urcu/tls-compat.h

   1 #ifndef _URCU_TLS_COMPAT_H
   2 #define _URCU_TLS_COMPAT_H
   3
   4 /*
   5  * urcu/tls-compat.h
   6  *
   7  * Userspace RCU library - Thread-Local Storage Compatibility Header
   8  *
   9  * Copyright 2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  *
  11  * This library is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU Lesser General Public
  13  * License as published by the Free Software Foundation; either
  14  * version 2.1 of the License, or (at your option) any later version.
  15  *
  16  * This library is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19  * Lesser General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public
  22  * License along with this library; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  24  */
  25
  26 #include <stdlib.h>
  27 #include <urcu/config.h>
  28 #include <urcu/compiler.h>
  29 #include <urcu/arch.h>
  30
  31 #ifdef __cplusplus
  32 extern "C" {
  33 #endif
  34
  35 #ifdef CONFIG_RCU_TLS   /* Based on ax_tls.m4 */
  36
  37 # define DECLARE_URCU_TLS(type, name)   \
  38         CONFIG_RCU_TLS type name
  39
  40 # define DEFINE_URCU_TLS(type, name)    \
  41         CONFIG_RCU_TLS type name
  42
  43 # define URCU_TLS(name)         (name)
  44
  45 #else /* #ifndef CONFIG_RCU_TLS */
  46
  47 # include <pthread.h>
  48
  49 struct urcu_tls {
  50         pthread_key_t key;
  51         pthread_mutex_t init_mutex;
  52         int init_done;
  53 };
  54
  55 # define DECLARE_URCU_TLS(type, name)                           \
  56         type *__tls_access_ ## name(void)
  57
  58 /*
  59  * Note: we don't free memory at process exit, since it will be dealt
  60  * with by the OS.
  61  */
  62 # define DEFINE_URCU_TLS(type, name)                            \
  63         type *__tls_access_ ## name(void)                       \
  64         {                                                       \
  65                 static struct urcu_tls __tls_ ## name = {       \
  66                         .init_mutex = PTHREAD_MUTEX_INITIALIZER,\
  67                         .init_done = 0,                         \
  68                 };                                              \
  69                 void *__tls_p;                                  \
  70                 if (!__tls_ ## name.init_done) {                \
  71                         /* Mutex to protect concurrent init */  \
  72                         pthread_mutex_lock(&__tls_ ## name.init_mutex); \
  73                         if (!__tls_ ## name.init_done) {        \
  74                                 (void) pthread_key_create(&__tls_ ## name.key, \
  75                                         free);                  \
  76                                 cmm_smp_wmb();  /* create key before write init_done */ \
  77                                 __tls_ ## name.init_done = 1;   \
  78                         }                                       \
  79                         pthread_mutex_unlock(&__tls_ ## name.init_mutex); \
  80                 }                                               \
  81                 cmm_smp_rmb();  /* read init_done before getting key */ \
  82                 __tls_p = pthread_getspecific(__tls_ ## name.key); \
  83                 if (caa_unlikely(__tls_p == NULL)) {            \
  84                         __tls_p = calloc(1, sizeof(type));      \
  85                         (void) pthread_setspecific(__tls_ ## name.key,  \
  86                                 __tls_p);                       \
  87                 }                                               \
  88                 return __tls_p;                                 \
  89         }
  90
  91 # define URCU_TLS(name)         (*__tls_access_ ## name())
  92
  93 #endif  /* #else #ifndef CONFIG_RCU_TLS */
  94
  95 #ifdef __cplusplus
  96 }
  97 #endif
  98
  99 #endif /* _URCU_TLS_COMPAT_H */