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xianfeng |
/*
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* net/tipc/ref.h: Include file for TIPC object registry code
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*
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* Copyright (c) 1991-2006, Ericsson AB
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* Copyright (c) 2005, Wind River Systems
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the names of the copyright holders nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* Alternatively, this software may be distributed under the terms of the
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* GNU General Public License ("GPL") version 2 as published by the Free
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* Software Foundation.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef _TIPC_REF_H
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#define _TIPC_REF_H
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/**
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* struct reference - TIPC object reference entry
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* @object: pointer to object associated with reference entry
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* @lock: spinlock controlling access to object
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* @data: reference value associated with object (or link to next unused entry)
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*/
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struct reference {
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void *object;
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spinlock_t lock;
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union {
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u32 next_plus_upper;
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u32 reference;
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} data;
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};
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/**
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* struct tipc_ref_table - table of TIPC object reference entries
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* @entries: pointer to array of reference entries
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* @index_mask: bitmask for array index portion of reference values
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* @first_free: array index of first unused object reference entry
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* @last_free: array index of last unused object reference entry
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*/
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struct ref_table {
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struct reference *entries;
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u32 index_mask;
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u32 first_free;
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u32 last_free;
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};
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extern struct ref_table tipc_ref_table;
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int tipc_ref_table_init(u32 requested_size, u32 start);
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void tipc_ref_table_stop(void);
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u32 tipc_ref_acquire(void *object, spinlock_t **lock);
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void tipc_ref_discard(u32 ref);
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/**
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* tipc_ref_lock - lock referenced object and return pointer to it
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*/
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static inline void *tipc_ref_lock(u32 ref)
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{
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if (likely(tipc_ref_table.entries)) {
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struct reference *r =
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&tipc_ref_table.entries[ref & tipc_ref_table.index_mask];
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spin_lock_bh(&r->lock);
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if (likely(r->data.reference == ref))
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return r->object;
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spin_unlock_bh(&r->lock);
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}
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return NULL;
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}
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/**
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* tipc_ref_unlock - unlock referenced object
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*/
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static inline void tipc_ref_unlock(u32 ref)
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{
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if (likely(tipc_ref_table.entries)) {
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struct reference *r =
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&tipc_ref_table.entries[ref & tipc_ref_table.index_mask];
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if (likely(r->data.reference == ref))
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spin_unlock_bh(&r->lock);
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else
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err("tipc_ref_unlock() invoked using obsolete reference\n");
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}
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}
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/**
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* tipc_ref_deref - return pointer referenced object (without locking it)
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*/
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static inline void *tipc_ref_deref(u32 ref)
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{
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if (likely(tipc_ref_table.entries)) {
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struct reference *r =
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&tipc_ref_table.entries[ref & tipc_ref_table.index_mask];
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if (likely(r->data.reference == ref))
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return r->object;
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}
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return NULL;
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}
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#endif
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