selftests/harness: Move test child waiting logic

In order to better handle timeout failures, rearrange the child waiting
logic into a separate function. This is mostly a copy/paste with an
indentation change. To handle pid tracking, a new field is added for
the child pid. Also move the alarm() pairing into the function.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/kselftest_harness.h

@@ -635,6 +635,7 @@
 struct __test_metadata {
 	const char *name;
 	void (*fn)(struct __test_metadata *);
+	pid_t pid;	/* pid of test when being run */
 	int termsig;
 	int passed;
 	int trigger; /* extra handler after the evaluation */
@@ -695,64 +696,68 @@ static inline int __bail(int for_realz, bool no_print, __u8 step)
 	return 0;
 }
 
-void __run_test(struct __test_metadata *t)
+void __wait_for_test(struct __test_metadata *t)
 {
-	pid_t child_pid;
 	int status;
 
+	alarm(t->timeout);
+	waitpid(t->pid, &status, 0);
+	alarm(0);
+
+	if (WIFEXITED(status)) {
+		t->passed = t->termsig == -1 ? !WEXITSTATUS(status) : 0;
+		if (t->termsig != -1) {
+			fprintf(TH_LOG_STREAM,
+				"%s: Test exited normally "
+				"instead of by signal (code: %d)\n",
+				t->name,
+				WEXITSTATUS(status));
+		} else if (!t->passed) {
+			fprintf(TH_LOG_STREAM,
+				"%s: Test failed at step #%d\n",
+				t->name,
+				WEXITSTATUS(status));
+		}
+	} else if (WIFSIGNALED(status)) {
+		t->passed = 0;
+		if (WTERMSIG(status) == SIGABRT) {
+			fprintf(TH_LOG_STREAM,
+				"%s: Test terminated by assertion\n",
+				t->name);
+		} else if (WTERMSIG(status) == t->termsig) {
+			t->passed = 1;
+		} else {
+			fprintf(TH_LOG_STREAM,
+				"%s: Test terminated unexpectedly "
+				"by signal %d\n",
+				t->name,
+				WTERMSIG(status));
+		}
+	} else {
+		fprintf(TH_LOG_STREAM,
+			"%s: Test ended in some other way [%u]\n",
+			t->name,
+			status);
+	}
+}
+
+void __run_test(struct __test_metadata *t)
+{
 	t->passed = 1;
 	t->trigger = 0;
 	printf("[ RUN      ] %s\n", t->name);
-	alarm(t->timeout);
-	child_pid = fork();
-	if (child_pid < 0) {
+	t->pid = fork();
+	if (t->pid < 0) {
 		printf("ERROR SPAWNING TEST CHILD\n");
 		t->passed = 0;
-	} else if (child_pid == 0) {
+	} else if (t->pid == 0) {
 		t->fn(t);
 		/* return the step that failed or 0 */
 		_exit(t->passed ? 0 : t->step);
 	} else {
-		/* TODO(wad) add timeout support. */
-		waitpid(child_pid, &status, 0);
-		if (WIFEXITED(status)) {
-			t->passed = t->termsig == -1 ? !WEXITSTATUS(status) : 0;
-			if (t->termsig != -1) {
-				fprintf(TH_LOG_STREAM,
-					"%s: Test exited normally "
-					"instead of by signal (code: %d)\n",
-					t->name,
-					WEXITSTATUS(status));
-			} else if (!t->passed) {
-				fprintf(TH_LOG_STREAM,
-					"%s: Test failed at step #%d\n",
-					t->name,
-					WEXITSTATUS(status));
-			}
-		} else if (WIFSIGNALED(status)) {
-			t->passed = 0;
-			if (WTERMSIG(status) == SIGABRT) {
-				fprintf(TH_LOG_STREAM,
-					"%s: Test terminated by assertion\n",
-					t->name);
-			} else if (WTERMSIG(status) == t->termsig) {
-				t->passed = 1;
-			} else {
-				fprintf(TH_LOG_STREAM,
-					"%s: Test terminated unexpectedly "
-					"by signal %d\n",
-					t->name,
-					WTERMSIG(status));
-			}
-		} else {
-			fprintf(TH_LOG_STREAM,
-				"%s: Test ended in some other way [%u]\n",
-				t->name,
-				status);
-		}
+		__wait_for_test(t);
 	}
 	printf("[     %4s ] %s\n", (t->passed ? "OK" : "FAIL"), t->name);
-	alarm(0);
 }
 
 static int test_harness_run(int __attribute__((unused)) argc,