[LTP] [PATCH 1/2] checkpoints: avoid unnecesasry sleep in checkpoint_wake

[Jan Stancek]

checkpoint_wake is currently sleeping also in case when
it wakes up all processes. This creates problem for combination
of checkpoints and process_state_wait, because it creates
false impression, that child is sleeping on operation
following checkpoint_wake (#2), while it really sleeps inside
checkpoint_wake (#1).

      child                      parent
TST_CHECKPOINT_WAKE #1
                               TST_CHECKPOINT_WAIT
                               TST_PROCESS_STATE_WAIT(child, 'S')
                               kill(child, SIGINT)
sleep() #2

This patch avoids sleep in checkpoint_wake if all processes has been
already woken up.

Signed-off-by: Jan Stancek <jstancek@redhat.com>
---
 lib/tst_checkpoint.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/tst_checkpoint.c b/lib/tst_checkpoint.c
index 8f23ead26a8a..128e658153c6 100644
--- a/lib/tst_checkpoint.c
+++ b/lib/tst_checkpoint.c
@@ -109,6 +109,10 @@ int tst_checkpoint_wake(unsigned int id, unsigned int nr_wake,
 	do {
 		waked += syscall(SYS_futex, &tst_futexes[id], FUTEX_WAKE,
 				 INT_MAX, NULL);
+
+		if (waked == nr_wake)
+			break;
+
 		usleep(1000);
 		msecs++;
 
-- 
1.8.3.1