v4.19.13 snapshot.
diff --git a/include/linux/irq_work.h b/include/linux/irq_work.h
new file mode 100644
index 0000000..b11fcdf
--- /dev/null
+++ b/include/linux/irq_work.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_IRQ_WORK_H
+#define _LINUX_IRQ_WORK_H
+
+#include <linux/llist.h>
+
+/*
+ * An entry can be in one of four states:
+ *
+ * free NULL, 0 -> {claimed} : free to be used
+ * claimed NULL, 3 -> {pending} : claimed to be enqueued
+ * pending next, 3 -> {busy} : queued, pending callback
+ * busy NULL, 2 -> {free, claimed} : callback in progress, can be claimed
+ */
+
+#define IRQ_WORK_PENDING BIT(0)
+#define IRQ_WORK_BUSY BIT(1)
+
+/* Doesn't want IPI, wait for tick: */
+#define IRQ_WORK_LAZY BIT(2)
+
+#define IRQ_WORK_CLAIMED (IRQ_WORK_PENDING | IRQ_WORK_BUSY)
+
+struct irq_work {
+ unsigned long flags;
+ struct llist_node llnode;
+ void (*func)(struct irq_work *);
+};
+
+static inline
+void init_irq_work(struct irq_work *work, void (*func)(struct irq_work *))
+{
+ work->flags = 0;
+ work->func = func;
+}
+
+#define DEFINE_IRQ_WORK(name, _f) struct irq_work name = { .func = (_f), }
+
+bool irq_work_queue(struct irq_work *work);
+bool irq_work_queue_on(struct irq_work *work, int cpu);
+
+void irq_work_tick(void);
+void irq_work_sync(struct irq_work *work);
+
+#ifdef CONFIG_IRQ_WORK
+#include <asm/irq_work.h>
+
+void irq_work_run(void);
+bool irq_work_needs_cpu(void);
+#else
+static inline bool irq_work_needs_cpu(void) { return false; }
+static inline void irq_work_run(void) { }
+#endif
+
+#endif /* _LINUX_IRQ_WORK_H */