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
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
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