/*
   * Sleepable Read-Copy Update mechanism for mutual exclusion
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
   *
   * Copyright (C) IBM Corporation, 2006
   *
   * Author: Paul McKenney <paulmck@us.ibm.com>
   *
   * For detailed explanation of Read-Copy Update mechanism see -
   * 		Documentation/RCU/ *.txt
   *
   */

  #ifndef _LINUX_SRCU_H
  #define _LINUX_SRCU_H

  #include <linux/mutex.h>

  struct srcu_struct_array {
  	int c[2];
  };
  
  struct srcu_struct {
  	int completed;

  	struct srcu_struct_array __percpu *per_cpu_ref;

  	struct mutex mutex;

  #ifdef CONFIG_DEBUG_LOCK_ALLOC
  	struct lockdep_map dep_map;
  #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */

  };
  
  #ifndef CONFIG_PREEMPT
  #define srcu_barrier() barrier()
  #else /* #ifndef CONFIG_PREEMPT */
  #define srcu_barrier()
  #endif /* #else #ifndef CONFIG_PREEMPT */

  #ifdef CONFIG_DEBUG_LOCK_ALLOC
  
  int __init_srcu_struct(struct srcu_struct *sp, const char *name,
  		       struct lock_class_key *key);
  
  #define init_srcu_struct(sp) \
  ({ \
  	static struct lock_class_key __srcu_key; \
  	\
  	__init_srcu_struct((sp), #sp, &__srcu_key); \
  })
  
  # define srcu_read_acquire(sp) \
  		lock_acquire(&(sp)->dep_map, 0, 0, 2, 1, NULL, _THIS_IP_)
  # define srcu_read_release(sp) \
  		lock_release(&(sp)->dep_map, 1, _THIS_IP_)
  
  #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */

  int init_srcu_struct(struct srcu_struct *sp);

  
  # define srcu_read_acquire(sp)  do { } while (0)
  # define srcu_read_release(sp)  do { } while (0)
  
  #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */

  void cleanup_srcu_struct(struct srcu_struct *sp);

  int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp);
  void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp);

  void synchronize_srcu(struct srcu_struct *sp);

  void synchronize_srcu_expedited(struct srcu_struct *sp);

  long srcu_batches_completed(struct srcu_struct *sp);

  #ifdef CONFIG_DEBUG_LOCK_ALLOC
  
  /**
   * srcu_read_lock_held - might we be in SRCU read-side critical section?
   *

   * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU
   * read-side critical section.  In absence of CONFIG_DEBUG_LOCK_ALLOC,

   * this assumes we are in an SRCU read-side critical section unless it can
   * prove otherwise.
   */
  static inline int srcu_read_lock_held(struct srcu_struct *sp)
  {
  	if (debug_locks)
  		return lock_is_held(&sp->dep_map);
  	return 1;
  }
  
  #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */
  
  static inline int srcu_read_lock_held(struct srcu_struct *sp)
  {
  	return 1;
  }
  
  #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */
  
  /**

   * srcu_dereference - fetch SRCU-protected pointer with checking
   *
   * Makes rcu_dereference_check() do the dirty work.
   */
  #define srcu_dereference(p, sp) \
  		rcu_dereference_check(p, srcu_read_lock_held(sp))
  
  /**

   * srcu_read_lock - register a new reader for an SRCU-protected structure.
   * @sp: srcu_struct in which to register the new reader.
   *
   * Enter an SRCU read-side critical section.  Note that SRCU read-side
   * critical sections may be nested.
   */
  static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
  {
  	int retval = __srcu_read_lock(sp);
  
  	srcu_read_acquire(sp);
  	return retval;
  }
  
  /**
   * srcu_read_unlock - unregister a old reader from an SRCU-protected structure.
   * @sp: srcu_struct in which to unregister the old reader.
   * @idx: return value from corresponding srcu_read_lock().
   *
   * Exit an SRCU read-side critical section.
   */
  static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
  	__releases(sp)
  {
  	srcu_read_release(sp);
  	__srcu_read_unlock(sp, idx);
  }

  #endif