rcutiny.h

  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
 17struct 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 */
 29static 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
 35unsigned long get_state_synchronize_rcu(void);
 36
 37static inline void get_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
 38{
 39	rgosp->rgos_norm = get_state_synchronize_rcu();
 40}
 41
 42unsigned long start_poll_synchronize_rcu(void);
 43
 44static inline void start_poll_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
 45{
 46	rgosp->rgos_norm = start_poll_synchronize_rcu();
 47}
 48
 49bool poll_state_synchronize_rcu(unsigned long oldstate);
 50
 51static inline bool poll_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
 52{
 53	return poll_state_synchronize_rcu(rgosp->rgos_norm);
 54}
 55
 56static inline void cond_synchronize_rcu(unsigned long oldstate)
 57{
 58	might_sleep();
 59}
 60
 61static inline void cond_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp)
 62{
 63	cond_synchronize_rcu(rgosp->rgos_norm);
 64}
 65
 66static inline unsigned long start_poll_synchronize_rcu_expedited(void)
 67{
 68	return start_poll_synchronize_rcu();
 69}
 70
 71static 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
 76static inline void cond_synchronize_rcu_expedited(unsigned long oldstate)
 77{
 78	cond_synchronize_rcu(oldstate);
 79}
 80
 81static inline void cond_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp)
 82{
 83	cond_synchronize_rcu_expedited(rgosp->rgos_norm);
 84}
 85
 86extern void rcu_barrier(void);
 87
 88static inline void synchronize_rcu_expedited(void)
 89{
 90	synchronize_rcu();
 91}
 92
 93void rcu_qs(void);
 94
 95static 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
106static inline int rcu_needs_cpu(void)
107{
108	return 0;
109}
110
111static 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 */
117static inline void rcu_virt_note_context_switch(void) { }
118static inline void rcu_cpu_stall_reset(void) { }
119static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; }
120static inline void rcu_irq_exit_check_preempt(void) { }
121static inline void exit_rcu(void) { }
122static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t)
123{
124	return false;
125}
126static inline void rcu_preempt_deferred_qs(struct task_struct *t) { }
127void rcu_scheduler_starting(void);
128static inline void rcu_end_inkernel_boot(void) { }
129static inline bool rcu_inkernel_boot_has_ended(void) { return true; }
130static inline bool rcu_is_watching(void) { return true; }
131static inline void rcu_momentary_eqs(void) { }
132
133/* Avoid RCU read-side critical sections leaking across. */
134static 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
142static inline void rcutree_report_cpu_starting(unsigned int cpu) { }
143
144#endif /* __LINUX_RCUTINY_H */