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
17 struct 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 */
29 static 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
35 unsigned long get_state_synchronize_rcu(void);
36
37 static inline void get_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
38 {
39 rgosp->rgos_norm = get_state_synchronize_rcu();
40 }
41
42 unsigned long start_poll_synchronize_rcu(void);
43
44 static inline void start_poll_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
45 {
46 rgosp->rgos_norm = start_poll_synchronize_rcu();
47 }
48
49 bool poll_state_synchronize_rcu(unsigned long oldstate);
50
51 static inline bool poll_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
52 {
53 return poll_state_synchronize_rcu(rgosp->rgos_norm);
54 }
55
56 static inline void cond_synchronize_rcu(unsigned long oldstate)
57 {
58 might_sleep();
59 }
60
61 static inline void cond_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
62 {
63 cond_synchronize_rcu(rgosp->rgos_norm);
64 }
65
66 static inline unsigned long start_poll_synchronize_rcu_expedited(void)
67 {
68 return start_poll_synchronize_rcu();
69 }
70
71 static 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
76 static inline void cond_synchronize_rcu_expedited(unsigned long oldstate)
77 {
78 cond_synchronize_rcu(oldstate);
79 }
80
81 static inline void cond_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp)
82 {
83 cond_synchronize_rcu_expedited(rgosp->rgos_norm);
84 }
85
86 extern void rcu_barrier(void);
87
88 static 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 */
99 extern void kvfree(const void *addr);
100
101 static 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
114 #ifdef CONFIG_KASAN_GENERIC
115 void kvfree_call_rcu(struct rcu_head *head, void *ptr);
116 #else
117 static inline void kvfree_call_rcu(struct rcu_head *head, void *ptr)
118 {
119 __kvfree_call_rcu(head, ptr);
120 }
121 #endif
122
123 void rcu_qs(void);
124
125 static inline void rcu_softirq_qs(void)
126 {
127 rcu_qs();
128 }
129
130 #define rcu_note_context_switch(preempt) \
131 do { \
132 rcu_qs(); \
133 rcu_tasks_qs(current, (preempt)); \
134 } while (0)
135
136 static inline int rcu_needs_cpu(void)
137 {
138 return 0;
139 }
140
141 static inline void rcu_request_urgent_qs_task(struct task_struct *t) { }
142
143 /*
144 * Take advantage of the fact that there is only one CPU, which
145 * allows us to ignore virtualization-based context switches.
146 */
147 static inline void rcu_virt_note_context_switch(void) { }
148 static inline void rcu_cpu_stall_reset(void) { }
149 static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; }
150 static inline void rcu_irq_exit_check_preempt(void) { }
151 static inline void exit_rcu(void) { }
152 static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t)
153 {
154 return false;
155 }
156 static inline void rcu_preempt_deferred_qs(struct task_struct *t) { }
157 void rcu_scheduler_starting(void);
158 static inline void rcu_end_inkernel_boot(void) { }
159 static inline bool rcu_inkernel_boot_has_ended(void) { return true; }
160 static inline bool rcu_is_watching(void) { return true; }
161 static inline void rcu_momentary_dyntick_idle(void) { }
162 static inline void kfree_rcu_scheduler_running(void) { }
163 static inline bool rcu_gp_might_be_stalled(void) { return false; }
164
165 /* Avoid RCU read-side critical sections leaking across. */
166 static inline void rcu_all_qs(void) { barrier(); }
167
168 /* RCUtree hotplug events */
169 #define rcutree_prepare_cpu NULL
170 #define rcutree_online_cpu NULL
171 #define rcutree_offline_cpu NULL
172 #define rcutree_dead_cpu NULL
173 #define rcutree_dying_cpu NULL
174 static inline void rcutree_report_cpu_starting(unsigned int cpu) { }
175
176 #endif /* __LINUX_RCUTINY_H */
177
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