This is a note to let you know that I've just added the patch titled
selftests/futex: Order calls to futex_lock_pi
to the 6.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
selftests-futex-order-calls-to-futex_lock_pi.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 47a4b2be1dca331a92820b10e6c424eb65821eec
Author: Nysal Jan K.A <nysal@xxxxxxxxxxxxx>
Date: Mon Aug 14 13:39:27 2023 +0530
selftests/futex: Order calls to futex_lock_pi
[ Upstream commit fbf4dec702774286db409815ffb077711a96b824 ]
Observed occassional failures in the futex_wait_timeout test:
ok 1 futex_wait relative succeeds
ok 2 futex_wait_bitset realtime succeeds
ok 3 futex_wait_bitset monotonic succeeds
ok 4 futex_wait_requeue_pi realtime succeeds
ok 5 futex_wait_requeue_pi monotonic succeeds
not ok 6 futex_lock_pi realtime returned 0
......
The test expects the child thread to complete some steps before
the parent thread gets to run. There is an implicit expectation
of the order of invocation of futex_lock_pi between the child thread
and the parent thread. Make this order explicit. If the order is
not met, the futex_lock_pi call in the parent thread succeeds and
will not timeout.
Fixes: f4addd54b161 ("selftests: futex: Expand timeout test")
Signed-off-by: Nysal Jan K.A <nysal@xxxxxxxxxxxxx>
Signed-off-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/tools/testing/selftests/futex/functional/futex_wait_timeout.c b/tools/testing/selftests/futex/functional/futex_wait_timeout.c
index 3651ce17beeb9..d183f878360bc 100644
--- a/tools/testing/selftests/futex/functional/futex_wait_timeout.c
+++ b/tools/testing/selftests/futex/functional/futex_wait_timeout.c
@@ -24,6 +24,7 @@
static long timeout_ns = 100000; /* 100us default timeout */
static futex_t futex_pi;
+static pthread_barrier_t barrier;
void usage(char *prog)
{
@@ -48,6 +49,8 @@ void *get_pi_lock(void *arg)
if (ret != 0)
error("futex_lock_pi failed\n", ret);
+ pthread_barrier_wait(&barrier);
+
/* Blocks forever */
ret = futex_wait(&lock, 0, NULL, 0);
error("futex_wait failed\n", ret);
@@ -130,6 +133,7 @@ int main(int argc, char *argv[])
basename(argv[0]));
ksft_print_msg("\tArguments: timeout=%ldns\n", timeout_ns);
+ pthread_barrier_init(&barrier, NULL, 2);
pthread_create(&thread, NULL, get_pi_lock, NULL);
/* initialize relative timeout */
@@ -163,6 +167,9 @@ int main(int argc, char *argv[])
res = futex_wait_requeue_pi(&f1, f1, &futex_pi, &to, 0);
test_timeout(res, &ret, "futex_wait_requeue_pi monotonic", ETIMEDOUT);
+ /* Wait until the other thread calls futex_lock_pi() */
+ pthread_barrier_wait(&barrier);
+ pthread_barrier_destroy(&barrier);
/*
* FUTEX_LOCK_PI with CLOCK_REALTIME
* Due to historical reasons, FUTEX_LOCK_PI supports only realtime
