Re: [PATCH bpf-next v5 5/5] bpf/selftests: add selftest for bpf_smc_ops

[Martin KaFai Lau <martin.lau@linux.dev>]

On 1/6/25 8:17 PM, D. Wythe wrote:
> +static int send_cmd(int fd, __u16 nlmsg_type, __u32 nlmsg_pid, __u16 nlmsg_flags,
> +			__u8 genl_cmd, __u16 nla_type,
> +			void *nla_data, int nla_len)
> +{
> +	struct nlattr *na;
> +	struct sockaddr_nl nladdr;
> +	int r, buflen;
> +	char *buf;
> +
> +	struct msgtemplate msg = {0};
> +
> +	msg.n.nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);
> +	msg.n.nlmsg_type = nlmsg_type;
> +	msg.n.nlmsg_flags = nlmsg_flags;
> +	msg.n.nlmsg_seq = 0;
> +	msg.n.nlmsg_pid = nlmsg_pid;
> +	msg.g.cmd = genl_cmd;
> +	msg.g.version = 1;
> +	na = (struct nlattr *) GENLMSG_DATA(&msg);
> +	na->nla_type = nla_type;
> +	na->nla_len = nla_len + 1 + NLA_HDRLEN;
> +	memcpy(NLA_DATA(na), nla_data, nla_len);
> +	msg.n.nlmsg_len += NLMSG_ALIGN(na->nla_len);
> +
> +	buf = (char *) &msg;
> +	buflen = msg.n.nlmsg_len;
> +	memset(&nladdr, 0, sizeof(nladdr));
> +	nladdr.nl_family = AF_NETLINK;
> +
> +	while ((r = sendto(fd, buf, buflen, 0, (struct sockaddr *) &nladdr,
> +			   sizeof(nladdr))) < buflen) {
> +		if (r > 0) {
> +			buf += r;
> +			buflen -= r;
> +		} else if (errno != EAGAIN)
> +			return -1;
> +		}

The "}" indentation is off.

I was wondering if it missed a "}" for the while loop. Turns out the "else if" 
does not have braces while the "if" has. I would add braces to the "else if" 
also to avoid confusion like this.

> +	return 0;
> +}
> +
> +static bool get_smc_nl_family_id(void)
> +{
> +	struct sockaddr_nl nl_src;
> +	struct msgtemplate msg;
> +	struct nlattr *nl;
> +	int fd, ret;
> +	pid_t pid;
> +
> +	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
> +	if (!ASSERT_GT(fd, 0, "nl_family socket"))
> +		return false;
> +
> +	pid = getpid();
> +
> +	memset(&nl_src, 0, sizeof(nl_src));
> +	nl_src.nl_family = AF_NETLINK;
> +	nl_src.nl_pid = pid;
> +
> +	ret = bind(fd, (struct sockaddr *) &nl_src, sizeof(nl_src));
> +	if (!ASSERT_GE(ret, 0, "nl_family bind"))
> +		goto fail;
> +
> +	ret = send_cmd(fd, GENL_ID_CTRL, pid,
> +		       NLM_F_REQUEST, CTRL_CMD_GETFAMILY,
> +		       CTRL_ATTR_FAMILY_NAME, (void *)SMC_GENL_FAMILY_NAME,
> +		       strlen(SMC_GENL_FAMILY_NAME));
> +	if (!ASSERT_EQ(ret, 0, "nl_family query"))
> +		goto fail;
> +
> +	ret = recv(fd, &msg, sizeof(msg), 0);
> +	if (!ASSERT_FALSE(msg.n.nlmsg_type == NLMSG_ERROR || (ret < 0) ||
> +			  !NLMSG_OK((&msg.n), ret), "nl_family response"))
> +		goto fail;
> +
> +	nl = (struct nlattr *) GENLMSG_DATA(&msg);
> +	nl = (struct nlattr *) ((char *) nl + NLA_ALIGN(nl->nla_len));
> +	if (!ASSERT_EQ(nl->nla_type, CTRL_ATTR_FAMILY_ID, "nl_family nla type"))
> +		goto fail;
> +
> +	smc_nl_family_id = *(uint16_t *) NLA_DATA(nl);
> +	close(fd);
> +	return true;
> +fail:
> +	close(fd);
> +	return false;
> +}
> +
> +static bool smc_ueid(int op)
> +{
> +	struct sockaddr_nl nl_src;
> +	struct msgtemplate msg;
> +	struct nlmsgerr *err;
> +	char test_ueid[32];
> +	int fd, ret;
> +	pid_t pid;
> +
> +	/* UEID required */
> +	memset(test_ueid, '\x20', sizeof(test_ueid));
> +	memcpy(test_ueid, SMC_BPFTEST_UEID, strlen(SMC_BPFTEST_UEID));
> +	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
> +	if (!ASSERT_GT(fd, 0, "ueid socket"))
> +		return false;
> +
> +	pid = getpid();
> +	memset(&nl_src, 0, sizeof(nl_src));
> +	nl_src.nl_family = AF_NETLINK;
> +	nl_src.nl_pid = pid;
> +
> +	ret = bind(fd, (struct sockaddr *) &nl_src, sizeof(nl_src));
> +	if (!ASSERT_GE(ret, 0, "ueid bind"))
> +		goto fail;
> +
> +	ret = send_cmd(fd, smc_nl_family_id, pid,
> +		       NLM_F_REQUEST | NLM_F_ACK, op, SMC_NLA_EID_TABLE_ENTRY,
> +	(void *)test_ueid, sizeof(test_ueid));

