LXR linux/include/linux/ring

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _LINUX_RING_BUFFER_H
   3#define _LINUX_RING_BUFFER_H
   4
   5#include <linux/mm.h>
   6#include <linux/seq_file.h>
   7#include <linux/poll.h>
   8
   9struct trace_buffer;
  10struct ring_buffer_iter;
  11
  12/*
  13 * Don't refer to this struct directly, use functions below.
  14 */
  15struct ring_buffer_event {
  16        u32             type_len:5, time_delta:27;
  17
  18        u32             array[];
  19};
  20
  21/**
  22 * enum ring_buffer_type - internal ring buffer types
  23 *
  24 * @RINGBUF_TYPE_PADDING:       Left over page padding or discarded event
  25 *                               If time_delta is 0:
  26 *                                array is ignored
  27 *                                size is variable depending on how much
  28 *                                padding is needed
  29 *                               If time_delta is non zero:
  30 *                                array[0] holds the actual length
  31 *                                size = 4 + length (bytes)
  32 *
  33 * @RINGBUF_TYPE_TIME_EXTEND:   Extend the time delta
  34 *                               array[0] = time delta (28 .. 59)
  35 *                               size = 8 bytes
  36 *
  37 * @RINGBUF_TYPE_TIME_STAMP:    Absolute timestamp
  38 *                               Same format as TIME_EXTEND except that the
  39 *                               value is an absolute timestamp, not a delta
  40 *                               event.time_delta contains bottom 27 bits
  41 *                               array[0] = top (28 .. 59) bits
  42 *                               size = 8 bytes
  43 *
  44 * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
  45 *                              Data record
  46 *                               If type_len is zero:
  47 *                                array[0] holds the actual length
  48 *                                array[1..(length+3)/4] holds data
  49 *                                size = 4 + length (bytes)
  50 *                               else
  51 *                                length = type_len << 2
  52 *                                array[0..(length+3)/4-1] holds data
  53 *                                size = 4 + length (bytes)
  54 */
  55enum ring_buffer_type {
  56        RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
  57        RINGBUF_TYPE_PADDING,
  58        RINGBUF_TYPE_TIME_EXTEND,
  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);
  64u64 ring_buffer_event_time_stamp(struct trace_buffer *buffer,
  65                                 struct ring_buffer_event *event);
  66
  67/*
  68 * ring_buffer_discard_commit will remove an event that has not
  69 *   been committed yet. If this is used, then ring_buffer_unlock_commit
  70 *   must not be called on the discarded event. This function
  71 *   will try to remove the event from the ring buffer completely
  72 *   if another event has not been written after it.
  73 *
  74 * Example use:
  75 *
  76 *  if (some_condition)
  77 *    ring_buffer_discard_commit(buffer, event);
  78 *  else
  79 *    ring_buffer_unlock_commit(buffer, event);
  80 */
  81void ring_buffer_discard_commit(struct trace_buffer *buffer,
  82                                struct ring_buffer_event *event);
  83
  84/*
  85 * size is in bytes for each per CPU buffer.
  86 */
  87struct trace_buffer *
  88__ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
  89
  90/*
  91 * Because the ring buffer is generic, if other users of the ring buffer get
  92 * traced by ftrace, it can produce lockdep warnings. We need to keep each
  93 * ring buffer's lock class separate.
  94 */
  95#define ring_buffer_alloc(size, flags)                  \
  96({                                                      \
  97        static struct lock_class_key __key;             \
  98        __ring_buffer_alloc((size), (flags), &__key);   \
  99})
 100
 101int ring_buffer_wait(struct trace_buffer *buffer, int cpu, int full);
 102__poll_t ring_buffer_poll_wait(struct trace_buffer *buffer, int cpu,
 103                          struct file *filp, poll_table *poll_table);
 104
 105
 106#define RING_BUFFER_ALL_CPUS -1
 107
 108void ring_buffer_free(struct trace_buffer *buffer);
 109
 110int ring_buffer_resize(struct trace_buffer *buffer, unsigned long size, int cpu);
 111
 112void ring_buffer_change_overwrite(struct trace_buffer *buffer, int val);
 113
 114struct ring_buffer_event *ring_buffer_lock_reserve(struct trace_buffer *buffer,
 115                                                   unsigned long length);
 116int ring_buffer_unlock_commit(struct trace_buffer *buffer,
