urcu-qsbr.h

   1 #ifndef _URCU_QSBR_H
   2 #define _URCU_QSBR_H
   3
   4 /*
   5  * urcu-qsbr.h
   6  *
   7  * Userspace RCU QSBR header.
   8  *
   9  * LGPL-compatible code should include this header with :
  10  *
  11  * #define _LGPL_SOURCE
  12  * #include <urcu.h>
  13  *
  14  * This library is free software; you can redistribute it and/or
  15  * modify it under the terms of the GNU Lesser General Public
  16  * License as published by the Free Software Foundation; either
  17  * version 2.1 of the License, or (at your option) any later version.
  18  *
  19  * This library is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  22  * Lesser General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Lesser General Public
  25  * License along with this library; if not, write to the Free Software
  26  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  27  *
  28  * IBM's contributions to this file may be relicensed under LGPLv2 or later.
  29  */
  30
  31 #include <stdlib.h>
  32 #include <pthread.h>
  33
  34 /*
  35  * Important !
  36  *
  37  * Each thread containing read-side critical sections must be registered
  38  * with rcu_register_thread() before calling rcu_read_lock().
  39  * rcu_unregister_thread() should be called before the thread exits.
  40  */
  41
  42 #ifdef _LGPL_SOURCE
  43
  44 #include <urcu-qsbr-static.h>
  45
  46 /*
  47  * Mappings for static use of the userspace RCU library.
  48  * Should only be used in LGPL-compatible code.
  49  */
  50
  51 #define rcu_dereference         _rcu_dereference
  52 #define rcu_read_lock           _rcu_read_lock
  53 #define rcu_read_unlock         _rcu_read_unlock
  54
  55 #define rcu_quiescent_state     _rcu_quiescent_state
  56 #define rcu_thread_offline      _rcu_thread_offline
  57 #define rcu_thread_online       _rcu_thread_online
  58
  59 #define rcu_assign_pointer      _rcu_assign_pointer
  60 #define rcu_cmpxchg_pointer     _rcu_cmpxchg_pointer
  61 #define rcu_xchg_pointer        _rcu_xchg_pointer
  62 #define rcu_publish_content     _rcu_publish_content
  63
  64 #else /* !_LGPL_SOURCE */
  65
  66 /*
  67  * library wrappers to be used by non-LGPL compatible source code.
  68  */
  69
  70 /*
  71  * QSBR read lock/unlock are guaranteed to be no-ops. Therefore, we expose them
  72  * in the LGPL header for any code to use. However, the debug version is not
  73  * nops and may contain sanity checks. To activate it, applications must be
  74  * recompiled with -DURCU_DEBUG (even non-LGPL/GPL applications). This is the
  75  * best trade-off between license/performance/code triviality and
  76  * library debugging & tracing features we could come up with.
  77  */
  78
  79 #if (!defined(BUILD_QSBR_LIB) && defined(URCU_DEBUG))
  80
  81 static inline void rcu_read_lock(void)
  82 {
  83 }
  84
  85 static inline void rcu_read_lock(void)
  86 {
  87 }
  88
  89 #else /* !URCU_DEBUG */
  90
  91 extern void rcu_read_lock(void);
  92 extern void rcu_read_unlock(void);
  93
  94 #endif /* !URCU_DEBUG */
  95
  96 extern void *rcu_dereference(void *p);
  97
  98 extern void rcu_quiescent_state(void);
  99 extern void rcu_thread_offline(void);
 100 extern void rcu_thread_online(void);
 101
 102 extern void *rcu_assign_pointer_sym(void **p, void *v);
 103
 104 #define rcu_assign_pointer(p, v)                        \
 105         rcu_assign_pointer_sym((void **)(p), (v))
 106
 107 extern void *rcu_cmpxchg_pointer_sym(void **p, void *old, void *_new);
 108 #define rcu_cmpxchg_pointer(p, old, _new)               \
 109         rcu_cmpxchg_pointer_sym((void **)(p), (old), (_new))
 110
 111 extern void *rcu_xchg_pointer_sym(void **p, void *v);
 112 #define rcu_xchg_pointer(p, v)                          \
 113         rcu_xchg_pointer_sym((void **)(p), (v))
 114
 115 extern void *rcu_publish_content_sym(void **p, void *v);
 116 #define rcu_publish_content(p, v)                       \
 117         rcu_publish_content_sym((void **)(p), (v))
 118
 119 #endif /* !_LGPL_SOURCE */
 120
 121 extern void synchronize_rcu(void);
 122
 123 /*
 124  * Reader thread registration.
 125  */
 126 extern void rcu_register_thread(void);
 127 extern void rcu_unregister_thread(void);
 128
 129 #endif /* _URCU_QSBR_H */