rcutree.h

  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
 20void rcu_softirq_qs(void);
 21void rcu_note_context_switch(bool preempt);
 22int rcu_needs_cpu(void);
 23void rcu_cpu_stall_reset(void);
 24void 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 */
 31static inline void rcu_virt_note_context_switch(void)
 32{
 33	rcu_note_context_switch(false);
 34}
 35
 36void synchronize_rcu_expedited(void);
 37
 38void rcu_barrier(void);
 39void rcu_momentary_eqs(void);
 40
 41struct rcu_gp_oldstate {
 42	unsigned long rgos_norm;
 43	unsigned long rgos_exp;
 44};
 45
 46// Maximum number of rcu_gp_oldstate values corresponding to
 47// not-yet-completed RCU grace periods.
 48#define NUM_ACTIVE_RCU_POLL_FULL_OLDSTATE 4
 49
 50/**
 51 * same_state_synchronize_rcu_full - Are two old-state values identical?
 52 * @rgosp1: First old-state value.
 53 * @rgosp2: Second old-state value.
 54 *
 55 * The two old-state values must have been obtained from either
 56 * get_state_synchronize_rcu_full(), start_poll_synchronize_rcu_full(),
 57 * or get_completed_synchronize_rcu_full().  Returns @true if the two
 58 * values are identical and @false otherwise.  This allows structures
 59 * whose lifetimes are tracked by old-state values to push these values
 60 * to a list header, allowing those structures to be slightly smaller.
 61 *
 62 * Note that equality is judged on a bitwise basis, so that an
 63 * @rcu_gp_oldstate structure with an already-completed state in one field
 64 * will compare not-equal to a structure with an already-completed state
 65 * in the other field.  After all, the @rcu_gp_oldstate structure is opaque
 66 * so how did such a situation come to pass in the first place?
 67 */
 68static inline bool same_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp1,
 69						   struct rcu_gp_oldstate *rgosp2)
 70{
 71	return rgosp1->rgos_norm == rgosp2->rgos_norm && rgosp1->rgos_exp == rgosp2->rgos_exp;
 72}
 73
 74unsigned long start_poll_synchronize_rcu_expedited(void);
 75void start_poll_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp);
 76void cond_synchronize_rcu_expedited(unsigned long oldstate);
 77void cond_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp);
 78unsigned long get_state_synchronize_rcu(void);
 79void get_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp);
 80unsigned long start_poll_synchronize_rcu(void);
 81void start_poll_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp);
 82bool poll_state_synchronize_rcu(unsigned long oldstate);
 83bool poll_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp);
 84void cond_synchronize_rcu(unsigned long oldstate);
 85void cond_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp);
 86
 87#ifdef CONFIG_PROVE_RCU
 88void rcu_irq_exit_check_preempt(void);
 89#else
 90static inline void rcu_irq_exit_check_preempt(void) { }
 91#endif
 92
 93struct task_struct;
 94void rcu_preempt_deferred_qs(struct task_struct *t);
 95
 96void exit_rcu(void);
 97
 98void rcu_scheduler_starting(void);
 99extern int rcu_scheduler_active;
100void rcu_end_inkernel_boot(void);
101bool rcu_inkernel_boot_has_ended(void);
102bool rcu_is_watching(void);
103#ifndef CONFIG_PREEMPT_RCU
104void rcu_all_qs(void);
105#endif
106
107/* RCUtree hotplug events */
108int rcutree_prepare_cpu(unsigned int cpu);
109int rcutree_online_cpu(unsigned int cpu);
110void rcutree_report_cpu_starting(unsigned int cpu);
111
112#ifdef CONFIG_HOTPLUG_CPU
113int rcutree_dead_cpu(unsigned int cpu);
114int rcutree_dying_cpu(unsigned int cpu);
115int rcutree_offline_cpu(unsigned int cpu);
116#else
117#define rcutree_dead_cpu NULL
118#define rcutree_dying_cpu NULL
119#define rcutree_offline_cpu NULL
120#endif
121
122void rcutree_migrate_callbacks(int cpu);
123
124/* Called from hotplug and also arm64 early secondary boot failure */
125void rcutree_report_cpu_dead(void);
126
127#endif /* __LINUX_RCUTREE_H */