1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_SCHED_RCUPDATE_WAIT_H
3#define _LINUX_SCHED_RCUPDATE_WAIT_H
4
5/*
6 * RCU synchronization types and methods:
7 */
8
9#include <linux/rcupdate.h>
10#include <linux/completion.h>
11#include <linux/sched.h>
12
13/*
14 * Structure allowing asynchronous waiting on RCU.
15 */
16struct rcu_synchronize {
17	struct rcu_head head;
18	struct completion completion;
19};
20void wakeme_after_rcu(struct rcu_head *head);
21
22void __wait_rcu_gp(bool checktiny, int n, call_rcu_func_t *crcu_array,
23		   struct rcu_synchronize *rs_array);
24
25#define _wait_rcu_gp(checktiny, ...) \
26do {									\
27	call_rcu_func_t __crcu_array[] = { __VA_ARGS__ };		\
28	struct rcu_synchronize __rs_array[ARRAY_SIZE(__crcu_array)];	\
29	__wait_rcu_gp(checktiny, ARRAY_SIZE(__crcu_array),		\
30			__crcu_array, __rs_array);			\
31} while (0)
32
33#define wait_rcu_gp(...) _wait_rcu_gp(false, __VA_ARGS__)
34
35/**
36 * synchronize_rcu_mult - Wait concurrently for multiple grace periods
37 * @...: List of call_rcu() functions for different grace periods to wait on
38 *
39 * This macro waits concurrently for multiple types of RCU grace periods.
40 * For example, synchronize_rcu_mult(call_rcu, call_rcu_tasks) would wait
41 * on concurrent RCU and RCU-tasks grace periods.  Waiting on a given SRCU
42 * domain requires you to write a wrapper function for that SRCU domain's
43 * call_srcu() function, with this wrapper supplying the pointer to the
44 * corresponding srcu_struct.
45 *
46 * Note that call_rcu_hurry() should be used instead of call_rcu()
47 * because in kernels built with CONFIG_RCU_LAZY=y the delay between the
48 * invocation of call_rcu() and that of the corresponding RCU callback
49 * can be multiple seconds.
50 *
51 * The first argument tells Tiny RCU's _wait_rcu_gp() not to
52 * bother waiting for RCU.  The reason for this is because anywhere
53 * synchronize_rcu_mult() can be called is automatically already a full
54 * grace period.
55 */
56#define synchronize_rcu_mult(...) \
57	_wait_rcu_gp(IS_ENABLED(CONFIG_TINY_RCU), __VA_ARGS__)
58
59static inline void cond_resched_rcu(void)
60{
61#if defined(CONFIG_DEBUG_ATOMIC_SLEEP) || !defined(CONFIG_PREEMPT_RCU)
62	rcu_read_unlock();
63	cond_resched();
64	rcu_read_lock();
65#endif
66}
67
68#endif /* _LINUX_SCHED_RCUPDATE_WAIT_H */
69