net/tipc/ref.h

   1 /*
   2  * net/tipc/ref.h: Include file for TIPC object registry code
   3  *
   4  * Copyright (c) 2003-2005, Ericsson Research Canada
   5  * Copyright (c) 2005, Wind River Systems
   6  * Copyright (c) 2005-2006, Ericsson AB
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions are met:
  11  *
  12  * Redistributions of source code must retain the above copyright notice, this
  13  * list of conditions and the following disclaimer.
  14  * Redistributions in binary form must reproduce the above copyright notice,
  15  * this list of conditions and the following disclaimer in the documentation
  16  * and/or other materials provided with the distribution.
  17  * Neither the names of the copyright holders nor the names of its
  18  * contributors may be used to endorse or promote products derived from this
  19  * software without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  22  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  25  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  26  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  27  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  30  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  31  * POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #ifndef _TIPC_REF_H
  35 #define _TIPC_REF_H
  36
  37 /**
  38  * struct reference - TIPC object reference entry
  39  * @object: pointer to object associated with reference entry
  40  * @lock: spinlock controlling access to object
  41  * @data: reference value associated with object (or link to next unused entry)
  42  */
  43
  44 struct reference {
  45         void *object;
  46         spinlock_t lock;
  47         union {
  48                 u32 next_plus_upper;
  49                 u32 reference;
  50         } data;
  51 };
  52
  53 /**
  54  * struct ref_table - table of TIPC object reference entries
  55  * @entries: pointer to array of reference entries
  56  * @index_mask: bitmask for array index portion of reference values
  57  * @first_free: array index of first unused object reference entry
  58  * @last_free: array index of last unused object reference entry
  59  */
  60
  61 struct ref_table {
  62         struct reference *entries;
  63         u32 index_mask;
  64         u32 first_free;
  65         u32 last_free;
  66 };
  67
  68 extern struct ref_table ref_table;
  69
  70 int ref_table_init(u32 requested_size, u32 start);
  71 void ref_table_stop(void);
  72
  73 u32 ref_acquire(void *object, spinlock_t **lock);
  74 void ref_discard(u32 ref);
  75
  76
  77 /**
  78  * ref_lock - lock referenced object and return pointer to it
  79  */
  80
  81 static inline void *ref_lock(u32 ref)
  82 {
  83         if (likely(ref_table.entries)) {
  84                 struct reference *r =
  85                         &ref_table.entries[ref & ref_table.index_mask];
  86
  87                 spin_lock_bh(&r->lock);
  88                 if (likely(r->data.reference == ref))
  89                         return r->object;
  90                 spin_unlock_bh(&r->lock);
  91         }
  92         return 0;
  93 }
  94
  95 /**
  96  * ref_unlock - unlock referenced object
  97  */
  98
  99 static inline void ref_unlock(u32 ref)
 100 {
 101         if (likely(ref_table.entries)) {
 102                 struct reference *r =
 103                         &ref_table.entries[ref & ref_table.index_mask];
 104
 105                 if (likely(r->data.reference == ref))
 106                         spin_unlock_bh(&r->lock);
 107                 else
 108                         err("ref_unlock() invoked using obsolete reference\n");
 109         }
 110 }
 111
 112 /**
 113  * ref_deref - return pointer referenced object (without locking it)
 114  */
 115
 116 static inline void *ref_deref(u32 ref)
 117 {
 118         if (likely(ref_table.entries)) {
 119                 struct reference *r =
 120                         &ref_table.entries[ref & ref_table.index_mask];
 121
 122                 if (likely(r->data.reference == ref))
 123                         return r->object;
 124         }
 125         return 0;
 126 }
 127
 128 #endif