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  */
same_state_synchronize_rcu_full(struct rcu_gp_oldstate * rgosp1,struct rcu_gp_oldstate * rgosp2)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 
get_state_synchronize_rcu_full(struct rcu_gp_oldstate * rgosp)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 
start_poll_synchronize_rcu_full(struct rcu_gp_oldstate * rgosp)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 
poll_state_synchronize_rcu_full(struct rcu_gp_oldstate * rgosp)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 
cond_synchronize_rcu(unsigned long oldstate)56 static inline void cond_synchronize_rcu(unsigned long oldstate)
57 {
58 	might_sleep();
59 }
60 
cond_synchronize_rcu_full(struct rcu_gp_oldstate * rgosp)61 static inline void cond_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
62 {
63 	cond_synchronize_rcu(rgosp->rgos_norm);
64 }
65 
start_poll_synchronize_rcu_expedited(void)66 static inline unsigned long start_poll_synchronize_rcu_expedited(void)
67 {
68 	return start_poll_synchronize_rcu();
69 }
70 
start_poll_synchronize_rcu_expedited_full(struct rcu_gp_oldstate * rgosp)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 
cond_synchronize_rcu_expedited(unsigned long oldstate)76 static inline void cond_synchronize_rcu_expedited(unsigned long oldstate)
77 {
78 	cond_synchronize_rcu(oldstate);
79 }
80 
cond_synchronize_rcu_expedited_full(struct rcu_gp_oldstate * rgosp)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 
synchronize_rcu_expedited(void)88 static inline void synchronize_rcu_expedited(void)
89 {
90 	synchronize_rcu();
91 }
92 
93 void rcu_qs(void);
94 
rcu_softirq_qs(void)95 static 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 
rcu_needs_cpu(void)106 static inline int rcu_needs_cpu(void)
107 {
108 	return 0;
109 }
110 
rcu_request_urgent_qs_task(struct task_struct * t)111 static 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  */
rcu_virt_note_context_switch(void)117 static inline void rcu_virt_note_context_switch(void) { }
rcu_cpu_stall_reset(void)118 static inline void rcu_cpu_stall_reset(void) { }
rcu_jiffies_till_stall_check(void)119 static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; }
rcu_irq_exit_check_preempt(void)120 static inline void rcu_irq_exit_check_preempt(void) { }
exit_rcu(void)121 static inline void exit_rcu(void) { }
rcu_preempt_need_deferred_qs(struct task_struct * t)122 static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t)
123 {
124 	return false;
125 }
rcu_preempt_deferred_qs(struct task_struct * t)126 static inline void rcu_preempt_deferred_qs(struct task_struct *t) { }
127 void rcu_scheduler_starting(void);
rcu_end_inkernel_boot(void)128 static inline void rcu_end_inkernel_boot(void) { }
rcu_inkernel_boot_has_ended(void)129 static inline bool rcu_inkernel_boot_has_ended(void) { return true; }
rcu_is_watching(void)130 static inline bool rcu_is_watching(void) { return true; }
rcu_momentary_eqs(void)131 static inline void rcu_momentary_eqs(void) { }
132 
133 /* Avoid RCU read-side critical sections leaking across. */
rcu_all_qs(void)134 static 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
rcutree_report_cpu_starting(unsigned int cpu)142 static inline void rcutree_report_cpu_starting(unsigned int cpu) { }
143 
144 #endif /* __LINUX_RCUTINY_H */
145