LXR linux/include/linux/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
  17/* Never flag non-existent other CPUs! */
  18static inline bool rcu_eqs_special_set(int cpu) { return false; }
  19
  20static inline unsigned long get_state_synchronize_rcu(void)
  21{
  22        return 0;
  23}
  24
  25static inline void cond_synchronize_rcu(unsigned long oldstate)
  26{
  27        might_sleep();
  28}
  29
  30extern void rcu_barrier(void);
  31
  32static inline void synchronize_rcu_expedited(void)
  33{
  34        synchronize_rcu();
  35}
  36
  37static inline void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func)
  38{
  39        call_rcu(head, func);
  40}
  41
  42void rcu_qs(void);
  43
  44static inline void rcu_softirq_qs(void)
  45{
  46        rcu_qs();
  47}
  48
  49#define rcu_note_context_switch(preempt) \
  50        do { \
  51                rcu_qs(); \
  52                rcu_tasks_qs(current); \
  53        } while (0)
  54
  55static inline int rcu_needs_cpu(u64 basemono, u64 *nextevt)
  56{
  57        *nextevt = KTIME_MAX;
  58        return 0;
  59}
  60
  61/*
  62 * Take advantage of the fact that there is only one CPU, which
  63 * allows us to ignore virtualization-based context switches.
  64 */
  65static inline void rcu_virt_note_context_switch(int cpu) { }
  66static inline void rcu_cpu_stall_reset(void) { }
  67static inline int rcu_jiffies_till_stall_check(void) { return 21 * HZ; }
  68static inline void rcu_idle_enter(void) { }
  69static inline void rcu_idle_exit(void) { }
  70static inline void rcu_irq_enter(void) { }
  71static inline void rcu_irq_exit_irqson(void) { }
  72static inline void rcu_irq_enter_irqson(void) { }
  73static inline void rcu_irq_exit(void) { }
  74static inline void exit_rcu(void) { }
  75static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t)
  76{
  77        return false;
  78}
  79static inline void rcu_preempt_deferred_qs(struct task_struct *t) { }
  80#ifdef CONFIG_SRCU
  81void rcu_scheduler_starting(void);
  82#else /* #ifndef CONFIG_SRCU */
  83static inline void rcu_scheduler_starting(void) { }
  84#endif /* #else #ifndef CONFIG_SRCU */
  85static inline void rcu_end_inkernel_boot(void) { }
  86static inline bool rcu_inkernel_boot_has_ended(void) { return true; }
  87static inline bool rcu_is_watching(void) { return true; }
  88static inline void rcu_momentary_dyntick_idle(void) { }
  89static inline void kfree_rcu_scheduler_running(void) { }
  90
  91/* Avoid RCU read-side critical sections leaking across. */
  92static inline void rcu_all_qs(void) { barrier(); }
  93
  94/* RCUtree hotplug events */
  95#define rcutree_prepare_cpu      NULL
  96#define rcutree_online_cpu       NULL
  97#define rcutree_offline_cpu      NULL
  98#define rcutree_dead_cpu         NULL
  99#define rcutree_dying_cpu        NULL
 100static inline void rcu_cpu_starting(unsigned int cpu) { }
 101
 102#endif /* __LINUX_RCUTINY_H */
 103