diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index df9102ec7b7a..0a1821f8dfb1 100644
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -9,7 +9,7 @@ TEST_PROGS += fib_tests.sh fib-onlink-tests.sh in_netns.sh pmtu.sh udpgso.sh
 TEST_PROGS += udpgso_bench.sh
 TEST_GEN_FILES =  socket
 TEST_GEN_FILES += psock_fanout psock_tpacket msg_zerocopy
-TEST_GEN_FILES += tcp_mmap
+TEST_GEN_FILES += tcp_mmap tcp_inq
 TEST_GEN_PROGS = reuseport_bpf reuseport_bpf_cpu reuseport_bpf_numa
 TEST_GEN_PROGS += reuseport_dualstack reuseaddr_conflict
 TEST_GEN_PROGS += udpgso udpgso_bench_tx udpgso_bench_rx
@@ -18,3 +18,4 @@ include ../lib.mk
 
 $(OUTPUT)/reuseport_bpf_numa: LDFLAGS += -lnuma
 $(OUTPUT)/tcp_mmap: LDFLAGS += -lpthread
+$(OUTPUT)/tcp_inq: LDFLAGS += -lpthread
diff --git a/tools/testing/selftests/net/tcp_inq.c b/tools/testing/selftests/net/tcp_inq.c
new file mode 100644
index 000000000000..d044b29ddabc
--- /dev/null
+++ b/tools/testing/selftests/net/tcp_inq.c
@@ -0,0 +1,189 @@
+/*
+ * Copyright 2018 Google Inc.
+ * Author: Soheil Hassas Yeganeh (soheil@google.com)
+ *
+ * Simple example on how to use TCP_INQ and TCP_CM_INQ.
+ *
+ * License (GPLv2):
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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 _GNU_SOURCE
+
+#include <error.h>
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+#ifndef TCP_INQ
+#define TCP_INQ 36
+#endif
+
+#ifndef TCP_CM_INQ
+#define TCP_CM_INQ TCP_INQ
+#endif
+
+#define BUF_SIZE 8192
+#define CMSG_SIZE 32
+
+static int family = AF_INET6;
+static socklen_t addr_len = sizeof(struct sockaddr_in6);
+static int port = 4974;
+
+static void setup_loopback_addr(int family, struct sockaddr_storage *sockaddr)
+{
+	struct sockaddr_in6 *addr6 = (void *) sockaddr;
+	struct sockaddr_in *addr4 = (void *) sockaddr;
+
+	switch (family) {
+	case PF_INET:
+		memset(addr4, 0, sizeof(*addr4));
+		addr4->sin_family = AF_INET;
+		addr4->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+		addr4->sin_port = htons(port);
+		break;
+	case PF_INET6:
+		memset(addr6, 0, sizeof(*addr6));
+		addr6->sin6_family = AF_INET6;
+		addr6->sin6_addr = in6addr_loopback;
+		addr6->sin6_port = htons(port);
+		break;
+	default:
+		error(1, 0, "illegal family");
+	}
+}
+
+void *start_server(void *arg)
+{
+	int server_fd = (int)(unsigned long)arg;
+	struct sockaddr_in addr;
+	socklen_t addrlen = sizeof(addr);
+	char *buf;
+	int fd;
+	int r;
+
+	buf = malloc(BUF_SIZE);
+
+	for (;;) {
+		fd = accept(server_fd, (struct sockaddr *)&addr, &addrlen);
+		if (fd == -1) {
+			perror("accept");
+			break;
+		}
+		do {
+			r = send(fd, buf, BUF_SIZE, 0);
+		} while (r < 0 && errno == EINTR);
+		if (r < 0)
+			perror("send");
+		if (r != BUF_SIZE)
+			fprintf(stderr, "can only send %d bytes\n", r);
+		/* TCP_INQ can overestimate in-queue by one byte if we send
+		 * the FIN packet. Sleep for 1 second, so that the client
+		 * likely invoked recvmsg().
+		 */
+		sleep(1);
+		close(fd);
+	}
+
+	free(buf);
+	close(server_fd);
+	pthread_exit(0);
+}
+
+int main(int argc, char *argv[])
+{
+	struct sockaddr_storage listen_addr, addr;
+	int c, one = 1, inq = -1;
+	pthread_t server_thread;
+	char cmsgbuf[CMSG_SIZE];
+	struct iovec iov[1];
+	struct cmsghdr *cm;
+	struct msghdr msg;
+	int server_fd, fd;
+	char *buf;
+
+	while ((c = getopt(argc, argv, "46p:")) != -1) {
+		switch (c) {
+		case '4':
+			family = PF_INET;
+			addr_len = sizeof(struct sockaddr_in);
+			break;
+		case '6':
+			family = PF_INET6;
+			addr_len = sizeof(struct sockaddr_in6);
+			break;
+		case 'p':
+			port = atoi(optarg);
+			break;
+		}
+	}
+
+	server_fd = socket(family, SOCK_STREAM, 0);
+	if (server_fd < 0)
+		error(1, errno, "server socket");
+	setup_loopback_addr(family, &listen_addr);
+	if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR,
+		       &one, sizeof(one)) != 0)
+		error(1, errno, "setsockopt(SO_REUSEADDR)");
+	if (bind(server_fd, (const struct sockaddr *)&listen_addr,
+		 addr_len) == -1)
+		error(1, errno, "bind");
+	if (listen(server_fd, 128) == -1)
+		error(1, errno, "listen");
+	if (pthread_create(&server_thread, NULL, start_server,
+			   (void *)(unsigned long)server_fd) != 0)
+		error(1, errno, "pthread_create");
+
+	fd = socket(family, SOCK_STREAM, 0);
+	if (fd < 0)
+		error(1, errno, "client socket");
+	setup_loopback_addr(family, &addr);
+	if (connect(fd, (const struct sockaddr *)&addr, addr_len) == -1)
+		error(1, errno, "connect");
+	if (setsockopt(fd, SOL_TCP, TCP_INQ, &one, sizeof(one)) != 0)
+		error(1, errno, "setsockopt(TCP_INQ)");
+
+	msg.msg_name = NULL;
+	msg.msg_namelen = 0;
+	msg.msg_iov = iov;
+	msg.msg_iovlen = 1;
+	msg.msg_control = cmsgbuf;
+	msg.msg_controllen = sizeof(cmsgbuf);
+	msg.msg_flags = 0;
+
+	buf = malloc(BUF_SIZE);
+	iov[0].iov_base = buf;
+	iov[0].iov_len = BUF_SIZE / 2;
+
+	if (recvmsg(fd, &msg, 0) != iov[0].iov_len)
+		error(1, errno, "recvmsg");
+	if (msg.msg_flags & MSG_CTRUNC)
+		error(1, 0, "control message is truncated");
+
+	for (cm = CMSG_FIRSTHDR(&msg); cm; cm = CMSG_NXTHDR(&msg, cm))
+		if (cm->cmsg_level == SOL_TCP && cm->cmsg_type == TCP_CM_INQ)
+			inq = *((int *) CMSG_DATA(cm));
+
+	if (inq != BUF_SIZE - iov[0].iov_len) {
+		fprintf(stderr, "unexpected inq: %d\n", inq);
+		exit(1);
+	}
+
+	printf("PASSED\n");
+	free(buf);
+	close(fd);
+	return 0;
+}