projects / thirdparty / strongswan.git / blame
| Commit | Line | Data |
|---|---|---|
| 717313c5 MW |
1 | /* |
| 2 | * Copyright (C) 2008-2014 Tobias Brunner | |
| 3 | * Copyright (C) 2008 Martin Willi | |
| 1b671669 | 4 | * HSR Hochschule fuer Technik Rapperswil |
| 717313c5 MW |
5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify it | |
| 7 | * under the terms of the GNU General Public License as published by the | |
| 8 | * Free Software Foundation; either version 2 of the License, or (at your | |
| 9 | * option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>. | |
| 10 | * | |
| 11 | * This program is distributed in the hope that it will be useful, but | |
| 12 | * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY | |
| 13 | * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | * for more details. | |
| 15 | */ | |
| 16 | ||
| 17 | /** | |
| 18 | * @defgroup atomics_i atomics | |
| 19 | * @{ @ingroup utils_i | |
| 20 | */ | |
| 21 | ||
| 22 | #ifndef ATOMICS_H_ | |
| 23 | #define ATOMICS_H_ | |
| 24 | ||
| 25 | /** | |
| 26 | * Special type to count references | |
| 27 | */ | |
| 28 | typedef u_int refcount_t; | |
| 29 | ||
| 942599b6 TB |
30 | /* use __atomic* built-ins with clang, if available (note that clang also |
| 31 | * defines __GNUC__, however only claims to be GCC 4.2) */ | |
| 32 | #if defined(__clang__) | |
| 33 | # if __has_builtin(__atomic_add_fetch) | |
| 34 | # define HAVE_GCC_ATOMIC_OPERATIONS | |
| 35 | # endif | |
| 717313c5 | 36 | /* use __atomic* built-ins with GCC 4.7 and newer */ |
| 942599b6 | 37 | #elif defined(__GNUC__) |
| 717313c5 MW |
38 | # if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ > 6)) |
| 39 | # define HAVE_GCC_ATOMIC_OPERATIONS | |
| 40 | # endif | |
| 41 | #endif | |
| 42 | ||
| 43 | #ifdef HAVE_GCC_ATOMIC_OPERATIONS | |
| 44 | ||
| 45 | #define ref_get(ref) __atomic_add_fetch(ref, 1, __ATOMIC_RELAXED) | |
| 46 | /* The relaxed memory model works fine for increments as these (usually) don't | |
| 47 | * change the state of refcounted objects. But here we have to ensure that we | |
| 48 | * free the right stuff if ref counted objects are mutable. So we have to sync | |
| 49 | * with other threads that call ref_put(). It would be sufficient to use | |
| 50 | * __ATOMIC_RELEASE here and then call __atomic_thread_fence() with | |
| 51 | * __ATOMIC_ACQUIRE if we reach 0, but since we don't have control over the use | |
| 52 | * of ref_put() we have to make sure. */ | |
| 53 | #define ref_put(ref) (!__atomic_sub_fetch(ref, 1, __ATOMIC_ACQ_REL)) | |
| 54 | #define ref_cur(ref) __atomic_load_n(ref, __ATOMIC_RELAXED) | |
| 55 | ||
| 56 | #define _cas_impl(ptr, oldval, newval) ({ typeof(oldval) _old = oldval; \ | |
| 57 | __atomic_compare_exchange_n(ptr, &_old, newval, FALSE, \ | |
| 58 | __ATOMIC_SEQ_CST, __ATOMIC_RELAXED); }) | |
| 59 | #define cas_bool(ptr, oldval, newval) _cas_impl(ptr, oldval, newval) | |
| 60 | #define cas_ptr(ptr, oldval, newval) _cas_impl(ptr, oldval, newval) | |
| 61 | ||
| 62 | #elif defined(HAVE_GCC_SYNC_OPERATIONS) | |
| 63 | ||
| 64 | #define ref_get(ref) __sync_add_and_fetch(ref, 1) | |
| 65 | #define ref_put(ref) (!__sync_sub_and_fetch(ref, 1)) | |
| 66 | #define ref_cur(ref) __sync_fetch_and_add(ref, 0) | |
| 67 | ||
| 68 | #define cas_bool(ptr, oldval, newval) \ | |
| 69 | (__sync_bool_compare_and_swap(ptr, oldval, newval)) | |
| 70 | #define cas_ptr(ptr, oldval, newval) \ | |
| 71 | (__sync_bool_compare_and_swap(ptr, oldval, newval)) | |
| 72 | ||
| 73 | #else /* !HAVE_GCC_ATOMIC_OPERATIONS && !HAVE_GCC_SYNC_OPERATIONS */ | |
| 74 | ||
| 75 | /** | |
| 76 | * Get a new reference. | |
| 77 | * | |
| 78 | * Increments the reference counter atomically. | |
| 79 | * | |
| 80 | * @param ref pointer to ref counter | |
| 81 | * @return new value of ref | |
| 82 | */ | |
| 83 | refcount_t ref_get(refcount_t *ref); | |
| 84 | ||
| 85 | /** | |
| 86 | * Put back a unused reference. | |
| 87 | * | |
| 88 | * Decrements the reference counter atomically and | |
| 89 | * says if more references available. | |
| 90 | * | |
| 91 | * @param ref pointer to ref counter | |
| 92 | * @return TRUE if no more references counted | |
| 93 | */ | |
| 94 | bool ref_put(refcount_t *ref); | |
| 95 | ||
| 96 | /** | |
| 97 | * Get the current value of the reference counter. | |
| 98 | * | |
| 99 | * @param ref pointer to ref counter | |
| 100 | * @return current value of ref | |
| 101 | */ | |
| 102 | refcount_t ref_cur(refcount_t *ref); | |
| 103 | ||
| 104 | /** | |
| 105 | * Atomically replace value of ptr with newval if it currently equals oldval. | |
| 106 | * | |
| 107 | * @param ptr pointer to variable | |
| 108 | * @param oldval old value of the variable | |
| 109 | * @param newval new value set if possible | |
| 110 | * @return TRUE if value equaled oldval and newval was written | |
| 111 | */ | |
| 112 | bool cas_bool(bool *ptr, bool oldval, bool newval); | |
| 113 | ||
| 114 | /** | |
| 115 | * Atomically replace value of ptr with newval if it currently equals oldval. | |
| 116 | * | |
| 117 | * @param ptr pointer to variable | |
| 118 | * @param oldval old value of the variable | |
| 119 | * @param newval new value set if possible | |
| 120 | * @return TRUE if value equaled oldval and newval was written | |
| 121 | */ | |
| 122 | bool cas_ptr(void **ptr, void *oldval, void *newval); | |
| 123 | ||
| 124 | #endif /* HAVE_GCC_ATOMIC_OPERATIONS */ | |
| 125 | ||
| 126 | /** | |
| 127 | * Initialize atomics utility functions | |
| 128 | */ | |
| 129 | void atomics_init(); | |
| 130 | ||
| 131 | /** | |
| 132 | * Clean up atomics utility functions | |
| 133 | */ | |
| 134 | void atomics_deinit(); | |
| 135 | ||
| 136 | #endif /** ATOMICS_H_ @} */ |