Merge branch 'mptcp-miscellaneous-changes-for-5-17'

Mat Martineau says:

====================
mptcp: Miscellaneous changes for 5.17

These are three unrelated patches that we've been testing in the MPTCP
tree.

Patch 1 modifies the packet scheduler that picks which TCP subflow is
used for each chunk of outgoing data. The updated scheduler improves
throughput on multiple-subflow connections.

Patch 2 updates a selftest to verify recent TCP_ULP sockopt changes
on MPTCP fallback sockets.

Patch 3 cleans up some unnecessary comparisons with an 8-bit value.
====================

Link: https://lore.kernel.org/r/20211217233702.299461-1-mathew.j.martineau@linux.intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/mptcp/pm_netlink.c

@@ -38,7 +38,8 @@ struct mptcp_pm_add_entry {
 	u8			retrans_times;
 };
 
-#define MAX_ADDR_ID		255
+/* max value of mptcp_addr_info.id */
+#define MAX_ADDR_ID		U8_MAX
 #define BITMAP_SZ DIV_ROUND_UP(MAX_ADDR_ID + 1, BITS_PER_LONG)
 
 struct pm_nl_pernet {
@@ -825,14 +826,13 @@ static int mptcp_pm_nl_append_new_local_addr(struct pm_nl_pernet *pernet,
 		entry->addr.id = find_next_zero_bit(pernet->id_bitmap,
 						    MAX_ADDR_ID + 1,
 						    pernet->next_id);
-		if ((!entry->addr.id || entry->addr.id > MAX_ADDR_ID) &&
-		    pernet->next_id != 1) {
+		if (!entry->addr.id && pernet->next_id != 1) {
 			pernet->next_id = 1;
 			goto find_next;
 		}
 	}
 
-	if (!entry->addr.id || entry->addr.id > MAX_ADDR_ID)
+	if (!entry->addr.id)
 		goto out;
 
 	__set_bit(entry->addr.id, pernet->id_bitmap);

net/mptcp/protocol.c

@@ -1372,7 +1372,7 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
 
 struct subflow_send_info {
 	struct sock *ssk;
-	u64 ratio;
+	u64 linger_time;
 };
 
 void mptcp_subflow_set_active(struct mptcp_subflow_context *subflow)
@@ -1397,20 +1397,24 @@ bool mptcp_subflow_active(struct mptcp_subflow_context *subflow)
 	return __mptcp_subflow_active(subflow);
 }
 
+#define SSK_MODE_ACTIVE	0
+#define SSK_MODE_BACKUP	1
+#define SSK_MODE_MAX	2
+
 /* implement the mptcp packet scheduler;
  * returns the subflow that will transmit the next DSS
  * additionally updates the rtx timeout
  */
 static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
 {
-	struct subflow_send_info send_info[2];
+	struct subflow_send_info send_info[SSK_MODE_MAX];
 	struct mptcp_subflow_context *subflow;
 	struct sock *sk = (struct sock *)msk;
+	u32 pace, burst, wmem;
 	int i, nr_active = 0;
 	struct sock *ssk;
+	u64 linger_time;
 	long tout = 0;
-	u64 ratio;
-	u32 pace;
 
 	sock_owned_by_me(sk);
 
@@ -1429,10 +1433,11 @@ static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
 	}
 
 	/* pick the subflow with the lower wmem/wspace ratio */
-	for (i = 0; i < 2; ++i) {
+	for (i = 0; i < SSK_MODE_MAX; ++i) {
 		send_info[i].ssk = NULL;
-		send_info[i].ratio = -1;
+		send_info[i].linger_time = -1;
 	}
+
 	mptcp_for_each_subflow(msk, subflow) {
 		trace_mptcp_subflow_get_send(subflow);
 		ssk =  mptcp_subflow_tcp_sock(subflow);
@@ -1441,34 +1446,51 @@ static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
 
 		tout = max(tout, mptcp_timeout_from_subflow(subflow));
 		nr_active += !subflow->backup;
-		if (!sk_stream_memory_free(subflow->tcp_sock) || !tcp_sk(ssk)->snd_wnd)
-			continue;
-
-		pace = READ_ONCE(ssk->sk_pacing_rate);
-		if (!pace)
-			continue;
+		pace = subflow->avg_pacing_rate;
+		if (unlikely(!pace)) {
+			/* init pacing rate from socket */
+			subflow->avg_pacing_rate = READ_ONCE(ssk->sk_pacing_rate);
+			pace = subflow->avg_pacing_rate;
+			if (!pace)
+				continue;
+		}
 
