| 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. Operations on pointers. |
| 8 | */ |
| 9 | |
| 10 | #ifndef _LTTNG_UST_URCU_POINTER_H |
| 11 | #define _LTTNG_UST_URCU_POINTER_H |
| 12 | |
| 13 | #include <urcu/compiler.h> |
| 14 | #include <urcu/arch.h> |
| 15 | #include <urcu/uatomic.h> |
| 16 | |
| 17 | #ifdef __cplusplus |
| 18 | extern "C" { |
| 19 | #endif |
| 20 | |
| 21 | #if defined(_LGPL_SOURCE) || defined(LTTNG_UST_URCU_INLINE_SMALL_FUNCTIONS) |
| 22 | |
| 23 | #include <lttng/urcu/static/pointer.h> |
| 24 | |
| 25 | /* |
| 26 | * lttng_ust_rcu_dereference(ptr) |
| 27 | * |
| 28 | * Fetch a RCU-protected pointer. Typically used to copy the variable ptr to a |
| 29 | * local variable. |
| 30 | */ |
| 31 | #define lttng_ust_rcu_dereference _lttng_ust_rcu_dereference |
| 32 | |
| 33 | /* |
| 34 | * type *lttng_ust_rcu_cmpxchg_pointer(type **ptr, type *new, type *old) |
| 35 | * type *lttng_ust_rcu_xchg_pointer(type **ptr, type *new) |
| 36 | * void lttng_ust_rcu_set_pointer(type **ptr, type *new) |
| 37 | * |
| 38 | * RCU pointer updates. |
| 39 | * @ptr: address of the pointer to modify |
| 40 | * @new: new pointer value |
| 41 | * @old: old pointer value (expected) |
| 42 | * |
| 43 | * return: old pointer value |
| 44 | */ |
| 45 | #define lttng_ust_rcu_cmpxchg_pointer _lttng_ust_rcu_cmpxchg_pointer |
| 46 | #define lttng_ust_rcu_xchg_pointer _lttng_ust_rcu_xchg_pointer |
| 47 | #define lttng_ust_rcu_set_pointer _lttng_ust_rcu_set_pointer |
| 48 | |
| 49 | #else /* !(defined(_LGPL_SOURCE) || defined(LTTNG_UST_URCU_INLINE_SMALL_FUNCTIONS)) */ |
| 50 | |
| 51 | extern void *lttng_ust_rcu_dereference_sym(void *p); |
| 52 | #define lttng_ust_rcu_dereference(p) \ |
| 53 | __extension__ \ |
| 54 | ({ \ |
| 55 | __typeof__(p) _________p1 = URCU_FORCE_CAST(__typeof__(p), \ |
| 56 | lttng_ust_rcu_dereference_sym(URCU_FORCE_CAST(void *, p))); \ |
| 57 | (_________p1); \ |
| 58 | }) |
| 59 | |
| 60 | extern void *lttng_ust_rcu_cmpxchg_pointer_sym(void **p, void *old, void *_new); |
| 61 | #define lttng_ust_rcu_cmpxchg_pointer(p, old, _new) \ |
| 62 | __extension__ \ |
| 63 | ({ \ |
| 64 | __typeof__(*(p)) _________pold = (old); \ |
| 65 | __typeof__(*(p)) _________pnew = (_new); \ |
| 66 | __typeof__(*(p)) _________p1 = URCU_FORCE_CAST(__typeof__(*(p)), \ |
| 67 | lttng_ust_rcu_cmpxchg_pointer_sym(URCU_FORCE_CAST(void **, p), \ |
| 68 | _________pold, \ |
| 69 | _________pnew)); \ |
| 70 | (_________p1); \ |
| 71 | }) |
| 72 | |
| 73 | extern void *lttng_ust_rcu_xchg_pointer_sym(void **p, void *v); |
| 74 | #define lttng_ust_rcu_xchg_pointer(p, v) \ |
| 75 | __extension__ \ |
| 76 | ({ \ |
| 77 | __typeof__(*(p)) _________pv = (v); \ |
| 78 | __typeof__(*(p)) _________p1 = URCU_FORCE_CAST(__typeof__(*(p)), \ |
| 79 | lttng_ust_rcu_xchg_pointer_sym(URCU_FORCE_CAST(void **, p), \ |
| 80 | _________pv)); \ |
| 81 | (_________p1); \ |
| 82 | }) |
| 83 | |
| 84 | /* |
| 85 | * Note: lttng_ust_rcu_set_pointer_sym returns @v because we don't want to break |
| 86 | * the ABI. At the API level, lttng_ust_rcu_set_pointer() now returns void. Use of |
| 87 | * the return value is therefore deprecated, and will cause a build |
| 88 | * error. |
| 89 | */ |
| 90 | extern void *lttng_ust_rcu_set_pointer_sym(void **p, void *v); |
| 91 | #define lttng_ust_rcu_set_pointer(p, v) \ |
| 92 | do { \ |
| 93 | __typeof__(*(p)) _________pv = (v); \ |
| 94 | (void) lttng_ust_rcu_set_pointer_sym(URCU_FORCE_CAST(void **, p), \ |
| 95 | _________pv); \ |
| 96 | } while (0) |
| 97 | |
| 98 | #endif /* !(defined(_LGPL_SOURCE) || defined(LTTNG_UST_URCU_INLINE_SMALL_FUNCTIONS)) */ |
| 99 | |
| 100 | /* |
| 101 | * void lttng_ust_rcu_assign_pointer(type *ptr, type *new) |
| 102 | * |
| 103 | * Same as lttng_ust_rcu_set_pointer, but takes the pointer to assign to rather than its |
| 104 | * address as first parameter. Provided for compatibility with the Linux kernel |
| 105 | * RCU semantic. |
| 106 | */ |
| 107 | #define lttng_ust_rcu_assign_pointer(p, v) lttng_ust_rcu_set_pointer((&p), (v)) |
| 108 | |
| 109 | #ifdef __cplusplus |
| 110 | } |
| 111 | #endif |
| 112 | |
| 113 | #endif /* _LTTNG_UST_URCU_POINTER_H */ |