 117                              struct ring_buffer_event *event);
 118int ring_buffer_write(struct trace_buffer *buffer,
 119                      unsigned long length, void *data);
 120
 121void ring_buffer_nest_start(struct trace_buffer *buffer);
 122void ring_buffer_nest_end(struct trace_buffer *buffer);
 123
 124struct ring_buffer_event *
 125ring_buffer_peek(struct trace_buffer *buffer, int cpu, u64 *ts,
 126                 unsigned long *lost_events);
 127struct ring_buffer_event *
 128ring_buffer_consume(struct trace_buffer *buffer, int cpu, u64 *ts,
 129                    unsigned long *lost_events);
 130
 131struct ring_buffer_iter *
 132ring_buffer_read_prepare(struct trace_buffer *buffer, int cpu, gfp_t flags);
 133void ring_buffer_read_prepare_sync(void);
 134void ring_buffer_read_start(struct ring_buffer_iter *iter);
 135void ring_buffer_read_finish(struct ring_buffer_iter *iter);
 136
 137struct ring_buffer_event *
 138ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
 139void ring_buffer_iter_advance(struct ring_buffer_iter *iter);
 140void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
 141int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
 142bool ring_buffer_iter_dropped(struct ring_buffer_iter *iter);
 143
 144unsigned long ring_buffer_size(struct trace_buffer *buffer, int cpu);
 145
 146void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu);
 147void ring_buffer_reset_online_cpus(struct trace_buffer *buffer);
 148void ring_buffer_reset(struct trace_buffer *buffer);
 149
 150#ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
 151int ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
 152                         struct trace_buffer *buffer_b, int cpu);
 153#else
 154static inline int
 155ring_buffer_swap_cpu(struct trace_buffer *buffer_a,
 156                     struct trace_buffer *buffer_b, int cpu)
 157{
 158        return -ENODEV;
 159}
 160#endif
 161
 162bool ring_buffer_empty(struct trace_buffer *buffer);
 163bool ring_buffer_empty_cpu(struct trace_buffer *buffer, int cpu);
 164
 165void ring_buffer_record_disable(struct trace_buffer *buffer);
 166void ring_buffer_record_enable(struct trace_buffer *buffer);
 167void ring_buffer_record_off(struct trace_buffer *buffer);
 168void ring_buffer_record_on(struct trace_buffer *buffer);
 169bool ring_buffer_record_is_on(struct trace_buffer *buffer);
 170bool ring_buffer_record_is_set_on(struct trace_buffer *buffer);
 171void ring_buffer_record_disable_cpu(struct trace_buffer *buffer, int cpu);
 172void ring_buffer_record_enable_cpu(struct trace_buffer *buffer, int cpu);
 173
 174u64 ring_buffer_oldest_event_ts(struct trace_buffer *buffer, int cpu);
 175unsigned long ring_buffer_bytes_cpu(struct trace_buffer *buffer, int cpu);
 176unsigned long ring_buffer_entries(struct trace_buffer *buffer);
 177unsigned long ring_buffer_overruns(struct trace_buffer *buffer);
 178unsigned long ring_buffer_entries_cpu(struct trace_buffer *buffer, int cpu);
 179unsigned long ring_buffer_overrun_cpu(struct trace_buffer *buffer, int cpu);
 180unsigned long ring_buffer_commit_overrun_cpu(struct trace_buffer *buffer, int cpu);
 181unsigned long ring_buffer_dropped_events_cpu(struct trace_buffer *buffer, int cpu);
 182unsigned long ring_buffer_read_events_cpu(struct trace_buffer *buffer, int cpu);
 183
 184u64 ring_buffer_time_stamp(struct trace_buffer *buffer);
 185void ring_buffer_normalize_time_stamp(struct trace_buffer *buffer,
 186                                      int cpu, u64 *ts);
 187void ring_buffer_set_clock(struct trace_buffer *buffer,
 188                           u64 (*clock)(void));
 189void ring_buffer_set_time_stamp_abs(struct trace_buffer *buffer, bool abs);
 190bool ring_buffer_time_stamp_abs(struct trace_buffer *buffer);
 191
 192size_t ring_buffer_nr_pages(struct trace_buffer *buffer, int cpu);
 193size_t ring_buffer_nr_dirty_pages(struct trace_buffer *buffer, int cpu);
 194
 195void *ring_buffer_alloc_read_page(struct trace_buffer *buffer, int cpu);
 196void ring_buffer_free_read_page(struct trace_buffer *buffer, int cpu, void *data);
 197int ring_buffer_read_page(struct trace_buffer *buffer, void **data_page,
 198                          size_t len, int cpu, int full);
 199
 200struct trace_seq;
 201
 202int ring_buffer_print_entry_header(struct trace_seq *s);
 203int ring_buffer_print_page_header(struct trace_seq *s);
 204
 205enum ring_buffer_flags {
 206        RB_FL_OVERWRITE         = 1 << 0,
 207};
 208
 209#ifdef CONFIG_RING_BUFFER
 210int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
 211#else
 212#define trace_rb_cpu_prepare    NULL
 213#endif
 214
 215#endif /* _LINUX_RING_BUFFER_H */
 216