| 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 "config.h" |
| 20 | #include "backend_types.h" |
| 21 | #include "../lib_prio_heap/lttng_prio_heap.h" /* For per-CPU read-side iterator */ |
| 22 | |
| 23 | /* |
| 24 | * A switch is done during tracing or as a final flush after tracing (so it |
| 25 | * won't write in the new sub-buffer). |
| 26 | */ |
| 27 | enum switch_mode { SWITCH_ACTIVE, SWITCH_FLUSH }; |
| 28 | |
| 29 | /* channel-level read-side iterator */ |
| 30 | struct channel_iter { |
| 31 | /* Prio heap of buffers. Lowest timestamps at the top. */ |
| 32 | struct lttng_ptr_heap heap; /* Heap of struct lib_ring_buffer ptrs */ |
| 33 | struct list_head empty_head; /* Empty buffers linked-list head */ |
| 34 | int read_open; /* Opened for reading ? */ |
| 35 | u64 last_qs; /* Last quiescent state timestamp */ |
| 36 | u64 last_timestamp; /* Last timestamp (for WARN_ON) */ |
| 37 | int last_cpu; /* Last timestamp cpu */ |
| 38 | /* |
| 39 | * read() file operation state. |
| 40 | */ |
| 41 | unsigned long len_left; |
| 42 | }; |
| 43 | |
| 44 | /* channel: collection of per-cpu ring buffers. */ |
| 45 | struct channel { |
| 46 | atomic_t record_disabled; |
| 47 | unsigned long commit_count_mask; /* |
| 48 | * Commit count mask, removing |
| 49 | * the MSBs corresponding to |
| 50 | * bits used to represent the |
| 51 | * subbuffer index. |
| 52 | */ |
| 53 | |
| 54 | struct channel_backend backend; /* Associated backend */ |
| 55 | |
| 56 | unsigned long switch_timer_interval; /* Buffer flush (jiffies) */ |
| 57 | unsigned long read_timer_interval; /* Reader wakeup (jiffies) */ |
| 58 | struct notifier_block cpu_hp_notifier; /* CPU hotplug notifier */ |
| 59 | struct notifier_block tick_nohz_notifier; /* CPU nohz notifier */ |
| 60 | struct notifier_block hp_iter_notifier; /* hotplug iterator notifier */ |
| 61 | int cpu_hp_enable:1; /* Enable CPU hotplug notif. */ |
| 62 | int hp_iter_enable:1; /* Enable hp iter notif. */ |
| 63 | wait_queue_head_t read_wait; /* reader wait queue */ |
| 64 | wait_queue_head_t hp_wait; /* CPU hotplug wait queue */ |
| 65 | int finalized; /* Has channel been finalized */ |
| 66 | struct channel_iter iter; /* Channel read-side iterator */ |
| 67 | struct kref ref; /* Reference count */ |
| 68 | }; |
| 69 | |
| 70 | /* Per-subbuffer commit counters used on the hot path */ |
| 71 | struct commit_counters_hot { |
| 72 | union v_atomic cc; /* Commit counter */ |
| 73 | union v_atomic seq; /* Consecutive commits */ |
| 74 | }; |
| 75 | |
| 76 | /* Per-subbuffer commit counters used only on cold paths */ |
| 77 | struct commit_counters_cold { |
| 78 | union v_atomic cc_sb; /* Incremented _once_ at sb switch */ |
| 79 | }; |
| 80 | |
| 81 | /* Per-buffer read iterator */ |
| 82 | struct lib_ring_buffer_iter { |
| 83 | u64 timestamp; /* Current record timestamp */ |
| 84 | size_t header_len; /* Current record header length */ |
| 85 | size_t payload_len; /* Current record payload length */ |
| 86 | |
| 87 | struct list_head empty_node; /* Linked list of empty buffers */ |
| 88 | unsigned long consumed, read_offset, data_size; |
| 89 | enum { |
| 90 | ITER_GET_SUBBUF = 0, |
| 91 | ITER_TEST_RECORD, |
| 92 | ITER_NEXT_RECORD, |
| 93 | ITER_PUT_SUBBUF, |
| 94 | } state; |
