xref: /linux/include/linux/rcupdate_wait.h (revision 621cde16e49b3ecf7d59a8106a20aaebfb4a59a9)
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  */
16 struct rcu_synchronize {
17 	struct rcu_head head;
18 	struct completion completion;
19 };
20 void wakeme_after_rcu(struct rcu_head *head);
21 
22 void __wait_rcu_gp(bool checktiny, unsigned int state, int n, call_rcu_func_t *crcu_array,
23 		   struct rcu_synchronize *rs_array);
24 
25 #define _wait_rcu_gp(checktiny, state, ...) \
26 do {												\
27 	call_rcu_func_t __crcu_array[] = { __VA_ARGS__ };					\
28 	struct rcu_synchronize __rs_array[ARRAY_SIZE(__crcu_array)];				\
29 	__wait_rcu_gp(checktiny, state, ARRAY_SIZE(__crcu_array), __crcu_array, __rs_array);	\
30 } while (0)
31 
32 #define wait_rcu_gp(...) _wait_rcu_gp(false, TASK_UNINTERRUPTIBLE, __VA_ARGS__)
33 #define wait_rcu_gp_state(state, ...) _wait_rcu_gp(false, state, __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), TASK_UNINTERRUPTIBLE, __VA_ARGS__)
58 
cond_resched_rcu(void)59 static 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