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 #include <urcu/urcu-checker.h>
  33
  34 #ifdef __cplusplus
  35 extern "C" {
  36 #endif
  37
  38 #if defined(_LGPL_SOURCE) || defined(URCU_INLINE_SMALL_FUNCTIONS)
  39
  40 #include <urcu/static/urcu-pointer.h>
  41
  42 /*
  43  * rcu_dereference(ptr)
  44  *
  45  * Fetch a RCU-protected pointer. Typically used to copy the variable ptr to a
  46  * local variable.
  47  */
  48 #define rcu_dereference(p)                              \
  49         ({                                              \
  50                 rcu_read_ongoing_check_debug(__func__); \
  51                 _rcu_dereference(p);                    \
  52         })
  53
  54 /*
  55  * type *rcu_cmpxchg_pointer(type **ptr, type *new, type *old)
  56  * type *rcu_xchg_pointer(type **ptr, type *new)
  57  * void rcu_set_pointer(type **ptr, type *new)
  58  *
  59  * RCU pointer updates.
  60  * @ptr: address of the pointer to modify
  61  * @new: new pointer value
  62  * @old: old pointer value (expected)
  63  *
  64  * return: old pointer value
  65  */
  66 #define rcu_cmpxchg_pointer     _rcu_cmpxchg_pointer
  67 #define rcu_xchg_pointer        _rcu_xchg_pointer
  68 #define rcu_set_pointer         _rcu_set_pointer
  69
  70 #else /* !(defined(_LGPL_SOURCE) || defined(URCU_INLINE_SMALL_FUNCTIONS)) */
  71
  72 extern void *rcu_dereference_sym(void *p);
  73 #define rcu_dereference(p)                                                   \
  74         ({                                                                   \
  75                 __typeof__(p) _________p1 =     URCU_FORCE_CAST(__typeof__(p), \
  76                         rcu_dereference_sym(URCU_FORCE_CAST(void *, p)));    \
  77                 (_________p1);                                               \
  78         })
  79
  80 extern void *rcu_cmpxchg_pointer_sym(void **p, void *old, void *_new);
  81 #define rcu_cmpxchg_pointer(p, old, _new)                                    \
  82         ({                                                                   \
  83                 __typeof__(*(p)) _________pold = (old);                      \
  84                 __typeof__(*(p)) _________pnew = (_new);                     \
  85                 __typeof__(*(p)) _________p1 = URCU_FORCE_CAST(__typeof__(*(p)), \
  86                         rcu_cmpxchg_pointer_sym(URCU_FORCE_CAST(void **, p), \
  87                                                 _________pold,               \
  88                                                 _________pnew));             \
  89                 (_________p1);                                               \
  90         })
  91
  92 extern void *rcu_xchg_pointer_sym(void **p, void *v);
  93 #define rcu_xchg_pointer(p, v)                                               \
  94         ({                                                                   \
  95                 __typeof__(*(p)) _________pv = (v);                          \
  96                 __typeof__(*(p)) _________p1 = URCU_FORCE_CAST(__typeof__(*(p)), \
  97                         rcu_xchg_pointer_sym(URCU_FORCE_CAST(void **, p),    \
  98                                              _________pv));                  \
  99                 (_________p1);                                               \
 100         })
 101
 102 /*
 103  * Note: rcu_set_pointer_sym returns @v because we don't want to break
 104  * the ABI. At the API level, rcu_set_pointer() now returns void. Use of
 105  * the return value is therefore deprecated, and will cause a build
 106  * error.
 107  */
 108 extern void *rcu_set_pointer_sym(void **p, void *v);
 109 #define rcu_set_pointer(p, v)                                                \
 110         do {                                                                 \
 111                 __typeof__(*(p)) _________pv = (v);                          \
 112                 (void) rcu_set_pointer_sym(URCU_FORCE_CAST(void **, p),      \
 113                                             _________pv);                    \
 114         } while (0)
 115
 116 #endif /* !(defined(_LGPL_SOURCE) || defined(URCU_INLINE_SMALL_FUNCTIONS)) */
 117
 118 /*
 119  * void rcu_assign_pointer(type *ptr, type *new)
 120  *
 121  * Same as rcu_set_pointer, but takes the pointer to assign to rather than its
 122  * address as first parameter. Provided for compatibility with the Linux kernel
 123  * RCU semantic.
 124  */
 125 #define rcu_assign_pointer(p, v)        rcu_set_pointer((&p), (v))
 126
 127 #ifdef __cplusplus
 128 }
 129 #endif
 130
 131 #endif /* _URCU_POINTER_H */