Revert "selftests/bpf: Support nonblock for send_recv_data"

This reverts commit 8fdb31d.

tools/testing/selftests/bpf/network_helpers.c

@@ -580,7 +580,6 @@ struct send_recv_arg {
 static void *send_recv_server(void *arg)
 {
 	struct send_recv_arg *a = (struct send_recv_arg *)arg;
-	int flags = fcntl(a->fd, F_GETFL);
 	ssize_t nr_sent = 0, bytes = 0;
 	char batch[1500];
 	int err = 0, fd;
@@ -604,8 +603,6 @@ static void *send_recv_server(void *arg)
 		if (nr_sent == -1 && errno == EINTR)
 			continue;
 		if (nr_sent == -1) {
-			if (flags & O_NONBLOCK && errno == EWOULDBLOCK)
-				continue;
 			err = -errno;
 			break;
 		}
@@ -630,7 +627,6 @@ static void *send_recv_server(void *arg)
 
 int send_recv_data(int lfd, int fd, uint32_t total_bytes)
 {
-	int flags = fcntl(lfd, F_GETFL);
 	ssize_t nr_recv = 0, bytes = 0;
 	struct send_recv_arg arg = {
 		.fd	= lfd,
@@ -655,8 +651,6 @@ int send_recv_data(int lfd, int fd, uint32_t total_bytes)
 		if (nr_recv == -1 && errno == EINTR)
 			continue;
 		if (nr_recv == -1) {
-			if (flags & O_NONBLOCK && errno == EWOULDBLOCK)
-				continue;
 			err = -errno;
 			break;
 		}

tools/testing/selftests/bpf/prog_tests/mptcp.c

@@ -363,16 +363,6 @@ static void test_mptcpify(void)
 	close(cgroup_fd);
 }
 
-static inline int set_nonblock(int fd)
-{
-	int flags = fcntl(fd, F_GETFL);
-
-	if (flags == -1 || flags & O_NONBLOCK)
-		return -1;
-
-	return fcntl(fd, F_SETFL, flags | O_NONBLOCK);
-}
-
 static int endpoint_init(char *flags)
 {
 	SYS(fail, "ip -net %s link add veth1 type veth peer name veth2", NS_TEST);
@@ -416,9 +406,6 @@ static void run_subflow(char *new)
 	if (!ASSERT_GE(client_fd, 0, "connect to fd"))
 		goto fail;
 
-	if (set_nonblock(server_fd))
-		goto fail;
-
 	err = getsockopt(server_fd, SOL_TCP, TCP_CONGESTION, cc, &len);
 	if (!ASSERT_OK(err, "getsockopt(srv_fd, TCP_CONGESTION)"))
 		goto fail;
@@ -513,9 +500,6 @@ static void send_data_and_verify(char *sched, bool addr1, bool addr2)
 	if (CHECK(client_fd < 0, sched, "connect_to_fd: %d\n", errno))
 		goto fail;
 
-	if (set_nonblock(server_fd))
-		goto fail;
-
 	if (clock_gettime(CLOCK_MONOTONIC, &start) < 0)
 		goto fail;