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 ring_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 ring_buffer_event *event);
  65
  66/*
  67 * ring_buffer_discard_commit will remove an event that has not
  68 *   been committed yet. If this is used, then ring_buffer_unlock_commit
  69 *   must not be called on the discarded event. This function
  70 *   will try to remove the event from the ring buffer completely
  71 *   if another event has not been written after it.
  72 *
  73 * Example use:
  74 *
  75 *  if (some_condition)
  76 *    ring_buffer_discard_commit(buffer, event);
  77 *  else
  78 *    ring_buffer_unlock_commit(buffer, event);
  79 */
  80void ring_buffer_discard_commit(struct ring_buffer *buffer,
  81                                struct ring_buffer_event *event);
  82
  83/*
  84 * size is in bytes for each per CPU buffer.
  85 */
  86struct ring_buffer *
  87__ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
  88
  89/*
  90 * Because the ring buffer is generic, if other users of the ring buffer get
  91 * traced by ftrace, it can produce lockdep warnings. We need to keep each
  92 * ring buffer's lock class separate.
  93 */
  94#define ring_buffer_alloc(size, flags)                  \
  95({                                                      \
  96        static struct lock_class_key __key;             \
  97        __ring_buffer_alloc((size), (flags), &__key);   \
  98})
  99
 100int ring_buffer_wait(struct ring_buffer *buffer, int cpu, int full);
 101__poll_t ring_buffer_poll_wait(struct ring_buffer *buffer, int cpu,
 102                          struct file *filp, poll_table *poll_table);
 103
 104
 105#define RING_BUFFER_ALL_CPUS -1
 106
 107void ring_buffer_free(struct ring_buffer *buffer);
 108
 109int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size, int cpu);
 110
 111void ring_buffer_change_overwrite(struct ring_buffer *buffer, int val);
 112
 113struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer,
 114                                                   unsigned long length);
 115int ring_buffer_unlock_commit(struct ring_buffer *buffer,
 116                              struct ring_buffer_event *event);
 117int ring_buffer_write(struct ring_buffer *buffer,
 118                      unsigned long length, void *data);
 119
 120void ring_buffer_nest_start(struct ring_buffer *buffer);
 121void ring_buffer_nest_end(struct ring_buffer *buffer);
 122
 123struct ring_buffer_event *
 124ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts,
 125                 unsigned long *lost_events);
 126struct ring_buffer_event *
 127ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts,
 128                    unsigned long *lost_events);
 129
 130struct ring_buffer_iter *
 131ring_buffer_read_prepare(struct ring_buffer *buffer, int cpu, gfp_t flags);
 132void ring_buffer_read_prepare_sync(void);
 133void ring_buffer_read_start(struct ring_buffer_iter *iter);
 134void ring_buffer_read_finish(struct ring_buffer_iter *iter);
 135
 136struct ring_buffer_event *
 137ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
 138struct ring_buffer_event *
 139ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
 140void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
 141int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
 142
 143unsigned long ring_buffer_size(struct ring_buffer *buffer, int cpu);
 144
 145void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
 146void ring_buffer_reset(struct ring_buffer *buffer);
 147
 148#ifdef CONFIG_RING_BUFFER_ALLOW_SWAP
 149int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 150                         struct ring_buffer *buffer_b, int cpu);
 151#else
 152static inline int
 153ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 154                     struct ring_buffer *buffer_b, int cpu)
 155{
 156        return -ENODEV;
 157}
 158#endif
 159
 160bool ring_buffer_empty(struct ring_buffer *buffer);
 161bool ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);
 162
 163void ring_buffer_record_disable(struct ring_buffer *buffer);
 164void ring_buffer_record_enable(struct ring_buffer *buffer);
 165void ring_buffer_record_off(struct ring_buffer *buffer);
 166void ring_buffer_record_on(struct ring_buffer *buffer);
 167bool ring_buffer_record_is_on(struct ring_buffer *buffer);
 168bool ring_buffer_record_is_set_on(struct ring_buffer *buffer);
 169void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
 170void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);
 171
 172u64 ring_buffer_oldest_event_ts(struct ring_buffer *buffer, int cpu);
 173unsigned long ring_buffer_bytes_cpu(struct ring_buffer *buffer, int cpu);
 174unsigned long ring_buffer_entries(struct ring_buffer *buffer);
 175unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
 176unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
 177unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
 178unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);
 179unsigned long ring_buffer_dropped_events_cpu(struct ring_buffer *buffer, int cpu);
 180unsigned long ring_buffer_read_events_cpu(struct ring_buffer *buffer, int cpu);
 181
 182u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
 183void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
 184                                      int cpu, u64 *ts);
 185void ring_buffer_set_clock(struct ring_buffer *buffer,
 186                           u64 (*clock)(void));
 187void ring_buffer_set_time_stamp_abs(struct ring_buffer *buffer, bool abs);
 188bool ring_buffer_time_stamp_abs(struct ring_buffer *buffer);
 189
 190size_t ring_buffer_nr_pages(struct ring_buffer *buffer, int cpu);
 191size_t ring_buffer_nr_dirty_pages(struct ring_buffer *buffer, int cpu);
 192
 193void *ring_buffer_alloc_read_page(struct ring_buffer *buffer, int cpu);
 194void ring_buffer_free_read_page(struct ring_buffer *buffer, int cpu, void *data);
 195int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
 196                          size_t len, int cpu, int full);
 197
 198struct trace_seq;
 199
 200int ring_buffer_print_entry_header(struct trace_seq *s);
 201int ring_buffer_print_page_header(struct trace_seq *s);
 202
 203enum ring_buffer_flags {
 204        RB_FL_OVERWRITE         = 1 << 0,
 205};
 206
 207#ifdef CONFIG_RING_BUFFER
 208int trace_rb_cpu_prepare(unsigned int cpu, struct hlist_node *node);
 209#else
 210#define trace_rb_cpu_prepare    NULL
 211#endif
 212
 213#endif /* _LINUX_RING_BUFFER_H */
 214