| 1 | #ifndef _LTTNG_RING_BUFFER_VATOMIC_H |
| 2 | #define _LTTNG_RING_BUFFER_VATOMIC_H |
| 3 | |
| 4 | /* |
| 5 | * libringbuffer/vatomic.h |
| 6 | * |
| 7 | * Copyright (C) 2010-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 8 | * |
| 9 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
| 10 | * of this software and associated documentation files (the "Software"), to deal |
| 11 | * in the Software without restriction, including without limitation the rights |
| 12 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| 13 | * copies of the Software, and to permit persons to whom the Software is |
| 14 | * furnished to do so, subject to the following conditions: |
| 15 | * |
| 16 | * The above copyright notice and this permission notice shall be included in |
| 17 | * all copies or substantial portions of the Software. |
| 18 | * |
| 19 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 20 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 21 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| 22 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 23 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| 24 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
| 25 | * SOFTWARE. |
| 26 | */ |
| 27 | |
| 28 | #include <assert.h> |
| 29 | #include <urcu/uatomic.h> |
| 30 | |
| 31 | /* |
| 32 | * Same data type (long) accessed differently depending on configuration. |
| 33 | * v field is for non-atomic access (protected by mutual exclusion). |
| 34 | * In the fast-path, the ring_buffer_config structure is constant, so the |
| 35 | * compiler can statically select the appropriate branch. |
| 36 | * local_t is used for per-cpu and per-thread buffers. |
| 37 | * atomic_long_t is used for globally shared buffers. |
| 38 | */ |
| 39 | union v_atomic { |
| 40 | long a; /* accessed through uatomic */ |
| 41 | long v; |
| 42 | }; |
| 43 | |
| 44 | static inline |
| 45 | long v_read(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a) |
| 46 | { |
| 47 | assert(config->sync != RING_BUFFER_SYNC_PER_CPU); |
| 48 | return uatomic_read(&v_a->a); |
| 49 | } |
| 50 | |
| 51 | static inline |
| 52 | void v_set(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a, |
| 53 | long v) |
| 54 | { |
| 55 | assert(config->sync != RING_BUFFER_SYNC_PER_CPU); |
| 56 | uatomic_set(&v_a->a, v); |
| 57 | } |
| 58 | |
| 59 | static inline |
| 60 | void v_add(const struct lttng_ust_lib_ring_buffer_config *config, long v, union v_atomic *v_a) |
| 61 | { |
| 62 | assert(config->sync != RING_BUFFER_SYNC_PER_CPU); |
| 63 | uatomic_add(&v_a->a, v); |
| 64 | } |
| 65 | |
| 66 | static inline |
| 67 | void v_inc(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a) |
| 68 | { |
| 69 | assert(config->sync != RING_BUFFER_SYNC_PER_CPU); |
| 70 | uatomic_inc(&v_a->a); |
| 71 | } |
| 72 | |
| 73 | /* |
| 74 | * Non-atomic decrement. Only used by reader, apply to reader-owned subbuffer. |
| 75 | */ |
| 76 | static inline |
| 77 | void _v_dec(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a) |
| 78 | { |
| 79 | --v_a->v; |
| 80 | } |
| 81 | |
| 82 | static inline |
| 83 | long v_cmpxchg(const struct lttng_ust_lib_ring_buffer_config *config, union v_atomic *v_a, |
| 84 | long old, long _new) |
| 85 | { |
| 86 | assert(config->sync != RING_BUFFER_SYNC_PER_CPU); |
| 87 | return uatomic_cmpxchg(&v_a->a, old, _new); |
| 88 | } |
| 89 | |
| 90 | #endif /* _LTTNG_RING_BUFFER_VATOMIC_H */ |