selftests: tls: make the new data_steal test less flaky

JIRA: https://issues.redhat.com/browse/RHEL-115640

commit 715c7a3
Author: Jakub Kicinski <kuba@kernel.org>
Date:   Thu Aug 14 12:43:23 2025 -0700

    selftests: tls: make the new data_steal test less flaky

    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: d7e8259 ("selftests: tls: test TCP stealing data from under the TLS socket")
    Link: https://patch.msgid.link/20250814194323.2014650-1-kuba@kernel.org
    Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Signed-off-by: Sabrina Dubroca <sdubroca@redhat.com>

Author: Sabrina Dubroca

tools/testing/selftests/net/tls.c

@@ -2526,27 +2526,25 @@ 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.
 	 */
 
 	close(fd);
 	close(cfd);
-
-	EXPECT_EQ(wait(&status), pid);
-	EXPECT_EQ(status, 0);
 }
 
 static void __attribute__((constructor)) fips_check(void) {