Same. Indentation is off.

> +	if (!ASSERT_EQ(ret, 0, "ueid cmd"))
> +		goto fail;
> +
> +	ret = recv(fd, &msg, sizeof(msg), 0);
> +	if (!ASSERT_FALSE((ret < 0) || !NLMSG_OK((&msg.n), ret), "ueid response"))
> +		goto fail;
> +
> +	if (msg.n.nlmsg_type == NLMSG_ERROR) {
> +		err = NLMSG_DATA(&msg);
> +		switch (op) {
> +		case SMC_NETLINK_REMOVE_UEID:
> +			if (!ASSERT_FALSE((err->error && err->error != -ENOENT), "ueid remove"))
> +				goto fail;
> +			break;
> +		case SMC_NETLINK_ADD_UEID:
> +			if (!ASSERT_EQ(err->error, 0, "ueid add"))
> +				goto fail;
> +			break;
> +		default:
> +			break;
> +		}
> +	}
> +	close(fd);
> +	return true;
> +fail:
> +	close(fd);
> +	return false;
> +}
> +
> +static bool setup_netns(void)
> +{
> +	if (!ASSERT_OK(make_netns(TEST_NS), "create net namespace"))
> +		return false;
> +
> +	nstoken = open_netns(TEST_NS);

Instead of make_netns and then immediately open_netns, try netns_new(TEST_NS, 
true) from the test_progs.c.

