[LTP] [PATCH] futex/futex_wake04.c: fix issues with hugepages and usleep

[Rafael David Tinoco]

This commit fixes 2 observed issues:

1) usleep() time is too small if test is being executed in slower
terminal devices (specially embedded systems). Raising it to 0.001
seconds was enough to finish 10240 iterations in around 90 seconds in a
4 vcpu kvm guest (fully emulated serial being used as console).

2) Test was changing number of hugepages during setup()/cleanup() phase
despite the system had (or not) available hugepages. This was causing
overhead of destroying (or creating) hugepages during the test
execution.  Now, if system has > 0 hugepages available, the test doesn't
touch it.

Link: https://bugs.linaro.org/show_bug.cgi?id=3984
Signed-off-by: Rafael David Tinoco <rafael.tinoco@linaro.org>
---
 testcases/kernel/syscalls/futex/futex_wake04.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/testcases/kernel/syscalls/futex/futex_wake04.c b/testcases/kernel/syscalls/futex/futex_wake04.c
index 3c7038317..93d36ac33 100644
--- a/testcases/kernel/syscalls/futex/futex_wake04.c
+++ b/testcases/kernel/syscalls/futex/futex_wake04.c
@@ -76,14 +76,17 @@ static void setup(void)
 	tst_tmpdir();
 
 	SAFE_FILE_SCANF(NULL, PATH_NR_HUGEPAGES, "%ld", &orig_hugepages);
-	SAFE_FILE_PRINTF(NULL, PATH_NR_HUGEPAGES, "%d", 1);
+
+	if (!orig_hugepages)
+		SAFE_FILE_PRINTF(NULL, PATH_NR_HUGEPAGES, "%d", 1);
 
 	TEST_PAUSE;
 }
 
 static void cleanup(void)
 {
-	SAFE_FILE_PRINTF(NULL, PATH_NR_HUGEPAGES, "%ld", orig_hugepages);
+	if (!orig_hugepages)
+		SAFE_FILE_PRINTF(NULL, PATH_NR_HUGEPAGES, "%d", 0);
 
 	tst_rmdir();
 }
@@ -172,8 +175,9 @@ static void wakeup_thread2(void)
 				tst_strerrno(res));
 	}
 
+	/* 0.001 seconds: less might cause lockups for slower terminals */
 	while (wait_for_threads(2))
-		usleep(100);
+		usleep(1000);
 
 	futex_wake(futex2, 1, 0);
 
-- 
2.19.1