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/*
 * net/tipc/ref.c: TIPC object registry code
 *
 * Copyright (c) 1991-2006, Ericsson AB
 * Copyright (c) 2004-2007, Wind River Systems
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "core.h"
#include "ref.h"

/**
 * struct reference - TIPC object reference entry
 * @object: pointer to object associated with reference entry
 * @lock: spinlock controlling access to object
 * @ref: reference value for object (combines instance & array index info)
 */

struct reference {
	void *object;
	spinlock_t lock;
	u32 ref;
};

/**
 * struct tipc_ref_table - table of TIPC object reference entries
 * @entries: pointer to array of reference entries
 * @capacity: array index of first unusable entry
 * @init_point: array index of first uninitialized entry
 * @first_free: array index of first unused object reference entry
 * @last_free: array index of last unused object reference entry
 * @index_mask: bitmask for array index portion of reference values
 * @start_mask: initial value for instance value portion of reference values
 */

struct ref_table {
	struct reference *entries;
	u32 capacity;
	u32 init_point;
	u32 first_free;
	u32 last_free;
	u32 index_mask;
	u32 start_mask;
};

/*
 * Object reference table consists of 2**N entries.
 *
 * State	Object ptr	Reference
 * -----        ----------      ---------
 * In use        non-NULL       XXXX|own index
 *				(XXXX changes each time entry is acquired)
 * Free            NULL         YYYY|next free index
 *				(YYYY is one more than last used XXXX)
 * Uninitialized   NULL         0
 *
 * Entry 0 is not used; this allows index 0 to denote the end of the free list.
 *
 * Note that a reference value of 0 does not necessarily indicate that an
 * entry is uninitialized, since the last entry in the free list could also
 * have a reference value of 0 (although this is unlikely).
 */

static struct ref_table tipc_ref_table = { NULL };

static DEFINE_RWLOCK(ref_table_lock);

/**
 * tipc_ref_table_init - create reference table for objects
 */