selftests: pidfd: do not use ksft_exit_skip after ksft_set_plan

Calling ksft_exit_skip after ksft_set_plan results in executing fewer tests
than planned.  Use ksft_test_result_skip instead.

The plan passed to ksft_set_plan was wrong, too, so fix it while at it.
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/pidfd/pidfd_test.c

@@ -8,6 +8,7 @@
 #include <sched.h>
 #include <signal.h>
 #include <stdio.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
 #include <syscall.h>
@@ -27,6 +28,8 @@
 
 #define MAX_EVENTS 5
 
+static bool have_pidfd_send_signal;
+
 static pid_t pidfd_clone(int flags, int *pidfd, int (*fn)(void *))
 {
 	size_t stack_size = 1024;
@@ -56,6 +59,13 @@ static int test_pidfd_send_signal_simple_success(void)
 	int pidfd, ret;
 	const char *test_name = "pidfd_send_signal send SIGUSR1";
 
+	if (!have_pidfd_send_signal) {
+		ksft_test_result_skip(
+			"%s test: pidfd_send_signal() syscall not supported\n",
+			test_name);
+		return 0;
+	}
+
 	pidfd = open("/proc/self", O_DIRECTORY | O_CLOEXEC);
 	if (pidfd < 0)
 		ksft_exit_fail_msg(
@@ -86,6 +96,13 @@ static int test_pidfd_send_signal_exited_fail(void)
 	pid_t pid;
 	const char *test_name = "pidfd_send_signal signal exited process";
 
+	if (!have_pidfd_send_signal) {
+		ksft_test_result_skip(
+			"%s test: pidfd_send_signal() syscall not supported\n",
+			test_name);
+		return 0;
+	}
+
 	pid = fork();
 	if (pid < 0)
 		ksft_exit_fail_msg("%s test: Failed to create new process\n",
@@ -137,6 +154,13 @@ static int test_pidfd_send_signal_recycled_pid_fail(void)
 	pid_t pid1;
 	const char *test_name = "pidfd_send_signal signal recycled pid";
 
+	if (!have_pidfd_send_signal) {
+		ksft_test_result_skip(
+			"%s test: pidfd_send_signal() syscall not supported\n",
+			test_name);
+		return 0;
+	}
+
 	ret = unshare(CLONE_NEWPID);
 	if (ret < 0)
 		ksft_exit_fail_msg("%s test: Failed to unshare pid namespace\n",
@@ -325,15 +349,17 @@ static int test_pidfd_send_signal_syscall_support(void)
 
 	ret = sys_pidfd_send_signal(pidfd, 0, NULL, 0);
 	if (ret < 0) {
-		if (errno == ENOSYS)
-			ksft_exit_skip(
+		if (errno == ENOSYS) {
+			ksft_test_result_skip(
 				"%s test: pidfd_send_signal() syscall not supported\n",
 				test_name);
-
+			return 0;
+		}
 		ksft_exit_fail_msg("%s test: Failed to send signal\n",
 				   test_name);
 	}
 
+	have_pidfd_send_signal = true;
 	close(pidfd);
 	ksft_test_result_pass(
 		"%s test: pidfd_send_signal() syscall is supported. Tests can be executed\n",
@@ -521,7 +547,7 @@ static void test_pidfd_poll_leader_exit(int use_waitpid)
 int main(int argc, char **argv)
 {
 	ksft_print_header();
-	ksft_set_plan(4);
+	ksft_set_plan(8);
 
 	test_pidfd_poll_exec(0);
 	test_pidfd_poll_exec(1);