urcu-pointer.h

   1 #ifndef _URCU_POINTER_H
   2 #define _URCU_POINTER_H
   3
   4 /*
   5  * urcu-pointer.h
   6  *
   7  * Userspace RCU header. Operations on pointers.
   8  *
   9  * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
  10  * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
  11  *
  12  * This library is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU Lesser General Public
  14  * License as published by the Free Software Foundation; either
  15  * version 2.1 of the License, or (at your option) any later version.
  16  *
  17  * This library is distributed in the hope that it will be useful,
  18  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20  * Lesser General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Lesser General Public
  23  * License along with this library; if not, write to the Free Software
  24  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  25  *
  26  * IBM's contributions to this file may be relicensed under LGPLv2 or later.
  27  */
  28
  29 #include <urcu/compiler.h>
  30 #include <urcu/arch.h>
  31 #include <urcu/uatomic_arch.h>
  32
  33 #ifdef _LGPL_SOURCE
  34
  35 #include <urcu-pointer-static.h>
  36
  37 /*
  38  * rcu_dereference(ptr)
  39  *
  40  * Fetch a RCU-protected pointer. Typically used to copy the variable ptr to a
  41  * local variable.
  42  */
  43 #define rcu_dereference         _rcu_dereference
  44
  45 /*
  46  * rcu_cmpxchg_pointer(type **ptr, type *new, type *old)
  47  * type *rcu_xchg_pointer(type **ptr, type *new)
  48  * type *rcu_set_pointer(type **ptr, type *new)
  49  *
  50  * RCU pointer updates.
  51  * @ptr: address of the pointer to modify
  52  * @new: new pointer value
  53  * @old: old pointer value (expected)
  54  *
  55  * return: old pointer value
  56  */
  57 #define rcu_cmpxchg_pointer     _rcu_cmpxchg_pointer
  58 #define rcu_xchg_pointer        _rcu_xchg_pointer
  59 #define rcu_set_pointer         _rcu_set_pointer
  60
  61 #else /* !_LGPL_SOURCE */
  62
  63 extern void *rcu_dereference_sym(void *p);
  64 #define rcu_dereference(p)                                                   \
  65         ({                                                                   \
  66                 typeof(p) _________p1 =                                      \
  67                         rcu_dereference_sym((void *)(p));                    \
  68                 (_________p1);                                               \
  69         })
  70
  71 extern void *rcu_cmpxchg_pointer_sym(void **p, void *old, void *_new);
  72 #define rcu_cmpxchg_pointer(p, old, _new)                                    \
  73         ({                                                                   \
  74                 typeof(*p) _________pold = (old);                            \
  75                 typeof(*p) _________pnew = (_new);                           \
  76                 typeof(*p) _________p1 =                                     \
  77                         rcu_cmpxchg_pointer_sym((void **)(p), _________pold, \
  78                                                 _________pnew);              \
  79                 (_________p1);                                               \
  80         })
  81
  82 extern void *rcu_xchg_pointer_sym(void **p, void *v);
  83 #define rcu_xchg_pointer(p, v)                                               \
  84         ({                                                                   \
  85                 typeof(*p) _________pv = (v);                                \
  86                 typeof(*p) _________p1 =                                     \
  87                         rcu_xchg_pointer_sym((void **)(p), _________pv);     \
  88                 (_________p1);                                               \
  89         })
  90
  91 extern void *rcu_set_pointer_sym(void **p, void *v);
  92 #define rcu_set_pointer(p, v)                                                \
  93         ({                                                                   \
  94                 typeof(*p) _________pv = (v);                                \
  95                 typeof(*p) _________p1 =                                     \
  96                         rcu_set_pointer_sym((void **)(p), _________pv);      \
  97         })
  98
  99 #endif /* !_LGPL_SOURCE */
 100
 101 /*
 102  * rcu_assign_pointer(type *ptr, type *new)
 103  *
 104  * Same as rcu_set_pointer, but takes the pointer to assign to rather than its
 105  * address as first parameter. Provided for compatibility with the Linux kernel
 106  * RCU semantic.
 107  */
 108 #define rcu_assign_pointer(p, v)        rcu_set_pointer((&p), (v))
 109
 110 #endif /* _URCU_POINTER_H */