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1/* SPDX-License-Identifier: GPL-2.0+ */
2/*
3 * Read-Copy Update mechanism for mutual exclusion, the Bloatwatch edition.
4 *
5 * Copyright IBM Corporation, 2008
6 *
7 * Author: Paul E. McKenney <paulmck@linux.ibm.com>
8 *
9 * For detailed explanation of Read-Copy Update mechanism see -
10 * Documentation/RCU
11 */
12#ifndef __LINUX_TINY_H
13#define __LINUX_TINY_H
14
15#include <asm/param.h> /* for HZ */
16
17struct rcu_gp_oldstate {
18 unsigned long rgos_norm;
19};
20
21// Maximum number of rcu_gp_oldstate values corresponding to
22// not-yet-completed RCU grace periods.
23#define NUM_ACTIVE_RCU_POLL_FULL_OLDSTATE 2
24
25/*
26 * Are the two oldstate values the same? See the Tree RCU version for
27 * docbook header.
28 */
29static inline bool same_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp1,
30 struct rcu_gp_oldstate *rgosp2)
31{
32 return rgosp1->rgos_norm == rgosp2->rgos_norm;
33}
34
35unsigned long get_state_synchronize_rcu(void);
36
37static inline void get_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
38{
39 rgosp->rgos_norm = get_state_synchronize_rcu();
40}
41
42unsigned long start_poll_synchronize_rcu(void);
43
44static inline void start_poll_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
45{
46 rgosp->rgos_norm = start_poll_synchronize_rcu();
47}
48
49bool poll_state_synchronize_rcu(unsigned long oldstate);
50
51static inline bool poll_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
52{
53 return poll_state_synchronize_rcu(rgosp->rgos_norm);
54}
55
56static inline void cond_synchronize_rcu(unsigned long oldstate)
57{
58 might_sleep();
59}
60
61static inline void cond_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
62{
63 cond_synchronize_rcu(rgosp->rgos_norm);
64}
65
66static inline unsigned long start_poll_synchronize_rcu_expedited(void)
67{
68 return start_poll_synchronize_rcu();
69}
70
71static inline void start_poll_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp)
72{
73 rgosp->rgos_norm = start_poll_synchronize_rcu_expedited();
74}
75
76static inline void cond_synchronize_rcu_expedited(unsigned long oldstate)
77{
78 cond_synchronize_rcu(oldstate);
79}
80
81static inline void cond_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp)
82{
83 cond_synchronize_rcu_expedited(rgosp->rgos_norm);
84}
85
86extern void rcu_barrier(void);
87
88static inline void synchronize_rcu_expedited(void)
89{
90 synchronize_rcu();
91}
92
93void rcu_qs(void);
94
95static inline void rcu_softirq_qs(void)
96{
97 rcu_qs();
98}
99
100#define rcu_note_context_switch(preempt) \
101 do { \
102 rcu_qs(); \
103 rcu_tasks_qs(current, (preempt)); \
104 } while (0)
105
106static inline int rcu_needs_cpu(void)
107{
108 return 0;
109}
110
111static inline void rcu_request_urgent_qs_task(struct task_struct *t) { }
112
113/*
114 * Take advantage of the fact that there is only one CPU, which
115 * allows us to ignore virtualization-based context switches.
116 */
117static inline void rcu_virt_note_context_switch(void) { }
118static inline void rcu_cpu_stall_reset(void) { }
119static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; }
120static inline void rcu_irq_exit_check_preempt(void) { }
121static inline void exit_rcu(void) { }
122static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t)
123{
124 return false;
125}
126static inline void rcu_preempt_deferred_qs(struct task_struct *t) { }
127void rcu_scheduler_starting(void);
128static inline void rcu_end_inkernel_boot(void) { }
129static inline bool rcu_inkernel_boot_has_ended(void) { return true; }
130static inline bool rcu_is_watching(void) { return true; }
131static inline void rcu_momentary_eqs(void) { }
132
133/* Avoid RCU read-side critical sections leaking across. */
134static inline void rcu_all_qs(void) { barrier(); }
135
136/* RCUtree hotplug events */
137#define rcutree_prepare_cpu NULL
138#define rcutree_online_cpu NULL
139#define rcutree_offline_cpu NULL
140#define rcutree_dead_cpu NULL
141#define rcutree_dying_cpu NULL
142static inline void rcutree_report_cpu_starting(unsigned int cpu) { }
143
144#endif /* __LINUX_RCUTINY_H */