-		ratio = div_u64((u64)READ_ONCE(ssk->sk_wmem_queued) << 32,
-				pace);
-		if (ratio < send_info[subflow->backup].ratio) {
+		linger_time = div_u64((u64)READ_ONCE(ssk->sk_wmem_queued) << 32, pace);
+		if (linger_time < send_info[subflow->backup].linger_time) {
 			send_info[subflow->backup].ssk = ssk;
-			send_info[subflow->backup].ratio = ratio;
+			send_info[subflow->backup].linger_time = linger_time;
 		}
 	}
 	__mptcp_set_timeout(sk, tout);
 
 	/* pick the best backup if no other subflow is active */
 	if (!nr_active)
-		send_info[0].ssk = send_info[1].ssk;
-
-	if (send_info[0].ssk) {
-		msk->last_snd = send_info[0].ssk;
-		msk->snd_burst = min_t(int, MPTCP_SEND_BURST_SIZE,
-				       tcp_sk(msk->last_snd)->snd_wnd);
-		return msk->last_snd;
-	}
+		send_info[SSK_MODE_ACTIVE].ssk = send_info[SSK_MODE_BACKUP].ssk;
+
+	/* According to the blest algorithm, to avoid HoL blocking for the
+	 * faster flow, we need to:
+	 * - estimate the faster flow linger time
+	 * - use the above to estimate the amount of byte transferred
+	 *   by the faster flow
+	 * - check that the amount of queued data is greter than the above,
+	 *   otherwise do not use the picked, slower, subflow
+	 * We select the subflow with the shorter estimated time to flush
+	 * the queued mem, which basically ensure the above. We just need
+	 * to check that subflow has a non empty cwin.
+	 */
+	ssk = send_info[SSK_MODE_ACTIVE].ssk;
+	if (!ssk || !sk_stream_memory_free(ssk) || !tcp_sk(ssk)->snd_wnd)
+		return NULL;
 
-	return NULL;
+	burst = min_t(int, MPTCP_SEND_BURST_SIZE, tcp_sk(ssk)->snd_wnd);
+	wmem = READ_ONCE(ssk->sk_wmem_queued);
+	subflow = mptcp_subflow_ctx(ssk);
+	subflow->avg_pacing_rate = div_u64((u64)subflow->avg_pacing_rate * wmem +
+					   READ_ONCE(ssk->sk_pacing_rate) * burst,
+					   burst + wmem);
+	msk->last_snd = ssk;
+	msk->snd_burst = burst;
+	return ssk;
 }
 
 static void mptcp_push_release(struct sock *ssk, struct mptcp_sendmsg_info *info)

net/mptcp/protocol.h

@@ -395,6 +395,7 @@ DECLARE_PER_CPU(struct mptcp_delegated_action, mptcp_delegated_actions);
 /* MPTCP subflow context */
 struct mptcp_subflow_context {
 	struct	list_head node;/* conn_list of subflows */
+	unsigned long avg_pacing_rate; /* protected by msk socket lock */
 	u64	local_key;
 	u64	remote_key;
 	u64	idsn;

