net/tipc/ref.h

   1 /*
   2  * net/tipc/ref.h: Include file for TIPC object registry code
   3  *
   4  * Copyright (c) 1991-2006, Ericsson AB
   5  * Copyright (c) 2005, Wind River Systems
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the names of the copyright holders nor the names of its
  17  *    contributors may be used to endorse or promote products derived from
  18  *    this software without specific prior written permission.
  19  *
  20  * Alternatively, this software may be distributed under the terms of the
  21  * GNU General Public License ("GPL") version 2 as published by the Free
  22  * Software Foundation.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  25  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  28  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  29  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  30  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  31  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  32  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  33  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  34  * POSSIBILITY OF SUCH DAMAGE.
  35  */
  36
  37 #ifndef _TIPC_REF_H
  38 #define _TIPC_REF_H
  39
  40 /**
  41  * struct reference - TIPC object reference entry
  42  * @object: pointer to object associated with reference entry
  43  * @lock: spinlock controlling access to object
  44  * @data: reference value associated with object (or link to next unused entry)
  45  */
  46
  47 struct reference {
  48         void *object;
  49         spinlock_t lock;
  50         union {
  51                 u32 next_plus_upper;
  52                 u32 reference;
  53         } data;
  54 };
  55
  56 /**
  57  * struct tipc_ref_table - table of TIPC object reference entries
  58  * @entries: pointer to array of reference entries
  59  * @index_mask: bitmask for array index portion of reference values
  60  * @first_free: array index of first unused object reference entry
  61  * @last_free: array index of last unused object reference entry
  62  */
  63
  64 struct ref_table {
  65         struct reference *entries;
  66         u32 index_mask;
  67         u32 first_free;
  68         u32 last_free;
  69 };
  70
  71 extern struct ref_table tipc_ref_table;
  72
  73 int tipc_ref_table_init(u32 requested_size, u32 start);
  74 void tipc_ref_table_stop(void);
  75
  76 u32 tipc_ref_acquire(void *object, spinlock_t **lock);
  77 void tipc_ref_discard(u32 ref);
  78
  79
  80 /**
  81  * tipc_ref_lock - lock referenced object and return pointer to it
  82  */
  83
  84 static inline void *tipc_ref_lock(u32 ref)
  85 {
  86         if (likely(tipc_ref_table.entries)) {
  87                 struct reference *r =
  88                         &tipc_ref_table.entries[ref & tipc_ref_table.index_mask];
  89
  90                 spin_lock_bh(&r->lock);
  91                 if (likely(r->data.reference == ref))
  92                         return r->object;
  93                 spin_unlock_bh(&r->lock);
  94         }
  95         return NULL;
  96 }
  97
  98 /**
  99  * tipc_ref_unlock - unlock referenced object
 100  */
 101
 102 static inline void tipc_ref_unlock(u32 ref)
 103 {
 104         if (likely(tipc_ref_table.entries)) {
 105                 struct reference *r =
 106                         &tipc_ref_table.entries[ref & tipc_ref_table.index_mask];
 107
 108                 if (likely(r->data.reference == ref))
 109                         spin_unlock_bh(&r->lock);
 110                 else
 111                         err("tipc_ref_unlock() invoked using obsolete reference\n");
 112         }
 113 }
 114
 115 /**
 116  * tipc_ref_deref - return pointer referenced object (without locking it)
 117  */
 118
 119 static inline void *tipc_ref_deref(u32 ref)
 120 {
 121         if (likely(tipc_ref_table.entries)) {
 122                 struct reference *r =
 123                         &tipc_ref_table.entries[ref & tipc_ref_table.index_mask];
 124
 125                 if (likely(r->data.reference == ref))
 126                         return r->object;
 127         }
 128         return NULL;
 129 }
 130
 131 #endif