| 95 | int allocated:1; |
| 96 | int read_open:1; /* Opened for reading ? */ |
| 97 | }; |
| 98 | |
| 99 | /* ring buffer state */ |
| 100 | struct lib_ring_buffer { |
| 101 | /* First 32 bytes cache-hot cacheline */ |
| 102 | union v_atomic offset; /* Current offset in the buffer */ |
| 103 | struct commit_counters_hot *commit_hot; |
| 104 | /* Commit count per sub-buffer */ |
| 105 | atomic_long_t consumed; /* |
| 106 | * Current offset in the buffer |
| 107 | * standard atomic access (shared) |
| 108 | */ |
| 109 | atomic_t record_disabled; |
| 110 | /* End of first 32 bytes cacheline */ |
| 111 | union v_atomic last_tsc; /* |
| 112 | * Last timestamp written in the buffer. |
| 113 | */ |
| 114 | |
| 115 | struct lib_ring_buffer_backend backend; /* Associated backend */ |
| 116 | |
| 117 | struct commit_counters_cold *commit_cold; |
| 118 | /* Commit count per sub-buffer */ |
| 119 | atomic_long_t active_readers; /* |
| 120 | * Active readers count |
| 121 | * standard atomic access (shared) |
| 122 | */ |
| 123 | /* Dropped records */ |
| 124 | union v_atomic records_lost_full; /* Buffer full */ |
| 125 | union v_atomic records_lost_wrap; /* Nested wrap-around */ |
| 126 | union v_atomic records_lost_big; /* Events too big */ |
| 127 | union v_atomic records_count; /* Number of records written */ |
| 128 | union v_atomic records_overrun; /* Number of overwritten records */ |
| 129 | wait_queue_head_t read_wait; /* reader buffer-level wait queue */ |
| 130 | int finalized; /* buffer has been finalized */ |
| 131 | struct timer_list switch_timer; /* timer for periodical switch */ |
| 132 | struct timer_list read_timer; /* timer for read poll */ |
| 133 | raw_spinlock_t raw_tick_nohz_spinlock; /* nohz entry lock/trylock */ |
| 134 | struct lib_ring_buffer_iter iter; /* read-side iterator */ |
| 135 | unsigned long get_subbuf_consumed; /* Read-side consumed */ |
| 136 | unsigned long prod_snapshot; /* Producer count snapshot */ |
| 137 | unsigned long cons_snapshot; /* Consumer count snapshot */ |
| 138 | int get_subbuf:1; /* Sub-buffer being held by reader */ |
| 139 | int switch_timer_enabled:1; /* Protected by ring_buffer_nohz_lock */ |
| 140 | int read_timer_enabled:1; /* Protected by ring_buffer_nohz_lock */ |
| 141 | }; |
| 142 | |
| 143 | static inline |
| 144 | void *channel_get_private(struct channel *chan) |
| 145 | { |
| 146 | return chan->backend.priv; |
| 147 | } |
| 148 | |
| 149 | /* |
| 150 | * Issue warnings and disable channels upon internal error. |
| 151 | * Can receive struct lib_ring_buffer or struct lib_ring_buffer_backend |
| 152 | * parameters. |
| 153 | */ |
| 154 | #define CHAN_WARN_ON(c, cond) \ |
| 155 | ({ \ |
| 156 | struct channel *__chan; \ |
| 157 | int _____ret = unlikely(cond); \ |
| 158 | if (_____ret) { \ |
| 159 | if (__same_type(*(c), struct channel_backend)) \ |
| 160 | __chan = container_of((void *) (c), \ |
| 161 | struct channel, \ |
| 162 | backend); \ |
| 163 | else if (__same_type(*(c), struct channel)) \ |
| 164 | __chan = (void *) (c); \ |
| 165 | else \ |
| 166 | BUG_ON(1); \ |
| 167 | atomic_inc(&__chan->record_disabled); \ |
| 168 | WARN_ON(1); \ |
| 169 | } \ |
| 170 | _____ret; \ |
| 171 | }) |
| 172 | |
| 173 | #endif /* _LINUX_RING_BUFFER_FRONTEND_TYPES_H */ |