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 20 void rcu_softirq_qs(void); 21 void rcu_note_context_switch(bool preempt); 22 int rcu_needs_cpu(void); 23 void rcu_cpu_stall_reset(void); 24 25 /* 26 * Note a virtualization-based context switch. This is simply a 27 * wrapper around rcu_note_context_switch(), which allows TINY_RCU 28 * to save a few bytes. The caller must have disabled interrupts. 29 */ 30 static inline void rcu_virt_note_context_switch(int cpu) 31 { 32 rcu_note_context_switch(false); 33 } 34 35 void synchronize_rcu_expedited(void); 36 void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func); 37 38 void rcu_barrier(void); 39 bool rcu_eqs_special_set(int cpu); 40 void rcu_momentary_dyntick_idle(void); 41 void kfree_rcu_scheduler_running(void); 42 bool rcu_gp_might_be_stalled(void); 43 44 struct 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 */ 71 static 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 77 unsigned long start_poll_synchronize_rcu_expedited(void); 78 void start_poll_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp); 79 void cond_synchronize_rcu_expedited(unsigned long oldstate); 80 void cond_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp); 81 unsigned long get_state_synchronize_rcu(void); 82 void get_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp); 83 unsigned long start_poll_synchronize_rcu(void); 84 void start_poll_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp); 85 bool poll_state_synchronize_rcu(unsigned long oldstate); 86 bool poll_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp); 87 void cond_synchronize_rcu(unsigned long oldstate); 88 void cond_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp); 89 90 bool rcu_is_idle_cpu(int cpu); 91 92 #ifdef CONFIG_PROVE_RCU 93 void rcu_irq_exit_check_preempt(void); 94 #else 95 static inline void rcu_irq_exit_check_preempt(void) { } 96 #endif 97 98 struct task_struct; 99 void rcu_preempt_deferred_qs(struct task_struct *t); 100 101 void exit_rcu(void); 102 103 void rcu_scheduler_starting(void); 104 extern int rcu_scheduler_active; 105 void rcu_end_inkernel_boot(void); 106 bool rcu_inkernel_boot_has_ended(void); 107 bool rcu_is_watching(void); 108 #ifndef CONFIG_PREEMPTION 109 void rcu_all_qs(void); 110 #endif 111 112 /* RCUtree hotplug events */ 113 int rcutree_prepare_cpu(unsigned int cpu); 114 int rcutree_online_cpu(unsigned int cpu); 115 int rcutree_offline_cpu(unsigned int cpu); 116 int rcutree_dead_cpu(unsigned int cpu); 117 int rcutree_dying_cpu(unsigned int cpu); 118 void rcu_cpu_starting(unsigned int cpu); 119 120 #endif /* __LINUX_RCUTREE_H */ 121