdpclient/xdpserver functions as it was not needed (Song Liu)
> - added XDPING_DEFAULT_COUNT definition and usage specification of
>  default/max counts (Song Liu)
> 
> Changes since v1
> - moved from RFC to PATCH
> - removed unused variable in ipv4_csum() (Song Liu)
> - refactored ICMP checks into icmp_check() function called by client
>   and server programs and reworked client and server programs due
>   to lack of shared code (Song Liu)
> - added checks to ensure that SKB and native mode are not requested
>   together (Song Liu)
> 
> Signed-off-by: Alan Maguire <alan.maguire@...cle.com>
> ---
> tools/testing/selftests/bpf/.gitignore          |   1 +
> tools/testing/selftests/bpf/Makefile            |   5 +-
> tools/testing/selftests/bpf/progs/xdping_kern.c | 184 +++++++++++++++++
> tools/testing/selftests/bpf/test_xdping.sh      |  99 ++++++++++
> tools/testing/selftests/bpf/xdping.c            | 252 ++++++++++++++++++++++++
> tools/testing/selftests/bpf/xdping.h            |  13 ++
> 6 files changed, 552 insertions(+), 2 deletions(-)
> create mode 100644 tools/testing/selftests/bpf/progs/xdping_kern.c
> create mode 100755 tools/testing/selftests/bpf/test_xdping.sh
> create mode 100644 tools/testing/selftests/bpf/xdping.c
> create mode 100644 tools/testing/selftests/bpf/xdping.h
> 
> diff --git a/tools/testing/selftests/bpf/.gitignore b/tools/testing/selftests/bpf/.gitignore
> index b2a9902..7470327 100644
> --- a/tools/testing/selftests/bpf/.gitignore
> +++ b/tools/testing/selftests/bpf/.gitignore
> @@ -38,3 +38,4 @@ libbpf.pc
> libbpf.so.*
> test_hashmap
> test_btf_dump
> +xdping
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index 9b21391..2b426ae 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -26,7 +26,7 @@ TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test
> 	test_sock test_btf test_sockmap test_lirc_mode2_user get_cgroup_id_user \
> 	test_socket_cookie test_cgroup_storage test_select_reuseport test_section_names \
> 	test_netcnt test_tcpnotify_user test_sock_fields test_sysctl test_hashmap \
> -	test_btf_dump test_cgroup_attach
> +	test_btf_dump test_cgroup_attach xdping
> 
> BPF_OBJ_FILES = $(patsubst %.c,%.o, $(notdir $(wildcard progs/*.c)))
> TEST_GEN_FILES = $(BPF_OBJ_FILES)
> @@ -57,7 +57,8 @@ TEST_PROGS := test_kmod.sh \
> 	test_lwt_ip_encap.sh \
> 	test_tcp_check_syncookie.sh \
> 	test_tc_tunnel.sh \
> -	test_tc_edt.sh
> +	test_tc_edt.sh \
> +	test_xdping.sh
> 
> TEST_PROGS_EXTENDED := with_addr.sh \
> 	with_tunnels.sh \
> diff --git a/tools/testing/selftests/bpf/progs/xdping_kern.c b/tools/testing/selftests/bpf/progs/xdping_kern.c
> new file mode 100644
> index 0000000..87393e7
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/xdping_kern.c
> @@ -0,0 +1,184 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved. */
> +
> +#define KBUILD_MODNAME "foo"
> +#include <stddef.h>
> +#include <string.h>
> +#include <linux/bpf.h>
> +#include <linux/icmp.h>
> +#include <linux/in.h>
> +#include <linux/if_ether.h>
> +#include <linux/if_packet.h>
> +#include <linux/if_vlan.h>
> +#include <linux/ip.h>
> +
> +#include "bpf_helpers.h"
> +#include "bpf_endian.h"
> +
> +#include "xdping.h"
> +
> +struct bpf_map_def SEC("maps") ping_map = {
> +	.type = BPF_MAP_TYPE_HASH,
> +	.key_size = sizeof(__u32),
> +	.value_size = sizeof(struct pinginfo),
> +	.max_entries = 256,
> +};
> +
> +static __always_inline void swap_src_dst_mac(void *data)
> +{
> +	unsigned short *p = data;
> +	unsigned short dst[3];
> +
> +	dst[0] = p[0];
> +	dst[1] = p[1];
> +	dst[2] = p[2];
> +	p[0] = p[3];
> +	p[1] = p[4];
> +	p[2] = p[5];
> +	p[3] = dst[0];
> +	p[4] = dst[1];
> +	p[5] = dst[2];
> +}
> +
> +static __always_inline __u16 csum_fold_helper(__wsum sum)
> +{
> +	sum = (sum & 0xffff) + (sum >> 16);
> +	return ~((sum & 0xffff) + (sum >> 16));
> +}
> +
