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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
17unsigned long get_state_synchronize_rcu(void);
18unsigned long start_poll_synchronize_rcu(void);
19bool poll_state_synchronize_rcu(unsigned long oldstate);
20
21static inline void cond_synchronize_rcu(unsigned long oldstate)
22{
23 might_sleep();
24}
25
26extern void rcu_barrier(void);
27
28static 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 */
39extern void kvfree(const void *addr);
40
41static 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
54void rcu_qs(void);
55
56static 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
67static inline int rcu_needs_cpu(void)
68{
69 return 0;
70}
71
72/*
73 * Take advantage of the fact that there is only one CPU, which
74 * allows us to ignore virtualization-based context switches.
75 */
76static inline void rcu_virt_note_context_switch(int cpu) { }
77static inline void rcu_cpu_stall_reset(void) { }
78static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; }
79static inline void rcu_idle_enter(void) { }
80static inline void rcu_idle_exit(void) { }
81static inline void rcu_irq_enter(void) { }
82static inline void rcu_irq_exit_irqson(void) { }
83static inline void rcu_irq_enter_irqson(void) { }
84static inline void rcu_irq_exit(void) { }
85static inline void rcu_irq_exit_check_preempt(void) { }
86#define rcu_is_idle_cpu(cpu) \
87 (is_idle_task(current) && !in_nmi() && !in_hardirq() && !in_serving_softirq())
88static inline void exit_rcu(void) { }
89static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t)
90{
91 return false;
92}
93static inline void rcu_preempt_deferred_qs(struct task_struct *t) { }
94#ifdef CONFIG_SRCU
95void rcu_scheduler_starting(void);
96#else /* #ifndef CONFIG_SRCU */
97static inline void rcu_scheduler_starting(void) { }
98#endif /* #else #ifndef CONFIG_SRCU */
99static inline void rcu_end_inkernel_boot(void) { }
100static inline bool rcu_inkernel_boot_has_ended(void) { return true; }
101static inline bool rcu_is_watching(void) { return true; }
102static inline void rcu_momentary_dyntick_idle(void) { }
103static inline void kfree_rcu_scheduler_running(void) { }
104static inline bool rcu_gp_might_be_stalled(void) { return false; }
105
106/* Avoid RCU read-side critical sections leaking across. */
107static inline void rcu_all_qs(void) { barrier(); }
108
109/* RCUtree hotplug events */
110#define rcutree_prepare_cpu NULL
111#define rcutree_online_cpu NULL
112#define rcutree_offline_cpu NULL
113#define rcutree_dead_cpu NULL
114#define rcutree_dying_cpu NULL
115static inline void rcu_cpu_starting(unsigned int cpu) { }
116
117#endif /* __LINUX_RCUTINY_H */