tools/testing/selftests/net/mptcp/mptcp_connect.c

@@ -59,7 +59,6 @@ static enum cfg_peek cfg_peek = CFG_NONE_PEEK;
 static const char *cfg_host;
 static const char *cfg_port	= "12000";
 static int cfg_sock_proto	= IPPROTO_MPTCP;
-static bool tcpulp_audit;
 static int pf = AF_INET;
 static int cfg_sndbuf;
 static int cfg_rcvbuf;
@@ -103,7 +102,6 @@ static void die_usage(void)
 	fprintf(stderr, "\t-s [MPTCP|TCP] -- use mptcp(default) or tcp sockets\n");
 	fprintf(stderr, "\t-m [poll|mmap|sendfile] -- use poll(default)/mmap+write/sendfile\n");
 	fprintf(stderr, "\t-M mark -- set socket packet mark\n");
-	fprintf(stderr, "\t-u -- check mptcp ulp\n");
 	fprintf(stderr, "\t-w num -- wait num sec before closing the socket\n");
 	fprintf(stderr, "\t-c cmsg -- test cmsg type <cmsg>\n");
 	fprintf(stderr, "\t-o option -- test sockopt <option>\n");
@@ -215,6 +213,42 @@ static void set_transparent(int fd, int pf)
 	}
 }
 
+static int do_ulp_so(int sock, const char *name)
+{
+	return setsockopt(sock, IPPROTO_TCP, TCP_ULP, name, strlen(name));
+}
+
+#define X(m)	xerror("%s:%u: %s: failed for proto %d at line %u", __FILE__, __LINE__, (m), proto, line)
+static void sock_test_tcpulp(int sock, int proto, unsigned int line)
+{
+	socklen_t buflen = 8;
+	char buf[8] = "";
+	int ret = getsockopt(sock, IPPROTO_TCP, TCP_ULP, buf, &buflen);
+
+	if (ret != 0)
+		X("getsockopt");
+
+	if (buflen > 0) {
+		if (strcmp(buf, "mptcp") != 0)
+			xerror("unexpected ULP '%s' for proto %d at line %u", buf, proto, line);
+		ret = do_ulp_so(sock, "tls");
+		if (ret == 0)
+			X("setsockopt");
+	} else if (proto == IPPROTO_MPTCP) {
+		ret = do_ulp_so(sock, "tls");
+		if (ret != -1)
+			X("setsockopt");
+	}
+
+	ret = do_ulp_so(sock, "mptcp");
+	if (ret != -1)
+		X("setsockopt");
+
+#undef X
+}
+
+#define SOCK_TEST_TCPULP(s, p) sock_test_tcpulp((s), (p), __LINE__)
+
 static int sock_listen_mptcp(const char * const listenaddr,
 			     const char * const port)
 {
@@ -238,6 +272,8 @@ static int sock_listen_mptcp(const char * const listenaddr,
 		if (sock < 0)
 			continue;
 
+		SOCK_TEST_TCPULP(sock, cfg_sock_proto);
+
 		if (-1 == setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &one,
 				     sizeof(one)))
 			perror("setsockopt");
@@ -260,50 +296,17 @@ static int sock_listen_mptcp(const char * const listenaddr,
 		return sock;
 	}
 
+	SOCK_TEST_TCPULP(sock, cfg_sock_proto);
+
 	if (listen(sock, 20)) {
 		perror("listen");
 		close(sock);
 		return -1;
 	}
 
-	return sock;
-}
+	SOCK_TEST_TCPULP(sock, cfg_sock_proto);
 
-static bool sock_test_tcpulp(const char * const remoteaddr,
-			     const char * const port)
-{
-	struct addrinfo hints = {
-		.ai_protocol = IPPROTO_TCP,
-		.ai_socktype = SOCK_STREAM,
-	};
-	struct addrinfo *a, *addr;
-	int sock = -1, ret = 0;
-	bool test_pass = false;
-
-	hints.ai_family = AF_INET;
-
-	xgetaddrinfo(remoteaddr, port, &hints, &addr);
-	for (a = addr; a; a = a->ai_next) {
-		sock = socket(a->ai_family, a->ai_socktype, IPPROTO_TCP);
-		if (sock < 0) {
-			perror("socket");
-			continue;
-		}
-		ret = setsockopt(sock, IPPROTO_TCP, TCP_ULP, "mptcp",
-				 sizeof("mptcp"));
-		if (ret == -1 && errno == EOPNOTSUPP)
-			test_pass = true;
-		close(sock);
-
-		if (test_pass)
-			break;
-		if (!ret)
-			fprintf(stderr,
-				"setsockopt(TCP_ULP) returned 0\n");
-		else
-			perror("setsockopt(TCP_ULP)");
-	}
-	return test_pass;
+	return sock;
 }
 
 static int sock_connect_mptcp(const char * const remoteaddr,
@@ -326,6 +329,8 @@ static int sock_connect_mptcp(const char * const remoteaddr,
 			continue;
 		}
 
