From: Geliang Tang <tanggeliang@kylinos.cn>

In order to prevent mptcpify prog from affecting the running results
of other BPF tests, a pid limit was added to restrict it from only
modifying its own program.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Suggested-by: Martin KaFai Lau <martin.lau@kernel.org>
---
 tools/testing/selftests/bpf/prog_tests/mptcp.c | 2 ++
 tools/testing/selftests/bpf/progs/mptcpify.c   | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/mptcp.c b/tools/testing/selftests/bpf/prog_tests/mptcp.c
index bff13ecec64c..17f352154994 100644
--- a/tools/testing/selftests/bpf/prog_tests/mptcp.c
+++ b/tools/testing/selftests/bpf/prog_tests/mptcp.c
@@ -266,6 +266,8 @@ static int run_mptcpify(int cgroup_fd)
 	if (!ASSERT_OK_PTR(mptcpify_skel, "skel_open_load"))
 		return libbpf_get_error(mptcpify_skel);
 
+	mptcpify_skel->bss->pid = getpid();
+
 	err = mptcpify__attach(mptcpify_skel);
 	if (!ASSERT_OK(err, "skel_attach"))
 		goto out;
diff --git a/tools/testing/selftests/bpf/progs/mptcpify.c b/tools/testing/selftests/bpf/progs/mptcpify.c
index 53301ae8a8f7..cbdc730c3a47 100644
--- a/tools/testing/selftests/bpf/progs/mptcpify.c
+++ b/tools/testing/selftests/bpf/progs/mptcpify.c
@@ -6,10 +6,14 @@
 #include "bpf_tracing_net.h"
 
 char _license[] SEC("license") = "GPL";
+int pid;
 
 SEC("fmod_ret/update_socket_protocol")
 int BPF_PROG(mptcpify, int family, int type, int protocol)
 {
+	if (bpf_get_current_pid_tgid() >> 32 != pid)
+		return protocol;
+
 	if ((family == AF_INET || family == AF_INET6) &&
 	    type == SOCK_STREAM &&
 	    (!protocol || protocol == IPPROTO_TCP)) {
-- 
2.40.1