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 unsigned long get_state_synchronize_rcu(void);
18 unsigned long start_poll_synchronize_rcu(void);
19 bool poll_state_synchronize_rcu(unsigned long oldstate);
20 
cond_synchronize_rcu(unsigned long oldstate)21 static inline void cond_synchronize_rcu(unsigned long oldstate)
22 {
23 	might_sleep();
24 }
25 
26 extern void rcu_barrier(void);
27 
synchronize_rcu_expedited(void)28 static inline void synchronize_rcu_expedited(void)
29 {
30 	synchronize_rcu();
31 }
32 
33 /*
34  * Add one more declaration of kvfree() here. It is
35  * not so straight forward to just include <linux/mm.h>
36  * where it is defined due to getting many compile
37  * errors caused by that include.
38  */
39 extern void kvfree(const void *addr);
40 
kvfree_call_rcu(struct rcu_head * head,rcu_callback_t func)41 static inline void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
42 {
43 	if (head) {
44 		call_rcu(head, func);
45 		return;
46 	}
47 
48 	// kvfree_rcu(one_arg) call.
49 	might_sleep();
50 	synchronize_rcu();
51 	kvfree((void *) func);
52 }
53 
54 void rcu_qs(void);
55 
rcu_softirq_qs(void)56 static inline void rcu_softirq_qs(void)
57 {
58 	rcu_qs();
59 }
60 
61 #define rcu_note_context_switch(preempt) \
62 	do { \
63 		rcu_qs(); \
64 		rcu_tasks_qs(current, (preempt)); \
65 	} while (0)
66 
rcu_needs_cpu(u64 basemono,u64 * nextevt)67 static inline int rcu_needs_cpu(u64 basemono, u64 *nextevt)
68 {
69 	*nextevt = KTIME_MAX;
70 	return 0;
71 }
72 
73 /*
74  * Take advantage of the fact that there is only one CPU, which
75  * allows us to ignore virtualization-based context switches.
76  */
rcu_virt_note_context_switch(int cpu)77 static inline void rcu_virt_note_context_switch(int cpu) { }
rcu_cpu_stall_reset(void)78 static inline void rcu_cpu_stall_reset(void) { }
rcu_jiffies_till_stall_check(void)79 static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; }
rcu_idle_enter(void)80 static inline void rcu_idle_enter(void) { }
rcu_idle_exit(void)81 static inline void rcu_idle_exit(void) { }
rcu_irq_enter(void)82 static inline void rcu_irq_enter(void) { }
rcu_irq_exit_irqson(void)83 static inline void rcu_irq_exit_irqson(void) { }
rcu_irq_enter_irqson(void)84 static inline void rcu_irq_enter_irqson(void) { }
rcu_irq_exit(void)85 static inline void rcu_irq_exit(void) { }
rcu_irq_exit_check_preempt(void)86 static inline void rcu_irq_exit_check_preempt(void) { }
87 #define rcu_is_idle_cpu(cpu) \
88 	(is_idle_task(current) && !in_nmi() && !in_irq() && !in_serving_softirq())
exit_rcu(void)89 static inline void exit_rcu(void) { }
rcu_preempt_need_deferred_qs(struct task_struct * t)90 static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t)
91 {
92 	return false;
93 }
rcu_preempt_deferred_qs(struct task_struct * t)94 static inline void rcu_preempt_deferred_qs(struct task_struct *t) { }
95 #ifdef CONFIG_SRCU
96 void rcu_scheduler_starting(void);
97 #else /* #ifndef CONFIG_SRCU */
rcu_scheduler_starting(void)98 static inline void rcu_scheduler_starting(void) { }
99 #endif /* #else #ifndef CONFIG_SRCU */
rcu_end_inkernel_boot(void)100 static inline void rcu_end_inkernel_boot(void) { }
rcu_inkernel_boot_has_ended(void)101 static inline bool rcu_inkernel_boot_has_ended(void) { return true; }
rcu_is_watching(void)102 static inline bool rcu_is_watching(void) { return true; }
rcu_momentary_dyntick_idle(void)103 static inline void rcu_momentary_dyntick_idle(void) { }
kfree_rcu_scheduler_running(void)104 static inline void kfree_rcu_scheduler_running(void) { }
rcu_gp_might_be_stalled(void)105 static inline bool rcu_gp_might_be_stalled(void) { return false; }
106 
107 /* Avoid RCU read-side critical sections leaking across. */
rcu_all_qs(void)108 static inline void rcu_all_qs(void) { barrier(); }
109 
110 /* RCUtree hotplug events */
111 #define rcutree_prepare_cpu      NULL
112 #define rcutree_online_cpu       NULL
113 #define rcutree_offline_cpu      NULL
114 #define rcutree_dead_cpu         NULL
115 #define rcutree_dying_cpu        NULL
rcu_cpu_starting(unsigned int cpu)116 static inline void rcu_cpu_starting(unsigned int cpu) { }
117 
118 #endif /* __LINUX_RCUTINY_H */
119