include/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@efficios.com>
  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.h>
  32
  33 #ifdef __cplusplus
  34 extern "C" {
  35 #endif
  36
  37 #if defined(_LGPL_SOURCE) || defined(URCU_INLINE_SMALL_FUNCTIONS)
  38
  39 #include <urcu/static/pointer.h>
  40
  41 /*
  42  * rcu_dereference(ptr)
  43  *
  44  * Fetch a RCU-protected pointer. Typically used to copy the variable ptr to a
  45  * local variable.
  46  */
  47 #define rcu_dereference         _rcu_dereference
  48
  49 /*
  50  * type *rcu_cmpxchg_pointer(type **ptr, type *new, type *old)
  51  * type *rcu_xchg_pointer(type **ptr, type *new)
  52  * void rcu_set_pointer(type **ptr, type *new)
  53  *
  54  * RCU pointer updates.
  55  * @ptr: address of the pointer to modify
  56  * @new: new pointer value
  57  * @old: old pointer value (expected)
  58  *
  59  * return: old pointer value
  60  */
  61 #define rcu_cmpxchg_pointer     _rcu_cmpxchg_pointer
  62 #define rcu_xchg_pointer        _rcu_xchg_pointer
  63 #define rcu_set_pointer         _rcu_set_pointer
  64
  65 #else /* !(defined(_LGPL_SOURCE) || defined(URCU_INLINE_SMALL_FUNCTIONS)) */
  66
  67 extern void *rcu_dereference_sym(void *p);
  68 #define rcu_dereference(p)                                                   \
  69         __extension__                                                        \
  70         ({                                                                   \
  71                 __typeof__(p) _________p1 =     URCU_FORCE_CAST(__typeof__(p), \
  72                         rcu_dereference_sym(URCU_FORCE_CAST(void *, p)));    \
  73                 (_________p1);                                               \
  74         })
  75
  76 extern void *rcu_cmpxchg_pointer_sym(void **p, void *old, void *_new);
  77 #define rcu_cmpxchg_pointer(p, old, _new)                                    \
  78         __extension__                                                        \
  79         ({                                                                   \
  80                 __typeof__(*(p)) _________pold = (old);                      \
  81                 __typeof__(*(p)) _________pnew = (_new);                     \
  82                 __typeof__(*(p)) _________p1 = URCU_FORCE_CAST(__typeof__(*(p)), \
  83                         rcu_cmpxchg_pointer_sym(URCU_FORCE_CAST(void **, p), \
  84                                                 _________pold,               \
  85                                                 _________pnew));             \
  86                 (_________p1);                                               \
  87         })
  88
  89 extern void *rcu_xchg_pointer_sym(void **p, void *v);
  90 #define rcu_xchg_pointer(p, v)                                               \
  91         __extension__                                                        \
  92         ({                                                                   \
  93                 __typeof__(*(p)) _________pv = (v);                          \
  94                 __typeof__(*(p)) _________p1 = URCU_FORCE_CAST(__typeof__(*(p)), \
  95                         rcu_xchg_pointer_sym(URCU_FORCE_CAST(void **, p),    \
  96                                              _________pv));                  \
  97                 (_________p1);                                               \
  98         })
  99
 100 /*
 101  * Note: rcu_set_pointer_sym returns @v because we don't want to break
 102  * the ABI. At the API level, rcu_set_pointer() now returns void. Use of
 103  * the return value is therefore deprecated, and will cause a build
 104  * error.
 105  */
 106 extern void *rcu_set_pointer_sym(void **p, void *v);
 107 #define rcu_set_pointer(p, v)                                                \
 108         do {                                                                 \
 109                 __typeof__(*(p)) _________pv = (v);                          \
 110                 (void) rcu_set_pointer_sym(URCU_FORCE_CAST(void **, p),      \
 111                                             _________pv);                    \
 112         } while (0)
 113
 114 #endif /* !(defined(_LGPL_SOURCE) || defined(URCU_INLINE_SMALL_FUNCTIONS)) */
 115
 116 /*
 117  * void rcu_assign_pointer(type *ptr, type *new)
 118  *
 119  * Same as rcu_set_pointer, but takes the pointer to assign to rather than its
 120  * address as first parameter. Provided for compatibility with the Linux kernel
 121  * RCU semantic.
 122  */
 123 #define rcu_assign_pointer(p, v)        rcu_set_pointer((&p), (v))
 124
 125 #ifdef __cplusplus
 126 }
 127 #endif
 128
 129 #endif /* _URCU_POINTER_H */