[PATCH net-next v2] selftests: tls: use mkstemp instead of open(O_TMPFILE)

[PATCH net-next v2] selftests: tls: use mkstemp instead of open(O_TMPFILE)

[Geliang Tang]

From: Gang Yan <yangang@kylinos.cn>

When running TLS tests in a virtual machine/container environment, they
fail in test_mutliproc():

 # tls.c:1479:mutliproc_even: Expected fd (-1) >= 0 (0)
 # mutliproc_even: Test terminated by assertion
 #          FAIL  tls.12_aes_gcm.mutliproc_even
 not ok 59 tls.12_aes_gcm.mutliproc_even
 #  RUN           tls.12_aes_gcm.mutliproc_readers ...
 # tls.c:1479:mutliproc_readers: Expected fd (-1) >= 0 (0)
 # mutliproc_readers: Test terminated by assertion
 #          FAIL  tls.12_aes_gcm.mutliproc_readers
 not ok 60 tls.12_aes_gcm.mutliproc_readers
 #  RUN           tls.12_aes_gcm.mutliproc_writers ...
 # tls.c:1479:mutliproc_writers: Expected fd (-1) >= 0 (0)
 # mutliproc_writers: Test terminated by assertion
 #          FAIL  tls.12_aes_gcm.mutliproc_writers
 not ok 61 tls.12_aes_gcm.mutliproc_writers

This is because the /tmp directory uses the virtiofs filesystem, which does
not support the O_TMPFILE feature.

This patch uses mkstemp() to create temporary files, just like the approach
used in chunked_sendfile(), thereby eliminating the dependency on the
O_TMPFILE feature.

For better code reuse, factor out this code from chunked_sendfile() into a
separate helper create_temp_file(). Use this new heler in test_mutliproc()
and closes the file descriptor (fd) after the test ends.

Co-developed-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Geliang Tang <geliang@kernel.org>
Signed-off-by: Gang Yan <yangang@kylinos.cn>
---
v2:
 - factor out a new helper, use it in both chunked_sendfile() and
   test_mutliproc().
---
 tools/testing/selftests/net/tls.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/net/tls.c b/tools/testing/selftests/net/tls.c
index 9e2ccea13d70..2eaacb7f2e56 100644
--- a/tools/testing/selftests/net/tls.c
+++ b/tools/testing/selftests/net/tls.c
@@ -467,6 +467,15 @@ TEST_F(tls, send_then_sendfile)
 	close(filefd);
 }
 
+static int create_temp_file(void)
+{
+	char filename[] = "/tmp/mytemp.XXXXXX";
+	int fd = mkstemp(filename);
+
+	unlink(filename);
+	return fd;
+}
+
 static void chunked_sendfile(struct __test_metadata *_metadata,
 			     struct _test_data_tls *self,
 			     uint16_t chunk_size,
@@ -476,11 +485,9 @@ static void chunked_sendfile(struct __test_metadata *_metadata,
 	uint16_t test_payload_size;
 	int size = 0;
 	int ret;
-	char filename[] = "/tmp/mytemp.XXXXXX";
-	int fd = mkstemp(filename);
+	int fd = create_temp_file();
 	off_t offset = 0;
 
-	unlink(filename);
 	ASSERT_GE(fd, 0);
 	EXPECT_GE(chunk_size, 1);
 	test_payload_size = chunk_size + extra_payload_size;
@@ -1469,7 +1476,7 @@ test_mutliproc(struct __test_metadata *_metadata, struct _test_data_tls *self,
 	write_bias = n_readers / n_writers ?: 1;
 
 	/* prep a file to send */
-	fd = open("/tmp/", O_TMPFILE | O_RDWR, 0600);
+	fd = create_temp_file();
 	ASSERT_GE(fd, 0);
 
 	memset(buf, 0xac, file_sz);
@@ -1527,6 +1534,7 @@ test_mutliproc(struct __test_metadata *_metadata, struct _test_data_tls *self,
 			left -= res;
 		}
 	}
+	close(fd);
 }
 
 TEST_F(tls, mutliproc_even)
-- 
2.51.0

Re: [PATCH net-next v2] selftests: tls: use mkstemp instead of open(O_TMPFILE)

[Jakub Kicinski]

On Thu, 15 Jan 2026 17:02:40 +0800 Geliang Tang wrote:
> This is because the /tmp directory uses the virtiofs filesystem, which does
> not support the O_TMPFILE feature.

I don't think selftests are expected to support setups where /tmp 
isn't tmp. Please fix your setup instead (or explain why it's very
crucial that you don't). The upstream CI runs all the selftests in
VMs and they are working just fine.
-- 
pw-bot: reject

Re: [PATCH net-next v2] selftests: tls: use mkstemp instead of open(O_TMPFILE)

[Geliang Tang]

Hi Jakub, Matt,

On Thu, 2026-01-15 at 18:49 -0800, Jakub Kicinski wrote:
> On Thu, 15 Jan 2026 17:02:40 +0800 Geliang Tang wrote:
> > This is because the /tmp directory uses the virtiofs filesystem,
> > which does
> > not support the O_TMPFILE feature.
> 
> I don't think selftests are expected to support setups where /tmp 
> isn't tmp. Please fix your setup instead (or explain why it's very

Thanks for reviewing. I recently implemented TLS support for MPTCP and
have been adding MPTCP test items to the TLS selftests. When running
these in the MPTCP upstream CI (mptcp-upstream-virtme-docker), these
O_TMPFILE unsupported errors occurred.

Following your suggestion, I looked into the mptcp-upstream-virtme-
docker configuration and found that /tmp isn't mounted as tmpfs; it's
just a plain directory. I've opened a PR to address this:

virtme: mount /tmp as overlay for O_TMPFILE support

https://github.com/multipath-tcp/mptcp-upstream-virtme-docker/pull/43

@Matt

This change adds "--overlay-rwdir /tmp" to virtme-run options, ensuring
/tmp gets mounted as an overlay filesystem. It functions correctly,
though I'm not certain it's the ideal solution.

Thanks,
-Geliang

> crucial that you don't). The upstream CI runs all the selftests in
> VMs and they are working just fine.