[LTP] [PATCH] syscalls/futex_waitv03: replace TST_THREAD_STATE_WAIT with repeated wake

[Jan Stancek]

TST_THREAD_STATE_WAIT isn't reliable to tell that it's safe to call futex_wake().
futex_wake() can be called prematurely and return 0, which leaves other thread
timing out on futex call:
  tst_test.c:1459: TINFO: Timeout per run is 0h 10m 00s
  futex_waitv03.c:37: TINFO: Testing variant: syscall with old kernel spec
  tst_buffers.c:55: TINFO: Test is using guarded buffers
  futex_waitv03.c:106: TBROK: futex_waitv returned: -1: ETIMEDOUT (110)

Replace it with repeated futex_wake() until it fails or wakes at least 1 waiter.
Also extend timeout to 5 seconds to avoid false positives from systems with
high steal time (e.g. overloaded s390x host).

Signed-off-by: Jan Stancek <jstancek@redhat.com>
---
 .../kernel/syscalls/futex/futex_waitv03.c     | 25 ++++++++-----------
 1 file changed, 11 insertions(+), 14 deletions(-)

diff --git a/testcases/kernel/syscalls/futex/futex_waitv03.c b/testcases/kernel/syscalls/futex/futex_waitv03.c
index ffe5c66cde77..ee79728474ee 100644
--- a/testcases/kernel/syscalls/futex/futex_waitv03.c
+++ b/testcases/kernel/syscalls/futex/futex_waitv03.c
@@ -70,19 +70,19 @@ static void cleanup(void)
 	}
 }
 
-static void *threaded(void *arg)
+static void *threaded(LTP_ATTRIBUTE_UNUSED void *arg)
 {
 	struct futex_test_variants tv = futex_variant();
-	int tid = *(int *)arg;
 
-	TST_THREAD_STATE_WAIT(tid, 'S', 0);
-
-	TEST(futex_wake(tv.fntype, (void *)(uintptr_t)waitv[numfutex - 1].uaddr,
+	do {
+		TEST(futex_wake(tv.fntype, (void *)(uintptr_t)waitv[numfutex - 1].uaddr,
 			1, 0));
-	if (TST_RET < 0) {
-		tst_brk(TBROK | TTERRNO,
-			"futex_wake private returned: %ld", TST_RET);
-	}
+		if (TST_RET < 0) {
+			tst_brk(TBROK | TTERRNO,
+				"futex_wake private returned: %ld", TST_RET);
+		}
+		usleep(1000);
+	} while (TST_RET < 1);
 
 	return NULL;
 }
@@ -90,16 +90,13 @@ static void *threaded(void *arg)
 static void run(void)
 {
 	struct timespec to;
-	int tid;
 	pthread_t t;
 
-	tid = tst_syscall(__NR_gettid);
-
-	SAFE_PTHREAD_CREATE(&t, NULL, threaded, (void *)&tid);
+	SAFE_PTHREAD_CREATE(&t, NULL, threaded, NULL);
 
 	/* setting absolute timeout for futex2 */
 	SAFE_CLOCK_GETTIME(CLOCK_MONOTONIC, &to);
-	to.tv_sec++;
+	to.tv_sec += 5;
 
 	TEST(futex_waitv(waitv, numfutex, 0, &to, CLOCK_MONOTONIC));
 	if (TST_RET < 0) {
-- 
2.27.0