[PATCH mptcp-next v12 2/5] selftests/bpf: Use random netns name for mptcp

[Geliang Tang]

When running mptcp tests simultaneously, it fails sometimes with
"Cannot create namespace file "/var/run/netns/mptcp_ns": File exists"
errors. So this patch uses rand() to generate a random netns name
instead of using the fixed name "mptcp_ns" for every test.

Add "ip netns show" after "ip netns del" to check if there is a test
did not clean up its netns

By doing that, we can re-launch the test even if there was an issue
removing the previous netns or if by accident, a netns with this
generic name already existed on the system.

Note that using a different name each will also help adding more
subtests in future commits.

Acked-by: Yonghong Song <yonghong.song at linux.dev>
Reviewed-by: Matthieu Baerts <matthieu.baerts at tessares.net>
Signed-off-by: Geliang Tang <geliang.tang at suse.com>
---
 tools/testing/selftests/bpf/prog_tests/mptcp.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/mptcp.c b/tools/testing/selftests/bpf/prog_tests/mptcp.c
index cd0c42fff7c0..b2d41024c6c2 100644
--- a/tools/testing/selftests/bpf/prog_tests/mptcp.c
+++ b/tools/testing/selftests/bpf/prog_tests/mptcp.c
@@ -7,7 +7,7 @@
 #include "network_helpers.h"
 #include "mptcp_sock.skel.h"
 
-#define NS_TEST "mptcp_ns"
+char NS_TEST[32];
 
 #ifndef TCP_CA_NAME_MAX
 #define TCP_CA_NAME_MAX	16
@@ -147,6 +147,8 @@ static void test_base(void)
 	if (!ASSERT_GE(cgroup_fd, 0, "test__join_cgroup"))
 		return;
 
+	srand(time(NULL));
+	snprintf(NS_TEST, sizeof(NS_TEST), "mptcp_ns_%d", rand());
 	SYS(fail, "ip netns add %s", NS_TEST);
 	SYS(fail, "ip -net %s link set dev lo up", NS_TEST);
 
@@ -178,6 +180,7 @@ static void test_base(void)
 		close_netns(nstoken);
 
 	SYS_NOFAIL("ip netns del " NS_TEST " &> /dev/null");
+	SYS_NOFAIL("ip netns show %s", NS_TEST);
 
 	close(cgroup_fd);
 }
-- 
2.35.3