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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
93/*
94 * Add one more declaration of kvfree() here. It is
95 * not so straight forward to just include <linux/mm.h>
96 * where it is defined due to getting many compile
97 * errors caused by that include.
98 */
99extern void kvfree(const void *addr);
100
101static inline void __kvfree_call_rcu(struct rcu_head *head, void *ptr)
102{
103 if (head) {
104 call_rcu(head, (rcu_callback_t) ((void *) head - ptr));
105 return;
106 }
107
108 // kvfree_rcu(one_arg) call.
109 might_sleep();
110 synchronize_rcu();
111 kvfree(ptr);
112}
113
114static inline void kvfree_rcu_barrier(void)
115{
116 rcu_barrier();
117}
118
119#ifdef CONFIG_KASAN_GENERIC
120void kvfree_call_rcu(struct rcu_head *head, void *ptr);
121#else
122static inline void kvfree_call_rcu(struct rcu_head *head, void *ptr)
123{
124 __kvfree_call_rcu(head, ptr);
125}
126#endif
127
128void rcu_qs(void);
129
130static inline void rcu_softirq_qs(void)
131{
132 rcu_qs();
133}
134
135#define rcu_note_context_switch(preempt) \
136 do { \
137 rcu_qs(); \
138 rcu_tasks_qs(current, (preempt)); \
139 } while (0)
140
141static inline int rcu_needs_cpu(void)
142{
143 return 0;
144}
145
146static inline void rcu_request_urgent_qs_task(struct task_struct *t) { }
147
148/*
149 * Take advantage of the fact that there is only one CPU, which
150 * allows us to ignore virtualization-based context switches.
151 */
152static inline void rcu_virt_note_context_switch(void) { }
153static inline void rcu_cpu_stall_reset(void) { }
154static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; }
155static inline void rcu_irq_exit_check_preempt(void) { }
156static inline void exit_rcu(void) { }
157static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t)
158{
159 return false;
160}
161static inline void rcu_preempt_deferred_qs(struct task_struct *t) { }
162void rcu_scheduler_starting(void);
163static inline void rcu_end_inkernel_boot(void) { }
164static inline bool rcu_inkernel_boot_has_ended(void) { return true; }
165static inline bool rcu_is_watching(void) { return true; }
166static inline void rcu_momentary_eqs(void) { }
167static inline void kfree_rcu_scheduler_running(void) { }
168
169/* Avoid RCU read-side critical sections leaking across. */
170static inline void rcu_all_qs(void) { barrier(); }
171
172/* RCUtree hotplug events */
173#define rcutree_prepare_cpu NULL
174#define rcutree_online_cpu NULL
175#define rcutree_offline_cpu NULL
176#define rcutree_dead_cpu NULL
177#define rcutree_dying_cpu NULL
178static inline void rcutree_report_cpu_starting(unsigned int cpu) { }
179
180#endif /* __LINUX_RCUTINY_H */