linux/include/linux/rcutree.h
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   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
  33extern void rcu_init(void);
  34extern void rcu_note_context_switch(int cpu);
  35extern int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies);
  36extern 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 */
  43static inline void rcu_virt_note_context_switch(int cpu)
  44{
  45        rcu_note_context_switch(cpu);
  46}
  47
  48extern void synchronize_rcu_bh(void);
  49extern void synchronize_sched_expedited(void);
  50extern void synchronize_rcu_expedited(void);
  51
  52void 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 */
  70static inline void synchronize_rcu_bh_expedited(void)
  71{
  72        synchronize_sched_expedited();
  73}
  74
  75extern void rcu_barrier(void);
  76extern void rcu_barrier_bh(void);
  77extern void rcu_barrier_sched(void);
  78
  79extern unsigned long rcutorture_testseq;
  80extern unsigned long rcutorture_vernum;
  81extern long rcu_batches_completed(void);
  82extern long rcu_batches_completed_bh(void);
  83extern long rcu_batches_completed_sched(void);
  84
  85extern void rcu_force_quiescent_state(void);
  86extern void rcu_bh_force_quiescent_state(void);
  87extern void rcu_sched_force_quiescent_state(void);
  88
  89extern void rcu_scheduler_starting(void);
  90extern int rcu_scheduler_active __read_mostly;
  91
  92#endif /* __LINUX_RCUTREE_H */
  93
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