/*
 * 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>
#include <linux/rcupdate.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 
};

#ifndef CONFIG_PREEMPT
#define srcu_barrier() barrier()
#else 
#define srcu_barrier()
#endif 

#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); \
})

#else 

int init_srcu_struct(struct srcu_struct *sp);

#endif 

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

static inline int srcu_read_lock_held(struct srcu_struct *sp)
{
	if (!debug_lockdep_rcu_enabled())
		return 1;
	if (rcu_is_cpu_idle())
		return 0;
	if (!rcu_lockdep_current_cpu_online())
		return 0;
	return lock_is_held(&sp->dep_map);
}

#else 

static inline int srcu_read_lock_held(struct srcu_struct *sp)
{
	return 1;
}

#endif 

#define srcu_dereference_check(p, sp, c) \
	__rcu_dereference_check((p), srcu_read_lock_held(sp) || (c), __rcu)

#define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0)

static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp)
{
	int retval = __srcu_read_lock(sp);

	rcu_lock_acquire(&(sp)->dep_map);
	rcu_lockdep_assert(!rcu_is_cpu_idle(),
			   "srcu_read_lock() used illegally while idle");
	return retval;
}

static inline void srcu_read_unlock(struct srcu_struct *sp, int idx)
	__releases(sp)
{
	rcu_lockdep_assert(!rcu_is_cpu_idle(),
			   "srcu_read_unlock() used illegally while idle");
	rcu_lock_release(&(sp)->dep_map);
	__srcu_read_unlock(sp, idx);
}

static inline int srcu_read_lock_raw(struct srcu_struct *sp)
{
	unsigned long flags;
	int ret;

	local_irq_save(flags);
	ret =  __srcu_read_lock(sp);
	local_irq_restore(flags);
	return ret;
}

static inline void srcu_read_unlock_raw(struct srcu_struct *sp, int idx)
{
	unsigned long flags;

	local_irq_save(flags);
	__srcu_read_unlock(sp, idx);
	local_irq_restore(flags);
}

#endif