[PATCH v7 4/6] selftests/resctrl: Cleanup properly when an error occurs in CAT test

[Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>]

After creating a child process with fork() in CAT test, if an error
occurs when parent process runs cat_val() or check_results(), the child
process will not be killed and also resctrlfs is not unmounted. Also if
an error occurs when child process runs cat_val() or check_results(),
the child process is returned, but the parent process will wait pipe
message from child.

Synchronize the exits between the parent and child. An error occurs
whether in parents process or child process, the parents process
always kills child process and runs umount_resctrlfs(), and the
child process always waits to be killed by the parent process.

Signed-off-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
---
 tools/testing/selftests/resctrl/cat_test.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
index 6a8306b0a109..477b62dac546 100644
--- a/tools/testing/selftests/resctrl/cat_test.c
+++ b/tools/testing/selftests/resctrl/cat_test.c
@@ -186,23 +186,20 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
 	remove(param.filename);
 
 	ret = cat_val(&param);
-	if (ret)
-		return ret;
-
-	ret = check_results(&param);
-	if (ret)
-		return ret;
+	if (ret == 0)
+		ret = check_results(&param);
 
 	if (bm_pid == 0) {
 		/* Tell parent that child is ready */
 		close(pipefd[0]);
 		pipe_message = 1;
 		if (write(pipefd[1], &pipe_message, sizeof(pipe_message)) <
-		    sizeof(pipe_message)) {
-			close(pipefd[1]);
+		    sizeof(pipe_message))
+			/*
+			 * Just print the error message.
+			 * Let while(1) run and wait for itself to be killed.
+			 */
 			perror("# failed signaling parent process");
-			return errno;
-		}
 
 		close(pipefd[1]);
 		while (1)
@@ -226,5 +223,5 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
 	if (bm_pid)
 		umount_resctrlfs();
 
-	return 0;
+	return ret;
 }
-- 
2.27.0