1 /* SPDX-License-Identifier: GPL-2.0+ */
2 /*
3 * Read-Copy Update mechanism for mutual exclusion (tree-based version)
4 *
5 * Copyright IBM Corporation, 2008
6 *
7 * Author: Dipankar Sarma <dipankar@in.ibm.com>
8 * Paul E. McKenney <paulmck@linux.ibm.com> Hierarchical algorithm
9 *
10 * Based on the original work by Paul McKenney <paulmck@linux.ibm.com>
11 * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen.
12 *
13 * For detailed explanation of Read-Copy Update mechanism see -
14 * Documentation/RCU
15 */
16
17 #ifndef __LINUX_RCUTREE_H
18 #define __LINUX_RCUTREE_H
19
20 void rcu_softirq_qs(void);
21 void rcu_note_context_switch(bool preempt);
22 int rcu_needs_cpu(void);
23 void rcu_cpu_stall_reset(void);
24 void rcu_request_urgent_qs_task(struct task_struct *t);
25
26 /*
27 * Note a virtualization-based context switch. This is simply a
28 * wrapper around rcu_note_context_switch(), which allows TINY_RCU
29 * to save a few bytes. The caller must have disabled interrupts.
30 */
rcu_virt_note_context_switch(void)31 static inline void rcu_virt_note_context_switch(void)
32 {
33 rcu_note_context_switch(false);
34 }
35
36 void synchronize_rcu_expedited(void);
37
38 void rcu_barrier(void);
39 void rcu_momentary_eqs(void);
40
41 // Maximum number of rcu_gp_seq values corresponding to
42 // not-yet-completed RCU grace periods.
43 #define NUM_ACTIVE_RCU_POLL_FULL_OLDSTATE 4
44
45 /**
46 * same_state_synchronize_rcu_full - Are two old-state values identical?
47 * @rgosp1: First old-state value.
48 * @rgosp2: Second old-state value.
49 *
50 * The two old-state values must have been obtained from either
51 * get_state_synchronize_rcu_full(), start_poll_synchronize_rcu_full(),
52 * or get_completed_synchronize_rcu_full(). Returns @true if the two
53 * values are identical and @false otherwise. This allows structures
54 * whose lifetimes are tracked by old-state values to push these values
55 * to a list header, allowing those structures to be slightly smaller.
56 *
57 * Note that equality is judged on a bitwise basis, so that an
58 * @rcu_gp_seq structure with an already-completed state in one field
59 * will compare not-equal to a structure with an already-completed state
60 * in the other field. After all, the @rcu_gp_seq structure is opaque
61 * so how did such a situation come to pass in the first place?
62 */
same_state_synchronize_rcu_full(struct rcu_gp_seq * rgosp1,struct rcu_gp_seq * rgosp2)63 static inline bool same_state_synchronize_rcu_full(struct rcu_gp_seq *rgosp1,
64 struct rcu_gp_seq *rgosp2)
65 {
66 return rgosp1->norm == rgosp2->norm && rgosp1->exp == rgosp2->exp;
67 }
68
69 unsigned long start_poll_synchronize_rcu_expedited(void);
70 void start_poll_synchronize_rcu_expedited_full(struct rcu_gp_seq *gsp);
71 void cond_synchronize_rcu_expedited(unsigned long oldstate);
72 void cond_synchronize_rcu_expedited_full(struct rcu_gp_seq *gsp);
73 unsigned long get_state_synchronize_rcu(void);
74 void get_state_synchronize_rcu_full(struct rcu_gp_seq *gsp);
75 unsigned long start_poll_synchronize_rcu(void);
76 void start_poll_synchronize_rcu_full(struct rcu_gp_seq *gsp);
77 bool poll_state_synchronize_rcu(unsigned long oldstate);
78 bool poll_state_synchronize_rcu_full(struct rcu_gp_seq *gsp);
79 void cond_synchronize_rcu(unsigned long oldstate);
80 void cond_synchronize_rcu_full(struct rcu_gp_seq *gsp);
81
82 #ifdef CONFIG_PROVE_RCU
83 void rcu_irq_exit_check_preempt(void);
84 #else
rcu_irq_exit_check_preempt(void)85 static inline void rcu_irq_exit_check_preempt(void) { }
86 #endif
87
88 struct task_struct;
89 void rcu_preempt_deferred_qs(struct task_struct *t);
90
91 void exit_rcu(void);
92
93 void rcu_scheduler_starting(void);
94 extern int rcu_scheduler_active;
95 void rcu_end_inkernel_boot(void);
96 bool rcu_inkernel_boot_has_ended(void);
97 bool rcu_is_watching(void);
98 #ifndef CONFIG_PREEMPT_RCU
99 void rcu_all_qs(void);
100 #endif
101
102 /* RCUtree hotplug events */
103 int rcutree_prepare_cpu(unsigned int cpu);
104 int rcutree_online_cpu(unsigned int cpu);
105 void rcutree_report_cpu_starting(unsigned int cpu);
106
107 #ifdef CONFIG_HOTPLUG_CPU
108 int rcutree_dead_cpu(unsigned int cpu);
109 int rcutree_dying_cpu(unsigned int cpu);
110 int rcutree_offline_cpu(unsigned int cpu);
111 #else
112 #define rcutree_dead_cpu NULL
113 #define rcutree_dying_cpu NULL
114 #define rcutree_offline_cpu NULL
115 #endif
116
117 void rcutree_migrate_callbacks(int cpu);
118
119 /* Called from hotplug and also arm64 early secondary boot failure */
120 void rcutree_report_cpu_dead(void);
121
122 #endif /* __LINUX_RCUTREE_H */
123