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/*
* net/tipc/ref.h: Include file for TIPC object registry code
*
* Copyright (c) 1991-2006, Ericsson AB
* Copyright (c) 2005, 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.
*/
#ifndef _TIPC_REF_H
#define _TIPC_REF_H
/**
* struct reference - TIPC object reference entry
* @object: pointer to object associated with reference entry
* @lock: spinlock controlling access to object
* @data: reference value associated with object (or link to next unused entry)
*/
struct reference {
void *object;
spinlock_t lock;
union {
u32 next_plus_upper;
u32 reference;
} data;
};
/**
* struct ref_table - table of TIPC object reference entries
* @entries: pointer to array of reference entries
* @index_mask: bitmask for array index portion of reference values
* @first_free: array index of first unused object reference entry
* @last_free: array index of last unused object reference entry
*/
struct ref_table {
struct reference *entries;
u32 index_mask;
u32 first_free;
u32 last_free;
};
extern struct ref_table ref_table;
int ref_table_init(u32 requested_size, u32 start);
void ref_table_stop(void);
u32 ref_acquire(void *object, spinlock_t **lock);
void ref_discard(u32 ref);
/**
* ref_lock - lock referenced object and return pointer to it
*/
static inline void *ref_lock(u32 ref)
{
if (likely(ref_table.entries)) {
struct reference *r =
&ref_table.entries[ref & ref_table.index_mask];
spin_lock_bh(&r->lock);
if (likely(r->data.reference == ref))
return r->object;
spin_unlock_bh(&r->lock);
}
return 0;
}
/**
* ref_unlock - unlock referenced object
*/
static inline void ref_unlock(u32 ref)
{
if (likely(ref_table.entries)) {
struct reference *r =
&ref_table.entries[ref & ref_table.index_mask];
if (likely(r->data.reference == ref))
spin_unlock_bh(&r->lock);
else
err("ref_unlock() invoked using obsolete reference\n");
}
}
/**
* ref_deref - return pointer referenced object (without locking it)
*/
static inline void *ref_deref(u32 ref)
{
if (likely(ref_table.entries)) {
struct reference *r =
&ref_table.entries[ref & ref_table.index_mask];
if (likely(r->data.reference == ref))
return r->object;
}
return 0;
}
#endif
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