From: Geliang Tang <tanggeliang@kylinos.cn>

Add a helper to conditionally set TCP_INQ sockopt on accepted sockets
when running in inq mode. This ensures proper testing of TCP_CM_INQ
functionality by enabling the required socket option on both ends of
the connection. This setup is necessary for validating TCP_CM_INQ
behavior during TCP_INQ-specific tests.

These codes are from mptcp_inq.c.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
---
 tools/testing/selftests/net/mptcp/mptcp_sockopt.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c b/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
index 776a017577ce..aadef8b0aea4 100644
--- a/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
+++ b/tools/testing/selftests/net/mptcp/mptcp_sockopt.c
@@ -726,6 +726,14 @@ static int xaccept(int s)
 	return fd;
 }
 
+static void do_setsockopt_inq(int fd)
+{
+	int on = 1;
+
+	if (-1 == setsockopt(fd, IPPROTO_TCP, TCP_INQ, &on, sizeof(on)))
+		die_perror("setsockopt(TCP_INQ)");
+}
+
 static int server(int ipcfd)
 {
 	int fd = -1, r;
@@ -748,6 +756,9 @@ static int server(int ipcfd)
 	alarm(15);
 	r = xaccept(fd);
 
+	if (inq)
+		do_setsockopt_inq(r);
+
 	process_one_client(r, ipcfd);
 
 	close(fd);
-- 
2.48.1