[PATCH net] selftests: tls: make the new data_steal test less flaky

[PATCH net] selftests: tls: make the new data_steal test less flaky

[Jakub Kicinski]

The CI has hit a couple of cases of:

  RUN           global.data_steal ...
 tls.c:2762:data_steal:Expected recv(cfd, buf2, sizeof(buf2), MSG_DONTWAIT) (20000) == -1 (-1)
 data_steal: Test terminated by timeout
          FAIL  global.data_steal

Looks like the 2msec sleep is not long enough. Make the sleep longer,
and then instead of second sleep wait for the thieving process to exit.
That way we can be sure it called recv() before us.

While at it also avoid trying to steal more than a record, this seems
to be causing issues in manual testing as well.

Fixes: d7e82594a45c ("selftests: tls: test TCP stealing data from under the TLS socket")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 tools/testing/selftests/net/tls.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/net/tls.c b/tools/testing/selftests/net/tls.c
index dd82e198d21f..8df86ca630e0 100644
--- a/tools/testing/selftests/net/tls.c
+++ b/tools/testing/selftests/net/tls.c
@@ -2875,17 +2875,18 @@ TEST(data_steal) {
 	pid = fork();
 	ASSERT_GE(pid, 0);
 	if (!pid) {
-		EXPECT_EQ(recv(cfd, buf, sizeof(buf), MSG_WAITALL),
-			  sizeof(buf));
+		EXPECT_EQ(recv(cfd, buf, sizeof(buf) / 2, MSG_WAITALL),
+			  sizeof(buf) / 2);
 		exit(!__test_passed(_metadata));
 	}
 
-	usleep(2000);
+	usleep(10000);
 	ASSERT_EQ(setsockopt(fd, SOL_TLS, TLS_TX, &tls, tls.len), 0);
 	ASSERT_EQ(setsockopt(cfd, SOL_TLS, TLS_RX, &tls, tls.len), 0);
 
 	EXPECT_EQ(send(fd, buf, sizeof(buf), 0), sizeof(buf));
-	usleep(2000);
+	EXPECT_EQ(wait(&status), pid);
+	EXPECT_EQ(status, 0);
 	EXPECT_EQ(recv(cfd, buf2, sizeof(buf2), MSG_DONTWAIT), -1);
 	/* Don't check errno, the error will be different depending
 	 * on what random bytes TLS interpreted as the record length.
@@ -2893,9 +2894,6 @@ TEST(data_steal) {
 
 	close(fd);
 	close(cfd);
-
-	EXPECT_EQ(wait(&status), pid);
-	EXPECT_EQ(status, 0);
 }
 
 static void __attribute__((constructor)) fips_check(void) {
-- 
2.50.1

Re: [PATCH net] selftests: tls: make the new data_steal test less flaky

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Thu, 14 Aug 2025 12:43:23 -0700 you wrote:
> The CI has hit a couple of cases of:
> 
>   RUN           global.data_steal ...
>  tls.c:2762:data_steal:Expected recv(cfd, buf2, sizeof(buf2), MSG_DONTWAIT) (20000) == -1 (-1)
>  data_steal: Test terminated by timeout
>           FAIL  global.data_steal
> 
> [...]

Here is the summary with links:
  - [net] selftests: tls: make the new data_steal test less flaky
    https://git.kernel.org/netdev/net/c/715c7a36d59f

You are awesome, thank you!
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