[PATCH v2 2/3] selftests: coredump: Fix test failure for slow machines

[Nam Cao <namcao@linutronix.de>]

The test waits for coredump to finish by busy-waiting for the stack_values
file to be created. The maximum wait time is 10 seconds.

This doesn't work for slow machine (qemu-system-riscv64), because coredump
takes longer.

Fix it by waiting for the crashing child process to finish first.

Fixes: 15858da53542 ("selftests: coredump: Add stackdump test")
Signed-off-by: Nam Cao <namcao@linutronix.de>
---
 tools/testing/selftests/coredump/stackdump_test.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/coredump/stackdump_test.c b/tools/testing/selftests/coredump/stackdump_test.c
index c23cf95c3f6d..9da10fb5e597 100644
--- a/tools/testing/selftests/coredump/stackdump_test.c
+++ b/tools/testing/selftests/coredump/stackdump_test.c
@@ -96,7 +96,7 @@ TEST_F(coredump, stackdump)
 	char *test_dir, *line;
 	size_t line_length;
 	char buf[PATH_MAX];
-	int ret, i;
+	int ret, i, status;
 	FILE *file;
 	pid_t pid;
 
@@ -129,6 +129,10 @@ TEST_F(coredump, stackdump)
 	/*
 	 * Step 3: Wait for the stackdump script to write the stack pointers to the stackdump file
 	 */
+	waitpid(pid, &status, 0);
+	ASSERT_TRUE(WIFSIGNALED(status));
+	ASSERT_TRUE(WCOREDUMP(status));
+
 	for (i = 0; i < 10; ++i) {
 		file = fopen(STACKDUMP_FILE, "r");
 		if (file)
-- 
2.39.5