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
  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 */