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 <[email protected]> 21 * Paul E. McKenney <[email protected]> Hierarchical algorithm 22 * 23 * Based on the original work by Paul McKenney <[email protected]> 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 33 struct notifier_block; 34 35 extern void rcu_sched_qs(int cpu); 36 extern void rcu_bh_qs(int cpu); 37 extern int rcu_cpu_notify(struct notifier_block *self, 38 unsigned long action, void *hcpu); 39 extern int rcu_needs_cpu(int cpu); 40 extern int rcu_expedited_torture_stats(char *page); 41 42 #ifdef CONFIG_TREE_PREEMPT_RCU 43 44 extern void __rcu_read_lock(void); 45 extern void __rcu_read_unlock(void); 46 extern void exit_rcu(void); 47 48 #else /* #ifdef CONFIG_TREE_PREEMPT_RCU */ 49 50 static inline void __rcu_read_lock(void) 51 { 52 preempt_disable(); 53 } 54 55 static inline void __rcu_read_unlock(void) 56 { 57 preempt_enable(); 58 } 59 60 #define __synchronize_sched() synchronize_rcu() 61 62 static inline void exit_rcu(void) 63 { 64 } 65 66 #endif /* #else #ifdef CONFIG_TREE_PREEMPT_RCU */ 67 68 static inline void __rcu_read_lock_bh(void) 69 { 70 local_bh_disable(); 71 } 72 static inline void __rcu_read_unlock_bh(void) 73 { 74 local_bh_enable(); 75 } 76 77 extern void call_rcu_sched(struct rcu_head *head, 78 void (*func)(struct rcu_head *rcu)); 79 extern void synchronize_rcu_expedited(void); 80 81 static inline void synchronize_rcu_bh_expedited(void) 82 { 83 synchronize_sched_expedited(); 84 } 85 86 extern void __rcu_init(void); 87 extern void rcu_check_callbacks(int cpu, int user); 88 89 extern long rcu_batches_completed(void); 90 extern long rcu_batches_completed_bh(void); 91 extern long rcu_batches_completed_sched(void); 92 93 #ifdef CONFIG_NO_HZ 94 void rcu_enter_nohz(void); 95 void rcu_exit_nohz(void); 96 #else /* CONFIG_NO_HZ */ 97 static inline void rcu_enter_nohz(void) 98 { 99 } 100 static inline void rcu_exit_nohz(void) 101 { 102 } 103 #endif /* CONFIG_NO_HZ */ 104 105 /* A context switch is a grace period for RCU-sched and RCU-bh. */ 106 static inline int rcu_blocking_is_gp(void) 107 { 108 return num_online_cpus() == 1; 109 } 110 111 #endif /* __LINUX_RCUTREE_H */ 112