| 1 | #ifndef _LINUX_RING_BUFFER_FRONTEND_TYPES_H |
| 2 | #define _LINUX_RING_BUFFER_FRONTEND_TYPES_H |
| 3 | |
| 4 | /* |
| 5 | * linux/ringbuffer/frontend_types.h |
| 6 | * |
| 7 | * (C) Copyright 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 8 | * |
| 9 | * Ring Buffer Library Synchronization Header (types). |
| 10 | * |
| 11 | * Author: |
| 12 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 13 | * |
| 14 | * See ring_buffer_frontend.c for more information on wait-free algorithms. |
| 15 | * |
| 16 | * Dual LGPL v2.1/GPL v2 license. |
| 17 | */ |
| 18 | |
| 19 | #include <string.h> |
| 20 | |
| 21 | #include <urcu/list.h> |
| 22 | #include <urcu/uatomic.h> |
| 23 | |
| 24 | #include <lttng/ringbuffer-config.h> |
| 25 | #include <usterr-signal-safe.h> |
| 26 | #include "backend_types.h" |
| 27 | #include "shm_internal.h" |
| 28 | #include "vatomic.h" |
| 29 | |
| 30 | /* |
| 31 | * A switch is done during tracing or as a final flush after tracing (so it |
| 32 | * won't write in the new sub-buffer). |
| 33 | */ |
| 34 | enum switch_mode { SWITCH_ACTIVE, SWITCH_FLUSH }; |
| 35 | |
| 36 | /* channel: collection of per-cpu ring buffers. */ |
| 37 | struct channel { |
| 38 | int record_disabled; |
| 39 | unsigned long commit_count_mask; /* |
| 40 | * Commit count mask, removing |
| 41 | * the MSBs corresponding to |
| 42 | * bits used to represent the |
| 43 | * subbuffer index. |
| 44 | */ |
| 45 | |
| 46 | unsigned long switch_timer_interval; /* Buffer flush (jiffies) */ |
| 47 | unsigned long read_timer_interval; /* Reader wakeup (jiffies) */ |
| 48 | //wait_queue_head_t read_wait; /* reader wait queue */ |
| 49 | int finalized; /* Has channel been finalized */ |
| 50 | size_t priv_data_offset; |
| 51 | /* |
| 52 | * Associated backend contains a variable-length array. Needs to |
| 53 | * be last member. |
| 54 | */ |
| 55 | struct channel_backend backend; /* Associated backend */ |
| 56 | } __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
| 57 | |
| 58 | /* Per-subbuffer commit counters used on the hot path */ |
| 59 | struct commit_counters_hot { |
| 60 | union v_atomic cc; /* Commit counter */ |
| 61 | union v_atomic seq; /* Consecutive commits */ |
| 62 | } __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
| 63 | |
| 64 | /* Per-subbuffer commit counters used only on cold paths */ |
| 65 | struct commit_counters_cold { |
| 66 | union v_atomic cc_sb; /* Incremented _once_ at sb switch */ |
| 67 | } __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
| 68 | |
| 69 | /* ring buffer state */ |
| 70 | struct lttng_ust_lib_ring_buffer { |
| 71 | /* First 32 bytes cache-hot cacheline */ |
| 72 | union v_atomic offset; /* Current offset in the buffer */ |
| 73 | DECLARE_SHMP(struct commit_counters_hot, commit_hot); |
| 74 | /* Commit count per sub-buffer */ |
| 75 | long consumed; /* |
| 76 | * Current offset in the buffer |
| 77 | * standard atomic access (shared) |
| 78 | */ |
| 79 | int record_disabled; |
| 80 | /* End of first 32 bytes cacheline */ |
| 81 | union v_atomic last_tsc; /* |
| 82 | * Last timestamp written in the buffer. |
| 83 | */ |
| 84 | |
| 85 | struct lttng_ust_lib_ring_buffer_backend backend; /* Associated backend */ |
| 86 | |
| 87 | DECLARE_SHMP(struct commit_counters_cold, commit_cold); |
| 88 | /* Commit count per sub-buffer */ |
| 89 | long active_readers; /* |
| 90 | * Active readers count |
| 91 | * standard atomic access (shared) |
| 92 | */ |
| 93 | long active_shadow_readers; |
| 94 | /* Dropped records */ |
| 95 | union v_atomic records_lost_full; /* Buffer full */ |
| 96 | union v_atomic records_lost_wrap; /* Nested wrap-around */ |
| 97 | union v_atomic records_lost_big; /* Events too big */ |
| 98 | union v_atomic records_count; /* Number of records written */ |
| 99 | union v_atomic records_overrun; /* Number of overwritten records */ |
| 100 | //wait_queue_head_t read_wait; /* reader buffer-level wait queue */ |
| 101 | int finalized; /* buffer has been finalized */ |
| 102 | //struct timer_list switch_timer; /* timer for periodical switch */ |
| 103 | //struct timer_list read_timer; /* timer for read poll */ |
| 104 | unsigned long get_subbuf_consumed; /* Read-side consumed */ |
| 105 | unsigned long prod_snapshot; /* Producer count snapshot */ |
| 106 | unsigned long cons_snapshot; /* Consumer count snapshot */ |
| 107 | unsigned int get_subbuf:1, /* Sub-buffer being held by reader */ |
| 108 | switch_timer_enabled:1, /* Protected by ring_buffer_nohz_lock */ |
| 109 | read_timer_enabled:1; /* Protected by ring_buffer_nohz_lock */ |
| 110 | /* shmp pointer to self */ |
| 111 | DECLARE_SHMP(struct lttng_ust_lib_ring_buffer, self); |
| 112 | } __attribute__((aligned(CAA_CACHE_LINE_SIZE))); |
| 113 | |
| 114 | static inline |
| 115 | void *channel_get_private(struct channel *chan) |
| 116 | { |
| 117 | return ((char *) chan) + chan->priv_data_offset; |
| 118 | } |
| 119 | |
| 120 | #ifndef __rb_same_type |
| 121 | #define __rb_same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b)) |
| 122 | #endif |
| 123 | |
| 124 | /* |
| 125 | * Issue warnings and disable channels upon internal error. |
| 126 | * Can receive struct lttng_ust_lib_ring_buffer or struct lttng_ust_lib_ring_buffer_backend |
| 127 | * parameters. |
| 128 | */ |
| 129 | #define CHAN_WARN_ON(c, cond) \ |
| 130 | ({ \ |
| 131 | struct channel *__chan; \ |
| 132 | int _____ret = caa_unlikely(cond); \ |
| 133 | if (_____ret) { \ |
| 134 | if (__rb_same_type(*(c), struct channel_backend)) \ |
| 135 | __chan = caa_container_of((void *) (c), \ |
| 136 | struct channel, \ |
| 137 | backend); \ |
| 138 | else if (__rb_same_type(*(c), struct channel)) \ |
| 139 | __chan = (void *) (c); \ |
| 140 | else \ |
| 141 | BUG_ON(1); \ |
| 142 | uatomic_inc(&__chan->record_disabled); \ |
| 143 | WARN_ON(1); \ |
| 144 | } \ |
| 145 | _____ret; \ |
| 146 | }) |
| 147 | |
| 148 | #endif /* _LINUX_RING_BUFFER_FRONTEND_TYPES_H */ |