syscalls/tgkill02: add new test

tgkill() should fail with EAGAIN when RLIMIT_SIGPENDING is reached with
a real-time signal.  Test this by starting a child thread with SIGRTMIN
blocked and a limit of 0 pending signals, then attempting to deliver
SIGRTMIN from the parent thread.

Signed-off-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Li Wang <liwang@redhat.com>
Acked-by: Cyril Hrubis <chrubis@suse.cz>

2 files changed, 69 insertions, 0 deletions

diff --git a/testcases/kernel/syscalls/tgkill/.gitignore b/testcases/kernel/syscalls/tgkill/.gitignore
index f4566fde2..42be2bb0b 100644
--- a/testcases/kernel/syscalls/tgkill/.gitignore
+++ b/testcases/kernel/syscalls/tgkill/.gitignore
@@ -1 +1,2 @@
 tgkill01
+tgkill02
diff --git a/testcases/kernel/syscalls/tgkill/tgkill02.c b/testcases/kernel/syscalls/tgkill/tgkill02.c
new file mode 100644
index 000000000..88f384288
--- /dev/null
+++ b/testcases/kernel/syscalls/tgkill/tgkill02.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2018 Google, Inc.
+ *
+ * tgkill() should fail with EAGAIN when RLIMIT_SIGPENDING is reached with a
+ * real-time signal.  Test this by starting a child thread with SIGRTMIN
+ * blocked and a limit of 0 pending signals, then attempting to deliver
+ * SIGRTMIN from the parent thread.
+ */
+
+#include <pthread.h>
+#include <signal.h>
+
+#include "tst_safe_pthread.h"
+#include "tst_test.h"
+#include "tgkill.h"
+
+static void *thread_func(void *arg)
+{
+	const struct rlimit sigpending = {
+		.rlim_cur = 0,
+		.rlim_max = 0,
+	};
+	sigset_t sigrtmin;
+	int err;
+	pid_t *tid = arg;
+
+	sigemptyset(&sigrtmin);
+	sigaddset(&sigrtmin, SIGRTMIN);
+
+	err = pthread_sigmask(SIG_BLOCK, &sigrtmin, NULL);
+	if (err)
+		tst_brk(TBROK, "pthread_sigmask() failed: %s",
+			tst_strerrno(err));
+
+	SAFE_SETRLIMIT(RLIMIT_SIGPENDING, &sigpending);
+	*tid = sys_gettid();
+
+	TST_CHECKPOINT_WAKE_AND_WAIT(0);
+
+	return arg;
+}
+
+static void run(void)
+{
+	pthread_t thread;
+	pid_t tid = -1;
+
+	SAFE_PTHREAD_CREATE(&thread, NULL, thread_func, &tid);
+
+	TST_CHECKPOINT_WAIT(0);
+
+	TEST(sys_tgkill(getpid(), tid, SIGRTMIN));
+	if (TST_RET && TST_ERR == EAGAIN)
+		tst_res(TPASS, "tgkill() failed with EAGAIN as expected");
+	else
+		tst_res(TFAIL | TTERRNO,
+			"tgkill() should have failed with EAGAIN");
+
+	TST_CHECKPOINT_WAKE(0);
+
+	SAFE_PTHREAD_JOIN(thread, NULL);
+}
+
+static struct tst_test test = {
+	.needs_checkpoints = 1,
+	.test_all = run,
+};