LXR linux/include/linux/rcutree.h

   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
  33void rcu_note_context_switch(int cpu);
  34int rcu_needs_cpu(int cpu, unsigned long *delta_jiffies);
  35void rcu_cpu_stall_reset(void);
  36
  37/*
  38 * Note a virtualization-based context switch.  This is simply a
  39 * wrapper around rcu_note_context_switch(), which allows TINY_RCU
  40 * to save a few bytes.
  41 */
  42static inline void rcu_virt_note_context_switch(int cpu)
  43{
  44        rcu_note_context_switch(cpu);
  45}
  46
  47void synchronize_rcu_bh(void);
  48void synchronize_sched_expedited(void);
  49void synchronize_rcu_expedited(void);
  50
  51void kfree_call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
  52
  53/**
  54 * synchronize_rcu_bh_expedited - Brute-force RCU-bh grace period
  55 *
  56 * Wait for an RCU-bh grace period to elapse, but use a "big hammer"
  57 * approach to force the grace period to end quickly.  This consumes
  58 * significant time on all CPUs and is unfriendly to real-time workloads,
  59 * so is thus not recommended for any sort of common-case code.  In fact,
  60 * if you are using synchronize_rcu_bh_expedited() in a loop, please
  61 * restructure your code to batch your updates, and then use a single
  62 * synchronize_rcu_bh() instead.
  63 *
  64 * Note that it is illegal to call this function while holding any lock
  65 * that is acquired by a CPU-hotplug notifier.  And yes, it is also illegal
  66 * to call this function from a CPU-hotplug notifier.  Failing to observe
  67 * these restriction will result in deadlock.
  68 */
  69static inline void synchronize_rcu_bh_expedited(void)
  70{
  71        synchronize_sched_expedited();
  72}
  73
  74void rcu_barrier(void);
  75void rcu_barrier_bh(void);
  76void rcu_barrier_sched(void);
  77
  78extern unsigned long rcutorture_testseq;
  79extern unsigned long rcutorture_vernum;
  80long rcu_batches_completed(void);
  81long rcu_batches_completed_bh(void);
  82long rcu_batches_completed_sched(void);
  83
  84void rcu_force_quiescent_state(void);
  85void rcu_bh_force_quiescent_state(void);
  86void rcu_sched_force_quiescent_state(void);
  87
  88void exit_rcu(void);
  89
  90void rcu_scheduler_starting(void);
  91extern int rcu_scheduler_active __read_mostly;
  92
  93bool rcu_is_watching(void);
  94
  95#endif /* __LINUX_RCUTREE_H */
  96