[PATCH net-next v4 4/8] selftests/net: Open /proc/thread-self in open_netns()

Dmitry Safonov via B4 Relay
2024-08-23T22:05:18Z

It turns to be that open_netns() is called rarely from the child-thread
and more often from parent-thread. Yet, on initialization of kconfig
checks, either of threads may reach kconfig_lock mutex first.
VRF-related checks do create a temporary ksft-check VRF in
an unshare()'d namespace and than setns() back to the original.
As original was opened from "/proc/self/ns/net", it's valid for
thread-leader (parent), but it's invalid for the child, resulting
in the following failure on tests that check has_vrfs() support:
> # ok 54 TCP-AO required on socket + TCP-MD5 key: prefailed as expected: Key was rejected by service
> # not ok 55 # error 381[unsigned-md5.c:24] Failed to add a VRF: -17
> # not ok 56 # error 383[unsigned-md5.c:33] Failed to add a route to VRF: -22: Key was rejected by service
> not ok 1 selftests: net/tcp_ao: unsigned-md5_ipv6 # exit=1

Use "/proc/thread-self/ns/net" which is valid for any thread.

Signed-off-by: Dmitry Safonov <0x7f454c46@gmail.com>
---
tools/testing/selftests/net/tcp_ao/lib/setup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/net/tcp_ao/lib/setup.c b/tools/testing/selftests/net/tcp_ao/lib/setup.c
index e408b9243b2c..d5212ffe9489 100644
--- a/tools/testing/selftests/net/tcp_ao/lib/setup.c
+++ b/tools/testing/selftests/net/tcp_ao/lib/setup.c
@@ -111,7 +111,7 @@ static void sig_int(int signo)

int open_netns(void)
{
- const char *netns_path = "/proc/self/ns/net";
+ const char *netns_path = "/proc/thread-self/ns/net";
int fd;

fd = open(netns_path, O_RDONLY);

--
2.42.2