linux/include/linux/ring_buffer.h
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   1#ifndef _LINUX_RING_BUFFER_H
   2#define _LINUX_RING_BUFFER_H
   3
   4#include <linux/kmemcheck.h>
   5#include <linux/mm.h>
   6#include <linux/seq_file.h>
   7
   8struct ring_buffer;
   9struct ring_buffer_iter;
  10
  11/*
  12 * Don't refer to this struct directly, use functions below.
  13 */
  14struct ring_buffer_event {
  15        kmemcheck_bitfield_begin(bitfield);
  16        u32             type_len:5, time_delta:27;
  17        kmemcheck_bitfield_end(bitfield);
  18
  19        u32             array[];
  20};
  21
  22/**
  23 * enum ring_buffer_type - internal ring buffer types
  24 *
  25 * @RINGBUF_TYPE_PADDING:       Left over page padding or discarded event
  26 *                               If time_delta is 0:
  27 *                                array is ignored
  28 *                                size is variable depending on how much
  29 *                                padding is needed
  30 *                               If time_delta is non zero:
  31 *                                array[0] holds the actual length
  32 *                                size = 4 + length (bytes)
  33 *
  34 * @RINGBUF_TYPE_TIME_EXTEND:   Extend the time delta
  35 *                               array[0] = time delta (28 .. 59)
  36 *                               size = 8 bytes
  37 *
  38 * @RINGBUF_TYPE_TIME_STAMP:    Sync time stamp with external clock
  39 *                               array[0]    = tv_nsec
  40 *                               array[1..2] = tv_sec
  41 *                               size = 16 bytes
  42 *
  43 * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
  44 *                              Data record
  45 *                               If type_len is zero:
  46 *                                array[0] holds the actual length
  47 *                                array[1..(length+3)/4] holds data
  48 *                                size = 4 + length (bytes)
  49 *                               else
  50 *                                length = type_len << 2
  51 *                                array[0..(length+3)/4-1] holds data
  52 *                                size = 4 + length (bytes)
  53 */
  54enum ring_buffer_type {
  55        RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
  56        RINGBUF_TYPE_PADDING,
  57        RINGBUF_TYPE_TIME_EXTEND,
  58        /* FIXME: RINGBUF_TYPE_TIME_STAMP not implemented */
  59        RINGBUF_TYPE_TIME_STAMP,
  60};
  61
  62unsigned ring_buffer_event_length(struct ring_buffer_event *event);
  63void *ring_buffer_event_data(struct ring_buffer_event *event);
  64
  65/*
  66 * ring_buffer_discard_commit will remove an event that has not
  67 *   ben committed yet. If this is used, then ring_buffer_unlock_commit
  68 *   must not be called on the discarded event. This function
  69 *   will try to remove the event from the ring buffer completely
  70 *   if another event has not been written after it.
  71 *
  72 * Example use:
  73 *
  74 *  if (some_condition)
  75 *    ring_buffer_discard_commit(buffer, event);
  76 *  else
  77 *    ring_buffer_unlock_commit(buffer, event);
  78 */
  79void ring_buffer_discard_commit(struct ring_buffer *buffer,
  80                                struct ring_buffer_event *event);
  81
  82/*
  83 * size is in bytes for each per CPU buffer.
  84 */
  85struct ring_buffer *
  86__ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
  87
  88/*
  89 * Because the ring buffer is generic, if other users of the ring buffer get
  90 * traced by ftrace, it can produce lockdep warnings. We need to keep each
  91 * ring buffer's lock class separate.
  92 */
  93#define ring_buffer_alloc(size, flags)                  \
  94({                                                      \
  95        static struct lock_class_key __key;             \
  96        __ring_buffer_alloc((size), (flags), &__key);   \
  97})
  98
  99#define RING_BUFFER_ALL_CPUS -1
 100
 101void ring_buffer_free(struct ring_buffer *buffer);
 102
 103int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, int cpu);
 104
 105void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val);
 106
 107struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer,
 108                                                   unsigned long length);
 109int ring_buffer_unlock_commit(struct ring_buffer *buffer,
 110                              struct ring_buffer_event *event);
 111int ring_buffer_write(struct ring_buffer *buffer,
 112                      unsigned long length, void *data);
 113
 114struct ring_buffer_event *
 115ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts,
 116                 unsigned long *lost_events);
 117struct ring_buffer_event *
 118ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts,
 119                    unsigned long *lost_events);
 120
 121struct ring_buffer_iter *
 122ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu);
 123void ring_buffer_read_prepare_sync(void);
 124void ring_buffer_read_start(struct ring_buffer_iter *iter);
 125void ring_buffer_read_finish(struct ring_buffer_iter *iter);
 126
 127struct ring_buffer_event *
 128ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
 129struct ring_buffer_event *
 130ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
 131void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
 132int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
 133
 134unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu);
 135
 136void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
 137void ring_buffer_reset(struct ring_buffer *buffer);
 138
 139#ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
 140int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 141                         struct ring_buffer *buffer_b, int cpu);
 142#else
 143static inline int
 144ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 145                     struct ring_buffer *buffer_b, int cpu)
 146{
 147        return -ENODEV;
 148}
 149#endif
 150
 151int ring_buffer_empty(struct ring_buffer *buffer);
 152int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);
 153
 154void ring_buffer_record_disable(struct ring_buffer *buffer);
 155void ring_buffer_record_enable(struct ring_buffer *buffer);
 156void ring_buffer_record_off(struct ring_buffer *buffer);
 157void ring_buffer_record_on(struct ring_buffer *buffer);
 158int ring_buffer_record_is_on(struct ring_buffer *buffer);
 159void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
 160void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);
 161
 162u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu);
 163unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu);
 164unsigned long ring_buffer_entries(struct ring_buffer *buffer);
 165unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
 166unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
 167unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
 168unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);
 169unsigned long ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu);
 170unsigned long ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu);
 171
 172u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
 173void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
 174                                      int cpu, u64 *ts);
 175void ring_buffer_set_clock(struct ring_buffer *buffer,
 176                           u64 (*clock)(void));
 177
 178size_t ring_buffer_page_len(void *page);
 179
 180
 181void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu);
 182void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data);
 183int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
 184                          size_t len, int cpu, int full);
 185
 186struct trace_seq;
 187
 188int ring_buffer_print_entry_header(struct trace_seq *s);
 189int ring_buffer_print_page_header(struct trace_seq *s);
 190
 191enum ring_buffer_flags {
 192        RB_FL_OVERWRITE         = 1 << 0,
 193};
 194
 195#endif /* _LINUX_RING_BUFFER_H */
 196
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