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 extern void rcu_init(void); 34 extern void rcu_note_context_switch(int cpu); 35 extern int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies); 36 extern void rcu_cpu_stall_reset(void); 37 38 /* 39 * Note a virtualization-based context switch. This is simply a 40 * wrapper around rcu_note_context_switch(), which allows TINY_RCU 41 * to save a few bytes. 42 */ 43 static inline void rcu_virt_note_context_switch(int cpu) 44 { 45 rcu_note_context_switch(cpu); 46 } 47 48 extern void synchronize_rcu_bh(void); 49 extern void synchronize_sched_expedited(void); 50 extern void synchronize_rcu_expedited(void); 51 52 void kfree_call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu)); 53 54 /** 55 * synchronize_rcu_bh_expedited - Brute-force RCU-bh grace period 56 * 57 * Wait for an RCU-bh grace period to elapse, but use a "big hammer" 58 * approach to force the grace period to end quickly. This consumes 59 * significant time on all CPUs and is unfriendly to real-time workloads, 60 * so is thus not recommended for any sort of common-case code. In fact, 61 * if you are using synchronize_rcu_bh_expedited() in a loop, please 62 * restructure your code to batch your updates, and then use a single 63 * synchronize_rcu_bh() instead. 64 * 65 * Note that it is illegal to call this function while holding any lock 66 * that is acquired by a CPU-hotplug notifier. And yes, it is also illegal 67 * to call this function from a CPU-hotplug notifier. Failing to observe 68 * these restriction will result in deadlock. 69 */ 70 static inline void synchronize_rcu_bh_expedited(void) 71 { 72 synchronize_sched_expedited(); 73 } 74 75 extern void rcu_barrier(void); 76 extern void rcu_barrier_bh(void); 77 extern void rcu_barrier_sched(void); 78 79 extern unsigned long rcutorture_testseq; 80 extern unsigned long rcutorture_vernum; 81 extern long rcu_batches_completed(void); 82 extern long rcu_batches_completed_bh(void); 83 extern long rcu_batches_completed_sched(void); 84 85 extern void rcu_force_quiescent_state(void); 86 extern void rcu_bh_force_quiescent_state(void); 87 extern void rcu_sched_force_quiescent_state(void); 88 89 extern void rcu_scheduler_starting(void); 90 extern int rcu_scheduler_active __read_mostly; 91 92 #endif /* __LINUX_RCUTREE_H */ 93