1/* 2 * Read-Copy Update mechanism for mutual exclusion (tree-based version) 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License as published by 6 * the Free Software Foundation; either version 2 of the License, or 7 * (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 * 14 * You should have received a copy of the GNU General Public License 15 * along with this program; if not, write to the Free Software 16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 17 * 18 * Copyright IBM Corporation, 2008 19 * 20 * Author: Dipankar Sarma <dipankar@in.ibm.com> 21 * Paul E. McKenney <paulmck@linux.vnet.ibm.com> Hierarchical algorithm 22 * 23 * Based on the original work by Paul McKenney <paulmck@us.ibm.com> 24 * and inputs from Rusty Russell, Andrea Arcangeli and Andi Kleen. 25 * 26 * For detailed explanation of Read-Copy Update mechanism see - 27 * Documentation/RCU 28 */ 29 30#ifndef __LINUX_RCUTREE_H 31#define __LINUX_RCUTREE_H 32 33struct notifier_block; 34 35extern void rcu_sched_qs(int cpu); 36extern void rcu_bh_qs(int cpu); 37extern void rcu_note_context_switch(int cpu); 38extern int rcu_needs_cpu(int cpu); 39 40#ifdef CONFIG_TREE_PREEMPT_RCU 41 42extern void __rcu_read_lock(void); 43extern void __rcu_read_unlock(void); 44extern void synchronize_rcu(void); 45extern void exit_rcu(void); 46 47/* 48 * Defined as macro as it is a very low level header 49 * included from areas that don't even know about current 50 */ 51#define rcu_preempt_depth() (current->rcu_read_lock_nesting) 52 53#else /* #ifdef CONFIG_TREE_PREEMPT_RCU */ 54 55static inline void __rcu_read_lock(void) 56{ 57 preempt_disable(); 58} 59 60static inline void __rcu_read_unlock(void) 61{ 62 preempt_enable(); 63} 64 65#define synchronize_rcu synchronize_sched 66 67static inline void exit_rcu(void) 68{ 69} 70 71static inline int rcu_preempt_depth(void) 72{ 73 return 0; 74} 75 76#endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */ 77 78static inline void __rcu_read_lock_bh(void) 79{ 80 local_bh_disable(); 81} 82static inline void __rcu_read_unlock_bh(void) 83{ 84 local_bh_enable(); 85} 86 87extern void call_rcu_sched(struct rcu_head *head, 88 void (*func)(struct rcu_head *rcu)); 89extern void synchronize_rcu_bh(void); 90extern void synchronize_sched(void); 91extern void synchronize_rcu_expedited(void); 92 93static inline void synchronize_rcu_bh_expedited(void) 94{ 95 synchronize_sched_expedited(); 96} 97 98extern void rcu_check_callbacks(int cpu, int user); 99 100extern long rcu_batches_completed(void); 101extern long rcu_batches_completed_bh(void); 102extern long rcu_batches_completed_sched(void); 103extern void rcu_force_quiescent_state(void); 104extern void rcu_bh_force_quiescent_state(void); 105extern void rcu_sched_force_quiescent_state(void); 106 107#ifdef CONFIG_NO_HZ 108void rcu_enter_nohz(void); 109void rcu_exit_nohz(void); 110#else /* CONFIG_NO_HZ */ 111static inline void rcu_enter_nohz(void) 112{ 113} 114static inline void rcu_exit_nohz(void) 115{ 116} 117#endif /* CONFIG_NO_HZ */ 118 119/* A context switch is a grace period for RCU-sched and RCU-bh. */ 120static inline int rcu_blocking_is_gp(void) 121{ 122 return num_online_cpus() == 1; 123} 124 125extern void rcu_scheduler_starting(void); 126extern int rcu_scheduler_active __read_mostly; 127 128#endif /* __LINUX_RCUTREE_H */ 129