rcupdate_wait.h

 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
20	/* This is for debugging. */
21	struct rcu_gp_oldstate oldstate;
22};
23void wakeme_after_rcu(struct rcu_head *head);
24
25void __wait_rcu_gp(bool checktiny, unsigned int state, int n, call_rcu_func_t *crcu_array,
26		   struct rcu_synchronize *rs_array);
27
28#define _wait_rcu_gp(checktiny, state, ...) \
29do {												\
30	call_rcu_func_t __crcu_array[] = { __VA_ARGS__ };					\
31	struct rcu_synchronize __rs_array[ARRAY_SIZE(__crcu_array)];				\
32	__wait_rcu_gp(checktiny, state, ARRAY_SIZE(__crcu_array), __crcu_array, __rs_array);	\
33} while (0)
34
35#define wait_rcu_gp(...) _wait_rcu_gp(false, TASK_UNINTERRUPTIBLE, __VA_ARGS__)
36#define wait_rcu_gp_state(state, ...) _wait_rcu_gp(false, state, __VA_ARGS__)
37
38/**
39 * synchronize_rcu_mult - Wait concurrently for multiple grace periods
40 * @...: List of call_rcu() functions for different grace periods to wait on
41 *
42 * This macro waits concurrently for multiple types of RCU grace periods.
43 * For example, synchronize_rcu_mult(call_rcu, call_rcu_tasks) would wait
44 * on concurrent RCU and RCU-tasks grace periods.  Waiting on a given SRCU
45 * domain requires you to write a wrapper function for that SRCU domain's
46 * call_srcu() function, with this wrapper supplying the pointer to the
47 * corresponding srcu_struct.
48 *
49 * Note that call_rcu_hurry() should be used instead of call_rcu()
50 * because in kernels built with CONFIG_RCU_LAZY=y the delay between the
51 * invocation of call_rcu() and that of the corresponding RCU callback
52 * can be multiple seconds.
53 *
54 * The first argument tells Tiny RCU's _wait_rcu_gp() not to
55 * bother waiting for RCU.  The reason for this is because anywhere
56 * synchronize_rcu_mult() can be called is automatically already a full
57 * grace period.
58 */
59#define synchronize_rcu_mult(...) \
60	_wait_rcu_gp(IS_ENABLED(CONFIG_TINY_RCU), TASK_UNINTERRUPTIBLE, __VA_ARGS__)
61
62static inline void cond_resched_rcu(void)
63{
64#if defined(CONFIG_DEBUG_ATOMIC_SLEEP) || !defined(CONFIG_PREEMPT_RCU)
65	rcu_read_unlock();
66	cond_resched();
67	rcu_read_lock();
68#endif
69}
70
71// Has the current task blocked within its current RCU read-side
72// critical section?
73static inline bool has_rcu_reader_blocked(void)
74{
75#ifdef CONFIG_PREEMPT_RCU
76	return !list_empty(&current->rcu_node_entry);
77#else
78	return false;
79#endif
80}
81
82#endif /* _LINUX_SCHED_RCUPDATE_WAIT_H */