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); 37void kvfree_call_rcu(struct rcu_head *head, void *ptr); 38 39void rcu_barrier(void); 40void rcu_momentary_dyntick_idle(void); 41void kfree_rcu_scheduler_running(void); 42bool rcu_gp_might_be_stalled(void); 43 44struct rcu_gp_oldstate { 45 unsigned long rgos_norm; 46 unsigned long rgos_exp; 47}; 48 49// Maximum number of rcu_gp_oldstate values corresponding to 50// not-yet-completed RCU grace periods. 51#define NUM_ACTIVE_RCU_POLL_FULL_OLDSTATE 4 52 53/** 54 * same_state_synchronize_rcu_full - Are two old-state values identical? 55 * @rgosp1: First old-state value. 56 * @rgosp2: Second old-state value. 57 * 58 * The two old-state values must have been obtained from either 59 * get_state_synchronize_rcu_full(), start_poll_synchronize_rcu_full(), 60 * or get_completed_synchronize_rcu_full(). Returns @true if the two 61 * values are identical and @false otherwise. This allows structures 62 * whose lifetimes are tracked by old-state values to push these values 63 * to a list header, allowing those structures to be slightly smaller. 64 * 65 * Note that equality is judged on a bitwise basis, so that an 66 * @rcu_gp_oldstate structure with an already-completed state in one field 67 * will compare not-equal to a structure with an already-completed state 68 * in the other field. After all, the @rcu_gp_oldstate structure is opaque 69 * so how did such a situation come to pass in the first place? 70 */ 71static inline bool same_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp1, 72 struct rcu_gp_oldstate *rgosp2) 73{ 74 return rgosp1->rgos_norm == rgosp2->rgos_norm && rgosp1->rgos_exp == rgosp2->rgos_exp; 75} 76 77unsigned long start_poll_synchronize_rcu_expedited(void); 78void start_poll_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp); 79void cond_synchronize_rcu_expedited(unsigned long oldstate); 80void cond_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp); 81unsigned long get_state_synchronize_rcu(void); 82void get_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp); 83unsigned long start_poll_synchronize_rcu(void); 84void start_poll_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp); 85bool poll_state_synchronize_rcu(unsigned long oldstate); 86bool poll_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp); 87void cond_synchronize_rcu(unsigned long oldstate); 88void cond_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp); 89 90#ifdef CONFIG_PROVE_RCU 91void rcu_irq_exit_check_preempt(void); 92#else 93static inline void rcu_irq_exit_check_preempt(void) { } 94#endif 95 96struct task_struct; 97void rcu_preempt_deferred_qs(struct task_struct *t); 98 99void exit_rcu(void); 100 101void rcu_scheduler_starting(void); 102extern int rcu_scheduler_active; 103void rcu_end_inkernel_boot(void); 104bool rcu_inkernel_boot_has_ended(void); 105bool rcu_is_watching(void); 106#ifndef CONFIG_PREEMPTION 107void rcu_all_qs(void); 108#endif 109 110/* RCUtree hotplug events */ 111int rcutree_prepare_cpu(unsigned int cpu); 112int rcutree_online_cpu(unsigned int cpu); 113void rcutree_report_cpu_starting(unsigned int cpu); 114 115#ifdef CONFIG_HOTPLUG_CPU 116int rcutree_dead_cpu(unsigned int cpu); 117int rcutree_dying_cpu(unsigned int cpu); 118int rcutree_offline_cpu(unsigned int cpu); 119#else 120#define rcutree_dead_cpu NULL 121#define rcutree_dying_cpu NULL 122#define rcutree_offline_cpu NULL 123#endif 124 125void rcutree_migrate_callbacks(int cpu); 126 127/* Called from hotplug and also arm64 early secondary boot failure */ 128void rcutree_report_cpu_dead(void); 129 130#endif /* __LINUX_RCUTREE_H */ 131