+		SOCK_TEST_TCPULP(sock, proto);
+
 		if (cfg_mark)
 			set_mark(sock, cfg_mark);
 
@@ -338,6 +343,8 @@ static int sock_connect_mptcp(const char * const remoteaddr,
 	}
 
 	freeaddrinfo(addr);
+	if (sock != -1)
+		SOCK_TEST_TCPULP(sock, proto);
 	return sock;
 }
 
@@ -954,6 +961,8 @@ int main_loop_s(int listensock)
 		check_sockaddr(pf, &ss, salen);
 		check_getpeername(remotesock, &ss, salen);
 
+		SOCK_TEST_TCPULP(remotesock, 0);
+
 		return copyfd_io(0, remotesock, 1);
 	}
 
@@ -1059,6 +1068,8 @@ int main_loop(void)
 
 	check_getpeername_connect(fd);
 
+	SOCK_TEST_TCPULP(fd, cfg_sock_proto);
+
 	if (cfg_rcvbuf)
 		set_rcvbuf(fd, cfg_rcvbuf);
 	if (cfg_sndbuf)
@@ -1151,7 +1162,7 @@ static void parse_opts(int argc, char **argv)
 {
 	int c;
 
-	while ((c = getopt(argc, argv, "6jr:lp:s:hut:T:m:S:R:w:M:P:c:o:")) != -1) {
+	while ((c = getopt(argc, argv, "6jr:lp:s:ht:T:m:S:R:w:M:P:c:o:")) != -1) {
 		switch (c) {
 		case 'j':
 			cfg_join = true;
@@ -1177,9 +1188,6 @@ static void parse_opts(int argc, char **argv)
 		case 'h':
 			die_usage();
 			break;
-		case 'u':
-			tcpulp_audit = true;
-			break;
 		case '6':
 			pf = AF_INET6;
 			break;
@@ -1233,9 +1241,6 @@ int main(int argc, char *argv[])
 	signal(SIGUSR1, handle_signal);
 	parse_opts(argc, argv);
 
-	if (tcpulp_audit)
-		return sock_test_tcpulp(cfg_host, cfg_port) ? 0 : 1;
-
 	if (listen_mode) {
 		int fd = sock_listen_mptcp(cfg_host, cfg_port);
 

tools/testing/selftests/net/mptcp/mptcp_connect.sh

@@ -296,24 +296,6 @@ check_mptcp_disabled()
 	return 0
 }
 
-check_mptcp_ulp_setsockopt()
-{
-	local t retval
-	t="ns_ulp-$sech-$(mktemp -u XXXXXX)"
-
-	ip netns add ${t} || exit $ksft_skip
-	if ! ip netns exec ${t} ./mptcp_connect -u -p 10000 -s TCP 127.0.0.1 2>&1; then
-		printf "setsockopt(..., TCP_ULP, \"mptcp\", ...) allowed\t[ FAIL ]\n"
-		retval=1
-		ret=$retval
-	else
-		printf "setsockopt(..., TCP_ULP, \"mptcp\", ...) blocked\t[ OK ]\n"
-		retval=0
-	fi
-	ip netns del ${t}
-	return $retval
-}
-
 # $1: IP address
 is_v6()
 {
@@ -780,8 +762,6 @@ make_file "$sin" "server"
 
 check_mptcp_disabled
 
-check_mptcp_ulp_setsockopt
-
 stop_if_error "The kernel configuration is not valid for MPTCP"
 
 echo "INFO: validating network environment with pings"