[PATCH v4 4/5] 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 there is
an error occurs or such as a SIGINT signal is received, the parent
process will be terminated immediately, but the child process will not
be killed and also umount_resctrlfs() will not be called.

Add a signal handler like other tests to kill child process, umount
resctrlfs, cleanup result files, etc. if an error occurs in parent
process. To use ctrlc_handler() of other tests to kill child
process(bm_pid), using global bm_pid instead of local bm_pid.

Wait for child process to be killed if an error occurs in child process.

Reviewed-by: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Shaopeng Tan <tan.shaopeng@xxxxxxxxxxxxxx>
---
 tools/testing/selftests/resctrl/cat_test.c | 30 ++++++++++++++--------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/resctrl/cat_test.c b/tools/testing/selftests/resctrl/cat_test.c
index 6a8306b0a109..1f8f5cf94e95 100644
--- a/tools/testing/selftests/resctrl/cat_test.c
+++ b/tools/testing/selftests/resctrl/cat_test.c
@@ -100,10 +100,10 @@ void cat_test_cleanup(void)
 
 int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
 {
+	struct sigaction sigact;
 	unsigned long l_mask, l_mask_1;
 	int ret, pipefd[2], sibling_cpu_no;
 	char pipe_message;
-	pid_t bm_pid;
 
 	cache_size = 0;
 
@@ -181,17 +181,25 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
 		strcpy(param.filename, RESULT_FILE_NAME1);
 		param.num_of_runs = 0;
 		param.cpu_no = sibling_cpu_no;
+	} else {
+		/*
+		 * Register CTRL-C handler for parent, as it has to kill
+		 * child process before exiting
+		 */
+		sigact.sa_sigaction = ctrlc_handler;
+		sigemptyset(&sigact.sa_mask);
+		sigact.sa_flags = SA_SIGINFO;
+		if (sigaction(SIGINT, &sigact, NULL) ||
+		    sigaction(SIGTERM, &sigact, NULL) ||
+		    sigaction(SIGHUP, &sigact, NULL))
+			perror("# sigaction");
 	}
 
 	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 */
@@ -199,9 +207,11 @@ int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
 		pipe_message = 1;
 		if (write(pipefd[1], &pipe_message, sizeof(pipe_message)) <
 		    sizeof(pipe_message)) {
-			close(pipefd[1]);
+			/*
+			 * 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]);
@@ -226,5 +236,5 @@ 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