selftests: udp gso with corking

Corked sockets take a different path to construct a udp datagram than
the lockless fast path. Test this alternate path.

Signed-off-by: Willem de Bruijn <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

tools/testing/selftests/net/udpgso.c

···
 static bool		cfg_do_ipv6;
 static bool		cfg_do_connected;
 static bool		cfg_do_connectionless;
+static bool		cfg_do_msgmore;
 static bool		cfg_do_setsockopt;
 static int		cfg_specific_test_id = -1;
 
···
 	fprintf(stderr, "route mtu (test): %u\n", mtu);
 }
 
+static bool __send_one(int fd, struct msghdr *msg, int flags)
+{
+	int ret;
+
+	ret = sendmsg(fd, msg, flags);
+	if (ret == -1 && (errno == EMSGSIZE || errno == ENOMEM))
+		return false;
+	if (ret == -1)
+		error(1, errno, "sendmsg");
+	if (ret != msg->msg_iov->iov_len)
+		error(1, 0, "sendto: %d != %lu", ret, msg->msg_iov->iov_len);
+	if (msg->msg_flags)
+		error(1, 0, "sendmsg: return flags 0x%x\n", msg->msg_flags);
+
+	return true;
+}
+
 static bool send_one(int fd, int len, int gso_len,
 		     struct sockaddr *addr, socklen_t alen)
 {
···
 	struct msghdr msg = {0};
 	struct iovec iov = {0};
 	struct cmsghdr *cm;
-	int ret;
 
 	iov.iov_base = buf;
 	iov.iov_len = len;
···
 		*((uint16_t *) CMSG_DATA(cm)) = gso_len;
 	}
 
-	ret = sendmsg(fd, &msg, 0);
-	if (ret == -1 && (errno == EMSGSIZE || errno == ENOMEM))
-		return false;
-	if (ret == -1)
-		error(1, errno, "sendmsg");
-	if (ret != len)
-		error(1, 0, "sendto: %d != %u", ret, len);
+	/* If MSG_MORE, send 1 byte followed by remainder */
+	if (cfg_do_msgmore && len > 1) {
+		iov.iov_len = 1;
+		if (!__send_one(fd, &msg, MSG_MORE))
+			error(1, 0, "send 1B failed");
 
-	return true;
+		iov.iov_base++;
+		iov.iov_len = len - 1;
+	}
+
+	return __send_one(fd, &msg, 0);
 }
 
 static int recv_one(int fd, int flags)
···
 {
 	int c;
 
-	while ((c = getopt(argc, argv, "46cCst:")) != -1) {
+	while ((c = getopt(argc, argv, "46cCmst:")) != -1) {
 		switch (c) {
 		case '4':
 			cfg_do_ipv4 = true;
···
 			break;
 		case 'C':
 			cfg_do_connectionless = true;
+			break;
+		case 'm':
+			cfg_do_msgmore = true;
 			break;
 		case 's':
 			cfg_do_setsockopt = true;

tools/testing/selftests/net/udpgso.sh

···
 # blocked on 2nd loopback address
 # echo "ipv6 connected"
 # ./in_netns.sh ./udpgso -6 -c
+
+echo "ipv4 msg_more"
+./in_netns.sh ./udpgso -4 -C -m
+
+echo "ipv6 msg_more"
+./in_netns.sh ./udpgso -6 -C -m