> +static __always_inline __u16 ipv4_csum(void *data_start, int data_size)
> +{
> +	__wsum sum;
> +
> +	sum = bpf_csum_diff(0, 0, data_start, data_size, 0);
> +	return csum_fold_helper(sum);
> +}
> +
> +#define ICMP_ECHO_LEN		64
> +
> +static __always_inline int icmp_check(struct xdp_md *ctx, int type)
> +{
> +	void *data_end = (void *)(long)ctx->data_end;
> +	void *data = (void *)(long)ctx->data;
> +	struct ethhdr *eth = data;
> +	struct icmphdr *icmph;
> +	struct iphdr *iph;
> +
> +	if (data + sizeof(*eth) + sizeof(*iph) + ICMP_ECHO_LEN > data_end)
> +		return XDP_PASS;
> +
> +	if (eth->h_proto != bpf_htons(ETH_P_IP))
> +		return XDP_PASS;
> +
> +	iph = data + sizeof(*eth);
> +
> +	if (iph->protocol != IPPROTO_ICMP)
> +		return XDP_PASS;
> +
> +	if (bpf_ntohs(iph->tot_len) - sizeof(*iph) != ICMP_ECHO_LEN)
> +		return XDP_PASS;
> +
> +	icmph = data + sizeof(*eth) + sizeof(*iph);
> +
> +	if (icmph->type != type)
> +		return XDP_PASS;
> +
> +	return XDP_TX;
> +}
> +
> +SEC("xdpclient")
> +int xdping_client(struct xdp_md *ctx)
> +{
> +	void *data_end = (void *)(long)ctx->data_end;
> +	void *data = (void *)(long)ctx->data;
> +	struct pinginfo *pinginfo = NULL;
> +	struct ethhdr *eth = data;
> +	struct icmphdr *icmph;
> +	struct iphdr *iph;
> +	__u64 recvtime;
> +	__be32 raddr;
> +	__be16 seq;
> +	int ret;
> +	__u8 i;
> +
> +	ret = icmp_check(ctx, ICMP_ECHOREPLY);
> +
> +	if (ret != XDP_TX)
> +		return ret;
> +
> +	iph = data + sizeof(*eth);
> +	icmph = data + sizeof(*eth) + sizeof(*iph);
> +	raddr = iph->saddr;
> +
> +	/* Record time reply received. */
> +	recvtime = bpf_ktime_get_ns();
> +	pinginfo = bpf_map_lookup_elem(&ping_map, &raddr);
> +	if (!pinginfo || pinginfo->seq != icmph->un.echo.sequence)
> +		return XDP_PASS;
> +
> +	if (pinginfo->start) {
> +#pragma clang loop unroll(full)
> +		for (i = 0; i < XDPING_MAX_COUNT; i++) {
> +			if (pinginfo->times[i] == 0)
> +				break;
> +		}
> +		/* verifier is fussy here... */
> +		if (i < XDPING_MAX_COUNT) {
> +			pinginfo->times[i] = recvtime -
> +					     pinginfo->start;
> +			pinginfo->start = 0;
> +			i++;
> +		}
> +		/* No more space for values? */
> +		if (i == pinginfo->count || i == XDPING_MAX_COUNT)
> +			return XDP_PASS;
> +	}
> +
> +	/* Now convert reply back into echo request. */
> +	swap_src_dst_mac(data);
> +	iph->saddr = iph->daddr;
> +	iph->daddr = raddr;
> +	icmph->type = ICMP_ECHO;
> +	seq = bpf_htons(bpf_ntohs(icmph->un.echo.sequence) + 1);
> +	icmph->un.echo.sequence = seq;
> +	icmph->checksum = 0;
> +	icmph->checksum = ipv4_csum(icmph, ICMP_ECHO_LEN);
> +
> +	pinginfo->seq = seq;
> +	pinginfo->start = bpf_ktime_get_ns();
> +
> +	return XDP_TX;
> +}
> +
> +SEC("xdpserver")
> +int xdping_server(struct xdp_md *ctx)
> +{
> +	void *data_end = (void *)(long)ctx->data_end;
> +	void *data = (void *)(long)ctx->data;
> +	struct ethhdr *eth = data;
> +	struct icmphdr *icmph;
> +	struct iphdr *iph;
> +	__be32 raddr;
> +	int ret;
> +
> +	ret = icmp_check(ctx, ICMP_ECHO);
> +
> +	if (ret != XDP_TX)
> +		return ret;
> +
> +	iph = data + sizeof(*eth);
> +	icmph = data + sizeof(*eth) + sizeof(*iph);
> +	raddr = iph->saddr;
> +
> +	/* Now convert request into echo reply. */
> +	swap_src_dst_mac(data);
> +	iph->saddr = iph->daddr;
> +	iph->daddr = raddr;
> +	icmph->type = ICMP_ECHOREPLY;
> +	icmph->checksum = 0;
> +	icmph->checksum = ipv4_csum(icmph, ICMP_ECHO_LEN);
> +
> +	return XDP_TX;
> +}
> +
> +char _license[] SEC("license") = "GPL";
> diff --git a/tools/testing/selftests/bpf/test_xdping.sh b/tools/testing/selftests/bpf/test_xdping.sh
> new file mode 100755
> index 0000000..c2f0ddb
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/test_xdping.sh
> @@ -0,0 +1,99 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +
> +# xdping tests
> +#   Here we setup and teardown configuration required to run
> +#   xdping, exercising its options.
