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 /* This is for debugging. */
21 struct rcu_gp_oldstate oldstate;
22 };
23 void wakeme_after_rcu(struct rcu_head *head);
24
25 void __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, ...) \
29 do { \
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
cond_resched_rcu(void)62 static 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?
has_rcu_reader_blocked(void)73 static inline bool has_rcu_reader_blocked(void)
74 {
75 #ifdef CONFIG_PREEMPT_RCU
76 return !list_empty(¤t->rcu_node_entry);
77 #else
78 return false;
79 #endif
80 }
81
82 #endif /* _LINUX_SCHED_RCUPDATE_WAIT_H */
83