1 files changed, 82 insertions, 0 deletions
diff --git a/include/linux/rcupdate_wait.h b/include/linux/rcupdate_wait.h
new file mode 100644
index 000000000000..4c92d4291cce
--- /dev/null
+++ b/include/linux/rcupdate_wait.h
@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_SCHED_RCUPDATE_WAIT_H
+#define _LINUX_SCHED_RCUPDATE_WAIT_H
+
+/*
+ * RCU synchronization types and methods:
+ */
+
+#include <linux/rcupdate.h>
+#include <linux/completion.h>
+#include <linux/sched.h>
+
+/*
+ * Structure allowing asynchronous waiting on RCU.
+ */
+struct rcu_synchronize {
+	struct rcu_head head;
+	struct completion completion;
+
+	/* This is for debugging. */
+	struct rcu_gp_oldstate oldstate;
+};
+void wakeme_after_rcu(struct rcu_head *head);
+
+void __wait_rcu_gp(bool checktiny, unsigned int state, int n, call_rcu_func_t *crcu_array,
+		   struct rcu_synchronize *rs_array);
+
+#define _wait_rcu_gp(checktiny, state, ...) \
+do {												\
+	call_rcu_func_t __crcu_array[] = { __VA_ARGS__ };					\
+	struct rcu_synchronize __rs_array[ARRAY_SIZE(__crcu_array)];				\
+	__wait_rcu_gp(checktiny, state, ARRAY_SIZE(__crcu_array), __crcu_array, __rs_array);	\
+} while (0)
+
+#define wait_rcu_gp(...) _wait_rcu_gp(false, TASK_UNINTERRUPTIBLE, __VA_ARGS__)
+#define wait_rcu_gp_state(state, ...) _wait_rcu_gp(false, state, __VA_ARGS__)
+
+/**
+ * synchronize_rcu_mult - Wait concurrently for multiple grace periods
+ * @...: List of call_rcu() functions for different grace periods to wait on
+ *
+ * This macro waits concurrently for multiple types of RCU grace periods.
+ * For example, synchronize_rcu_mult(call_rcu, call_rcu_tasks) would wait
+ * on concurrent RCU and RCU-tasks grace periods.  Waiting on a given SRCU
+ * domain requires you to write a wrapper function for that SRCU domain's
+ * call_srcu() function, with this wrapper supplying the pointer to the
+ * corresponding srcu_struct.
+ *
+ * Note that call_rcu_hurry() should be used instead of call_rcu()
+ * because in kernels built with CONFIG_RCU_LAZY=y the delay between the
+ * invocation of call_rcu() and that of the corresponding RCU callback
+ * can be multiple seconds.
+ *
+ * The first argument tells Tiny RCU's _wait_rcu_gp() not to
+ * bother waiting for RCU.  The reason for this is because anywhere
+ * synchronize_rcu_mult() can be called is automatically already a full
+ * grace period.
+ */
+#define synchronize_rcu_mult(...) \
+	_wait_rcu_gp(IS_ENABLED(CONFIG_TINY_RCU), TASK_UNINTERRUPTIBLE, __VA_ARGS__)
+
+static inline void cond_resched_rcu(void)
+{
+#if defined(CONFIG_DEBUG_ATOMIC_SLEEP) || !defined(CONFIG_PREEMPT_RCU)
+	rcu_read_unlock();
+	cond_resched();
+	rcu_read_lock();
+#endif
+}
+
+// Has the current task blocked within its current RCU read-side
+// critical section?
+static inline bool has_rcu_reader_blocked(void)
+{
+#ifdef CONFIG_PREEMPT_RCU
+	return !list_empty(&current->rcu_node_entry);
+#else
+	return false;
+#endif
+}
+
+#endif /* _LINUX_SCHED_RCUPDATE_WAIT_H */