> +#
> +#   Setup is similar to test_tunnel tests but without the tunnel.
> +#
> +# Topology:
> +# ---------
> +#     root namespace   |     tc_ns0 namespace
> +#                      |
> +#      ----------      |     ----------
> +#      |  veth1  | --------- |  veth0  |
> +#      ----------    peer    ----------
> +#
> +# Device Configuration
> +# --------------------
> +# Root namespace with BPF
> +# Device names and addresses:
> +#	veth1 IP: 10.1.1.200
> +#	xdp added to veth1, xdpings originate from here.
> +#
> +# Namespace tc_ns0 with BPF
> +# Device names and addresses:
> +#       veth0 IPv4: 10.1.1.100
> +#	For some tests xdping run in server mode here.
> +#
> +
> +readonly TARGET_IP="10.1.1.100"
> +readonly TARGET_NS="xdp_ns0"
> +
> +readonly LOCAL_IP="10.1.1.200"
> +
> +setup()
> +{
> +	ip netns add $TARGET_NS
> +	ip link add veth0 type veth peer name veth1
> +	ip link set veth0 netns $TARGET_NS
> +	ip netns exec $TARGET_NS ip addr add ${TARGET_IP}/24 dev veth0
> +	ip addr add ${LOCAL_IP}/24 dev veth1
> +	ip netns exec $TARGET_NS ip link set veth0 up
> +	ip link set veth1 up
> +}
> +
> +cleanup()
> +{
> +	set +e
> +	ip netns delete $TARGET_NS 2>/dev/null
> +	ip link del veth1 2>/dev/null
> +	if [[ $server_pid -ne 0 ]]; then
> +		kill -TERM $server_pid
> +	fi
> +}
> +
> +test()
> +{
> +	client_args="$1"
> +	server_args="$2"
> +
> +	echo "Test client args '$client_args'; server args '$server_args'"
> +
> +	server_pid=0
> +	if [[ -n "$server_args" ]]; then
> +		ip netns exec $TARGET_NS ./xdping $server_args &
> +		server_pid=$!
> +		sleep 10
> +	fi
> +	./xdping $client_args $TARGET_IP
> +
> +	if [[ $server_pid -ne 0 ]]; then
> +		kill -TERM $server_pid
> +		server_pid=0
> +	fi
> +
> +	echo "Test client args '$client_args'; server args '$server_args': PASS"
> +}
> +
> +set -e
> +
> +server_pid=0
> +
> +trap cleanup EXIT
> +
> +setup
> +
> +for server_args in "" "-I veth0 -s -S" ; do
> +	# client in skb mode
> +	client_args="-I veth1 -S"
> +	test "$client_args" "$server_args"
> +
> +	# client with count of 10 RTT measurements.
