include/lttng/urcu/urcu-ust.h

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-or-later
   3  *
   4  * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
   6  *
   7  * Userspace RCU header for LTTng-UST. Derived from liburcu
   8  * "bulletproof" flavor.
   9  *
  10  * Slower RCU read-side adapted for tracing library. Does not require thread
  11  * registration nor unregistration. Also signal-safe.
  12  *
  13  * LGPL-compatible code should include this header with :
  14  *
  15  * #define _LGPL_SOURCE
  16  * #include <lttng/urcu-ust.h>
  17  */
  18
  19 #ifndef _LTTNG_UST_URCU_H
  20 #define _LTTNG_UST_URCU_H
  21
  22 #include <stdlib.h>
  23 #include <pthread.h>
  24
  25 #ifdef __cplusplus
  26 extern "C" {
  27 #endif
  28
  29 /*
  30  * See lttng/urcu/pointer.h and lttng/urcu/static/pointer.h for pointer
  31  * publication headers.
  32  */
  33 #include <lttng/urcu/pointer.h>
  34
  35 #ifdef _LGPL_SOURCE
  36
  37 #include <lttng/urcu/static/urcu-ust.h>
  38
  39 /*
  40  * Mappings for static use of the userspace RCU library.
  41  * Should only be used in LGPL-compatible code.
  42  */
  43
  44 /*
  45  * lttng_ust_urcu_read_lock()
  46  * lttng_ust_urcu_read_unlock()
  47  *
  48  * Mark the beginning and end of a read-side critical section.
  49  */
  50 #define lttng_ust_urcu_read_lock        _lttng_ust_urcu_read_lock
  51 #define lttng_ust_urcu_read_unlock      _lttng_ust_urcu_read_unlock
  52 #define lttng_ust_urcu_read_ongoing     _lttng_ust_urcu_read_ongoing
  53
  54 #else /* !_LGPL_SOURCE */
  55
  56 /*
  57  * library wrappers to be used by non-LGPL compatible source code.
  58  * See LGPL-only urcu/static/pointer.h for documentation.
  59  */
  60
  61 extern void lttng_ust_urcu_read_lock(void);
  62 extern void lttng_ust_urcu_read_unlock(void);
  63 extern int lttng_ust_urcu_read_ongoing(void);
  64
  65 #endif /* !_LGPL_SOURCE */
  66
  67 extern void lttng_ust_urcu_synchronize_rcu(void);
  68
  69 /*
  70  * lttng_ust_urcu_before_fork, lttng_ust_urcu_after_fork_parent and
  71  * lttng_ust_urcu_after_fork_child should be called around fork() system
  72  * calls when the child process is not expected to immediately perform
  73  * an exec(). For pthread users, see pthread_atfork(3).
  74  */
  75 extern void lttng_ust_urcu_before_fork(void);
  76 extern void lttng_ust_urcu_after_fork_parent(void);
  77 extern void lttng_ust_urcu_after_fork_child(void);
  78
  79 /*
  80  * In the UST version, thread registration is performed lazily, but it can be
  81  * forced by issuing an explicit lttng_ust_urcu_register_thread().
  82  */
  83 extern void lttng_ust_urcu_register_thread(void);
  84
  85 #ifdef __cplusplus
  86 }
  87 #endif
  88
  89 #endif /* _LTTNG_UST_URCU_H */