v4.19.13 snapshot.
diff --git a/include/linux/signalfd.h b/include/linux/signalfd.h
new file mode 100644
index 0000000..9a47c38
--- /dev/null
+++ b/include/linux/signalfd.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * include/linux/signalfd.h
+ *
+ * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org>
+ *
+ */
+#ifndef _LINUX_SIGNALFD_H
+#define _LINUX_SIGNALFD_H
+
+#include <uapi/linux/signalfd.h>
+#include <linux/sched/signal.h>
+
+#ifdef CONFIG_SIGNALFD
+
+/*
+ * Deliver the signal to listening signalfd.
+ */
+static inline void signalfd_notify(struct task_struct *tsk, int sig)
+{
+ if (unlikely(waitqueue_active(&tsk->sighand->signalfd_wqh)))
+ wake_up(&tsk->sighand->signalfd_wqh);
+}
+
+extern void signalfd_cleanup(struct sighand_struct *sighand);
+
+#else /* CONFIG_SIGNALFD */
+
+static inline void signalfd_notify(struct task_struct *tsk, int sig) { }
+
+static inline void signalfd_cleanup(struct sighand_struct *sighand) { }
+
+#endif /* CONFIG_SIGNALFD */
+
+#endif /* _LINUX_SIGNALFD_H */