> +	client_args="-I veth1 -S -c 10"
> +	test "$client_args" "$server_args"
> +done
> +
> +echo "OK. All tests passed"
> +exit 0
> diff --git a/tools/testing/selftests/bpf/xdping.c b/tools/testing/selftests/bpf/xdping.c
> new file mode 100644
> index 0000000..d11edd1
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/xdping.c
> @@ -0,0 +1,252 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved. */
> +
> +#include <linux/bpf.h>
> +#include <linux/if_link.h>
> +#include <arpa/inet.h>
> +#include <assert.h>
> +#include <errno.h>
> +#include <signal.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <libgen.h>
> +#include <sys/resource.h>
> +#include <net/if.h>
> +#include <sys/types.h>
> +#include <sys/socket.h>
> +#include <netdb.h>
> +
> +#include "bpf/bpf.h"
> +#include "bpf/libbpf.h"
> +
> +#include "xdping.h"
> +
> +static int ifindex;
> +static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
> +
> +static void cleanup(int sig)
> +{
> +	bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
> +	if (sig)
> +		exit(1);
> +}
> +
> +static int get_stats(int fd, __u16 count, __u32 raddr)
> +{
> +	struct pinginfo pinginfo = { 0 };
> +	char inaddrbuf[INET_ADDRSTRLEN];
> +	struct in_addr inaddr;
> +	__u16 i;
> +
> +	inaddr.s_addr = raddr;
> +
> +	printf("\nXDP RTT data:\n");
> +
> +	if (bpf_map_lookup_elem(fd, &raddr, &pinginfo)) {
> +		perror("bpf_map_lookup elem: ");
> +		return 1;
> +	}
> +
> +	for (i = 0; i < count; i++) {
> +		if (pinginfo.times[i] == 0)
> +			break;
> +
> +		printf("64 bytes from %s: icmp_seq=%d ttl=64 time=%#.5f ms\n",
> +		       inet_ntop(AF_INET, &inaddr, inaddrbuf,
> +				 sizeof(inaddrbuf)),
> +		       count + i + 1,
> +		       (double)pinginfo.times[i]/1000000);
> +	}
> +
> +	if (i < count) {
> +		fprintf(stderr, "Expected %d samples, got %d.\n", count, i);
> +		return 1;
> +	}
> +
> +	bpf_map_delete_elem(fd, &raddr);
> +
> +	return 0;
> +}
> +
> +static void show_usage(const char *prog)
> +{
> +	fprintf(stderr,
> +		"usage: %s [OPTS] -I interface destination\n\n"
> +		"OPTS:\n"
> +		"    -c count		Stop after sending count requests\n"
> +		"			(default %d, max %d)\n"
> +		"    -I interface	interface name\n"
> +		"    -N			Run in driver mode\n"
> +		"    -s			Server mode\n"
> +		"    -S			Run in skb mode\n",
> +		prog, XDPING_DEFAULT_COUNT, XDPING_MAX_COUNT);
> +}
> +
> +int main(int argc, char **argv)
> +{
> +	__u32 mode_flags = XDP_FLAGS_DRV_MODE | XDP_FLAGS_SKB_MODE;
> +	struct addrinfo *a, hints = { .ai_family = AF_INET };
> +	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
> +	__u16 count = XDPING_DEFAULT_COUNT;
> +	struct pinginfo pinginfo = { 0 };
> +	const char *optstr = "c:I:NsS";
> +	struct bpf_program *main_prog;
> +	struct sockaddr_in rin;
> +	struct bpf_object *obj;
> +	int prog_fd, map_fd;
> +	struct bpf_map *map;
> +	char *ifname = NULL;
> +	char filename[256];
> +	__u32 raddr = 0;
> +	int server = 0;
> +	char cmd[256];
> +	int opt, ret;
> +
> +	while ((opt = getopt(argc, argv, optstr)) != -1) {
> +		switch (opt) {
> +		case 'c':
> +			count = atoi(optarg);
> +			if (count < 1 || count > XDPING_MAX_COUNT) {
> +				fprintf(stderr,
> +					"min count is 1, max count is %d\n",
> +					XDPING_MAX_COUNT);
> +				return 1;
> +			}
> +			break;
> +		case 'I':
> +			ifname = optarg;
> +			ifindex = if_nametoindex(ifname);
> +			if (!ifindex) {
> +				fprintf(stderr, "Could not get interface %s\n",
> +					ifname);
> +				return 1;
> +			}
> +			break;
> +		case 'N':
> +			xdp_flags |= XDP_FLAGS_DRV_MODE;
> +			break;
> +		case 's':
> +			/* use server program */
> +			server = 1;
> +			break;
> +		case 'S':
> +			xdp_flags |= XDP_FLAGS_SKB_MODE;
> +			break;
> +		default:
> +			show_usage(basename(argv[0]));
> +			return 1;