> +	if (!ASSERT_OK_PTR(nstoken, "open net namespace"))
> +		goto fail_open_netns;
> +
> +	if (!ASSERT_OK(system("ip addr add 127.0.1.0/8 dev lo"), "add server node"))
> +		goto fail_ip;
> +
> +	if (!ASSERT_OK(system("ip addr add 127.0.2.0/8 dev lo"), "server via risk path"))
> +		goto fail_ip;
> +
> +	return true;
> +fail_open_netns:
> +	remove_netns(TEST_NS);
> +fail_ip:
> +	close_netns(nstoken);
> +	return false;
> +}
> +
> +static void cleanup_netns(void)
> +{
> +	close_netns(nstoken);
> +	remove_netns(TEST_NS);
> +}
> +
> +static bool setup_ueid(void)
> +{
> +	/* get smc nl id */
> +	if (!get_smc_nl_family_id())
> +		return false;
> +	/* clear old ueid for bpftest */
> +	smc_ueid(SMC_NETLINK_REMOVE_UEID);
> +	/* smc-loopback required ueid */
> +	return smc_ueid(SMC_NETLINK_ADD_UEID);
> +}
> +
> +static void cleanup_ueid(void)
> +{
> +	smc_ueid(SMC_NETLINK_REMOVE_UEID);
> +}
> +
> +static bool setup_smc(void)
> +{
> +	if (!setup_ueid())
> +		return false;
> +
> +	if (!setup_netns())
> +		goto fail_netns;
> +
> +	return true;
> +fail_netns:
> +	cleanup_ueid();
> +	return false;
> +}
> +
> +static int set_client_addr_cb(int fd, void *opts)
> +{
> +	const char *src = (const char *)opts;
> +	struct sockaddr_in localaddr;
> +
> +	localaddr.sin_family = AF_INET;
> +	localaddr.sin_port = htons(0);
> +	localaddr.sin_addr.s_addr = inet_addr(src);
> +	return !ASSERT_EQ(bind(fd, &localaddr, sizeof(localaddr)), 0, "client bind");
> +}
> +
> +static void run_link(const char *src, const char *dst, int port)
> +{
> +	struct network_helper_opts opts = {0};
> +	int server, client;
> +
> +	server = start_server_str(AF_INET, SOCK_STREAM, dst, port, NULL);
> +	if (!ASSERT_OK_FD(server, "start service_1"))
> +		return;
> +
> +	opts.proto = IPPROTO_TCP;
> +	opts.post_socket_cb = set_client_addr_cb;
> +	opts.cb_opts = (void *)src;
> +
> +	client = connect_to_fd_opts(server, &opts);
> +	if (!ASSERT_OK_FD(client, "start connect"))
> +		goto fail_client;
> +
> +	close(client);
> +fail_client:
> +	close(server);
> +}
> +
> +static void block_link(int map_fd, const char *src, const char *dst)
> +{
> +	struct smc_strat_ip_value val = { .mode = /* block */ 0 };
> +	struct smc_strat_ip_key key = {
> +		.sip = inet_addr(src),
> +		.dip = inet_addr(dst),
> +	};
> +
> +	bpf_map_update_elem(map_fd, &key, &val, BPF_ANY);
> +}
> +
> +/*
> + * This test describes a real-life service topology as follows:
> + *
> + *                             +-------------> service_1
> + *            link1            |                     |
> + *   +--------------------> server                   |  link 2
> + *   |                         |                     V
> + *   |                         +-------------> service_2
> + *   |        link 3
> + *  client -------------------> server_via_unsafe_path -> service_3
> + *
> + * Among them,
> + * 1. link-1 is very suitable for using SMC.
> + * 2. link-2 is not suitable for using SMC, because the mode of this link is kind of
> + *     short-link services.
> + * 3. link-3 is also not suitable for using SMC, because the RDMA link is unavailable and
> + *     needs to go through a long timeout before it can fallback to TCP.
> + *
> + * To achieve this goal, we use a customized SMC ip strategy via smc_ops.
> + */
> +static void test_topo(void)
> +{
> +	struct bpf_smc *skel;
> +	int rc, map_fd;
> +
> +	skel = bpf_smc__open_and_load();
> +	if (!ASSERT_OK_PTR(skel, "bpf_smc__open_and_load"))
> +		return;
> +
> +	rc = bpf_smc__attach(skel);
> +	if (!ASSERT_EQ(rc, 0, "bpf_smc__attach"))
> +		goto fail;
> +
> +	map_fd = bpf_map__fd(skel->maps.smc_strats_ip);
> +	if (!ASSERT_GT(map_fd, 0, "bpf_map__fd"))
> +		goto fail;
> +
> +	/* Mock the process of transparent replacement, since we will modify protocol
> +	 * to ipproto_smc accropding to it via fmod_ret/update_socket_protocol.
> +	 */
> +	system("sysctl -w net.smc.ops=linkcheck");
> +
> +	/* Configure ip strat */
> +	block_link(map_fd, CLIENT_IP, SERVER_IP_VIA_RISK_PATH);
> +	block_link(map_fd, SERVER_IP, SERVER_IP);
> +	close(map_fd);

No need to close(map-fd) here. bpf_smc__destroy(skel) will do it.

It seems the new selftest fails also. not always though which is concerning.

pw-bot: cr

> +
> +	/* should go with smc */
> +	run_link(CLIENT_IP, SERVER_IP, SERVICE_1);
> +	/* should go with smc fallback */
> +	run_link(SERVER_IP, SERVER_IP, SERVICE_2);
> +
> +	ASSERT_EQ(skel->bss->smc_cnt, 2, "smc count");
> +	ASSERT_EQ(skel->bss->fallback_cnt, 1, "fallback count");
> +
> +	/* should go with smc */
> +	run_link(CLIENT_IP, SERVER_IP, SERVICE_2);
> +
> +	ASSERT_EQ(skel->bss->smc_cnt, 3, "smc count");
> +	ASSERT_EQ(skel->bss->fallback_cnt, 1, "fallback count");
> +
> +	/* should go with smc fallback */
> +	run_link(CLIENT_IP, SERVER_IP_VIA_RISK_PATH, SERVICE_3);
> +
> +	ASSERT_EQ(skel->bss->smc_cnt, 4, "smc count");
> +	ASSERT_EQ(skel->bss->fallback_cnt, 2, "fallback count");
> +
> +fail:
> +	bpf_smc__destroy(skel);
> +}