kselftest/arm64: Ensure stable names for GCS stress test results

The GCS stress test program currently uses the PID of the threads it
creates in the test names it reports, resulting in unstable test names
between runs. Fix this by using a thread number instead.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20241011-arm64-gcs-stress-stable-name-v1-1-4950f226218e@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Author: broonie

tools/testing/selftests/arm64/gcs/gcs-stress.c

@@ -56,7 +56,7 @@ static int num_processors(void)
 	return nproc;
 }
 
-static void start_thread(struct child_data *child)
+static void start_thread(struct child_data *child, int id)
 {
 	int ret, pipefd[2], i;
 	struct epoll_event ev;
@@ -132,7 +132,7 @@ static void start_thread(struct child_data *child)
 		ev.events = EPOLLIN | EPOLLHUP;
 		ev.data.ptr = child;
 
-		ret = asprintf(&child->name, "Thread-%d", child->pid);
+		ret = asprintf(&child->name, "Thread-%d", id);
 		if (ret == -1)
 			ksft_exit_fail_msg("asprintf() failed\n");
 
@@ -437,7 +437,7 @@ int main(int argc, char **argv)
 				   tests);
 
 	for (i = 0; i < gcs_threads; i++)
-		start_thread(&children[i]);
+		start_thread(&children[i], i);
 
 	/*
 	 * All children started, close the startup pipe and let them