> +		}
> +	}
> +
> +	if (!ifname) {
> +		show_usage(basename(argv[0]));
> +		return 1;
> +	}
> +	if (!server && optind == argc) {
> +		show_usage(basename(argv[0]));
> +		return 1;
> +	}
> +
> +	if ((xdp_flags & mode_flags) == mode_flags) {
> +		fprintf(stderr, "-N or -S can be specified, not both.\n");
> +		show_usage(basename(argv[0]));
> +		return 1;
> +	}
> +
> +	if (!server) {
> +		/* Only supports IPv4; see hints initiailization above. */
> +		if (getaddrinfo(argv[optind], NULL, &hints, &a) || !a) {
> +			fprintf(stderr, "Could not resolve %s\n", argv[optind]);
> +			return 1;
> +		}
> +		memcpy(&rin, a->ai_addr, sizeof(rin));
> +		raddr = rin.sin_addr.s_addr;
> +		freeaddrinfo(a);
> +	}
> +
> +	if (setrlimit(RLIMIT_MEMLOCK, &r)) {
> +		perror("setrlimit(RLIMIT_MEMLOCK)");
> +		return 1;
> +	}
> +
> +	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
> +
> +	if (bpf_prog_load(filename, BPF_PROG_TYPE_XDP, &obj, &prog_fd)) {
> +		fprintf(stderr, "load of %s failed\n", filename);
> +		return 1;
> +	}
> +
> +	main_prog = bpf_object__find_program_by_title(obj,
> +						      server ? "xdpserver" :
> +							       "xdpclient");
> +	if (main_prog)
> +		prog_fd = bpf_program__fd(main_prog);
> +	if (!main_prog || prog_fd < 0) {
> +		fprintf(stderr, "could not find xdping program");
> +		return 1;
> +	}
> +
> +	map = bpf_map__next(NULL, obj);
> +	if (map)
> +		map_fd = bpf_map__fd(map);
> +	if (!map || map_fd < 0) {
> +		fprintf(stderr, "Could not find ping map");
> +		return 1;
> +	}

I am sorry I missed this one in earlier versions. But we need to 
properly close prog_fd and map_fd. 

Thanks,
Song

> +
> +	signal(SIGINT, cleanup);
> +	signal(SIGTERM, cleanup);
> +
> +	printf("Setting up XDP for %s, please wait...\n", ifname);
> +
> +	printf("XDP setup disrupts network connectivity, hit Ctrl+C to quit\n");
> +
> +	if (bpf_set_link_xdp_fd(ifindex, prog_fd, xdp_flags) < 0) {
> +		fprintf(stderr, "Link set xdp fd failed for %s\n", ifname);
> +		return 1;
> +	}
> +
> +	if (server) {
> +		printf("Running server on %s; press Ctrl+C to exit...\n",
> +		       ifname);
> +		do { } while (1);
> +	}
> +
> +	/* Start xdping-ing from last regular ping reply, e.g. for a count
> +	 * of 10 ICMP requests, we start xdping-ing using reply with seq number
> +	 * 10.  The reason the last "real" ping RTT is much higher is that
> +	 * the ping program sees the ICMP reply associated with the last
> +	 * XDP-generated packet, so ping doesn't get a reply until XDP is done.
> +	 */
> +	pinginfo.seq = htons(count);
> +	pinginfo.count = count;
> +
> +	if (bpf_map_update_elem(map_fd, &raddr, &pinginfo, BPF_ANY)) {
> +		fprintf(stderr, "could not communicate with BPF map: %s\n",
> +			strerror(errno));
> +		cleanup(1);
> +	}
> +
> +	/* We need to wait for XDP setup to complete. */
> +	sleep(10);
> +
> +	snprintf(cmd, sizeof(cmd), "ping -c %d -I %s %s",
> +		 count, ifname, argv[optind]);
> +
> +	printf("\nNormal ping RTT data\n");
> +	printf("[Ignore final RTT; it is distorted by XDP using the reply]\n");
> +
> +	ret = system(cmd);
> +
> +	if (!ret)
> +		ret = get_stats(map_fd, count, raddr);
> +
> +	cleanup(0);
> +
> +	if (ret)
> +		return 1;
> +
> +	return 0;
> +}
> diff --git a/tools/testing/selftests/bpf/xdping.h b/tools/testing/selftests/bpf/xdping.h
> new file mode 100644
> index 0000000..afc578d
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/xdping.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved. */
> +
> +#define	XDPING_MAX_COUNT	10
> +#define	XDPING_DEFAULT_COUNT	4
> +
> +struct pinginfo {
> +	__u64	start;
> +	__be16	seq;
> +	__u16	count;
> +	__u32	pad;
> +	__u64	times[XDPING_MAX_COUNT];
> +};
> -- 
> 1.8.3.1
> 

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