/*
   * 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, you can access it online at
   * http://www.gnu.org/licenses/gpl-2.0.html.

   *
   * Copyright (C) IBM Corporation, 2006

   * Copyright (C) Fujitsu, 2012

   *
   * Author: Paul McKenney <paulmck@us.ibm.com>

   *	   Lai Jiangshan <laijs@cn.fujitsu.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>

  #include <linux/rcupdate.h>

  #include <linux/workqueue.h>

  #include <linux/rcu_segcblist.h>

  struct srcu_struct;

  #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_DEP_MAP_INIT(srcu_name)	.dep_map = { .name = #srcu_name },

  #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */

  int init_srcu_struct(struct srcu_struct *sp);

  #define __SRCU_DEP_MAP_INIT(srcu_name)

  #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */

  #ifdef CONFIG_TINY_SRCU
  #include <linux/srcutiny.h>
  #elif defined(CONFIG_TREE_SRCU)
  #include <linux/srcutree.h>

  #elif defined(CONFIG_SRCU)

  #error "Unknown SRCU implementation specified to kernel configuration"

  #else

  /* Dummy definition for things like notifiers.  Actual use gets link error. */
  struct srcu_struct { };

  #endif

  void call_srcu(struct srcu_struct *sp, struct rcu_head *head,
  		void (*func)(struct rcu_head *head));

  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);

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

   * @sp: The srcu_struct structure to check

   *

   * 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.

   *

   * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot
   * and while lockdep is disabled.
   *

   * Note that SRCU is based on its own statemachine and it doesn't
   * relies on normal RCU, it can be called from the CPU which
   * is in the idle loop from an RCU point of view or offline.

   */
  static inline int srcu_read_lock_held(struct srcu_struct *sp)
  {

  	if (!debug_lockdep_rcu_enabled())

  		return 1;

  	return lock_is_held(&sp->dep_map);

  }
  
  #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_check - fetch SRCU-protected pointer for later dereferencing
   * @p: the pointer to fetch and protect for later dereferencing
   * @sp: pointer to the srcu_struct, which is used to check that we
   *	really are in an SRCU read-side critical section.
   * @c: condition to check for update-side use

   *

   * If PROVE_RCU is enabled, invoking this outside of an RCU read-side
   * critical section will result in an RCU-lockdep splat, unless @c evaluates
   * to 1.  The @c argument will normally be a logical expression containing
   * lockdep_is_held() calls.

   */

  #define srcu_dereference_check(p, sp, c) \

  	__rcu_dereference_check((p), (c) || srcu_read_lock_held(sp), __rcu)

  
  /**
   * srcu_dereference - fetch SRCU-protected pointer for later dereferencing
   * @p: the pointer to fetch and protect for later dereferencing
   * @sp: pointer to the srcu_struct, which is used to check that we
   *	really are in an SRCU read-side critical section.
   *
   * Makes rcu_dereference_check() do the dirty work.  If PROVE_RCU
   * is enabled, invoking this outside of an RCU read-side critical
   * section will result in an RCU-lockdep splat.
   */
  #define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0)

  
  /**

   * 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.  However, it is illegal to
   * call anything that waits on an SRCU grace period for the same
   * srcu_struct, whether directly or indirectly.  Please note that
   * one way to indirectly wait on an SRCU grace period is to acquire
   * a mutex that is held elsewhere while calling synchronize_srcu() or
   * synchronize_srcu_expedited().

   *
   * Note that srcu_read_lock() and the matching srcu_read_unlock() must
   * occur in the same context, for example, it is illegal to invoke
   * srcu_read_unlock() in an irq handler if the matching srcu_read_lock()
   * was invoked in process context.

   */
  static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
  {

  	int retval;

  	retval = __srcu_read_lock(sp);

  	rcu_lock_acquire(&(sp)->dep_map);

  	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)
  {

  	rcu_lock_release(&(sp)->dep_map);

  	__srcu_read_unlock(sp, idx);
  }

  /**
   * smp_mb__after_srcu_read_unlock - ensure full ordering after srcu_read_unlock
   *
   * Converts the preceding srcu_read_unlock into a two-way memory barrier.
   *
   * Call this after srcu_read_unlock, to guarantee that all memory operations
   * that occur after smp_mb__after_srcu_read_unlock will appear to happen after
   * the preceding srcu_read_unlock.
   */
  static inline void smp_mb__after_srcu_read_unlock(void)
  {
  	/* __srcu_read_unlock has smp_mb() internally so nothing to do here. */
  }

  #endif